add doc about newcodegen

release 12.3
fix invalid const-folding of certain strings char classification routines such as isupper()
2026-10-22 20:02:27 +00:00 · 2026-08-05 03:45:14 +02:00 · 2026-08-05 03:25:32 +02:00 · 2026-08-05 02:55:36 +02:00 · 2026-08-05 02:54:59 +02:00 · 2026-08-05 02:51:37 +02:00
507 changed files with 58728 additions and 23268 deletions
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+---
+description: Startup workflow to load project context
+---
+
+1. Read the file `AGENTS.md` in the project root as initial system prompt to build context and instructions about the project structure, module descriptions, and development commands.
@@ -0,0 +1,291 @@
+---
+name: asm6502-coder
+description: Writing or understanding 6502/65C02 assembly code using 64tass syntax, for use as stand alone .asm or inline within Prog8 programs
+---
+
+# 65(C)02 Assembly Coder Skill
+
+You are an expert MOS 6502 assembly development assistant. Keep responses concise and practical — prefer short, correct code examples over lengthy prose.
+You are working with **6502/65C02 assembly** using **64tass syntax**, in separate `*.asm` files or embedded in a Prog8 program (inside `%asm {{ }}` blocks or `asmsub` routines). Follow all rules below.
+
+## Assembler: 64tass Syntax
+### Formatting Rules
+- Labels start in the first column of the line.
+- Instructions are indented at least 4 spaces.
+- Two spaces between the instruction opcode and its operand (e.g., `lda  #1`, `sta  $d020`).
+- End-of-line comments are preceded by two spaces before the `;` (e.g., `sta  $d020  ; border color`).
+- If a comment is the only thing on a line, it starts in the first column (no indentation).
+- Opcodes and operands are written in lowercase (e.g., `lda`, not `LDA`; `$d020`, not `$D020`).
+
+- **NOT ca65/cc65** or other assemblers. Key differences:
+- `.proc` / `.pend` for procedures (scoping)
+- `_label` for local labels (prefixed with underscore, scoped to `.proc`)
+- **Symbol aliases**: inside a `.proc`, use `_name = P8ZP_SCRATCH_B1` to give a scratch variable a descriptive name.
+- **Anonymous labels**: defined as `+` (forward) or `-` (backward) at the start of a line.
+  - **CRITICAL DISTINCTION**: Label **definitions** are always just a single `+` or `-`. Label **references** use `+`, `++`, `+++` to refer to the 1st, 2nd, 3rd upcoming forward label, and `-`, `--`, `---` for the 1st, 2nd, 3rd preceding backward label.
+  - `+` refers to the NEXT upcoming `+` label, `++` refers to the ONE AFTER that, etc.
+  - `-` refers to the MOST RECENT `-` label, `--` to the one before that, etc.
+  - When a `+` label is passed, the forward-reference count resets (so `++` then refers to the next one after that new label)
+  - Example:
+    ```asm
+    -   dex         ; backward label '-'
+        bne -       ; branch to most recent '-' (the dex above)
+        ldx #5
+    +   dex         ; forward label '+'
+        bne +       ; branch to this same '+' (forward)
+        sta $400
+    +   lda #0      ; second '+' label definition (just '+')
+        bne ++      ; branch to the '++' below (third forward '+')
+        rts
+    +   inc $d020   ; third forward label definition (just '+', referred to as '++')
+    ```
+- Data directives: `.byte`, `.word`, `.dword`, `.fill` (allocate space)
+- Equates: `label = value` (not `label .equ value` or `#define`)
+- **Number Literals**: Hex `$1234`, Binary `%10101010`, Decimal `123`.
+- Zero-page variables defined with `=`
+- `.text` for inline string data
+- **Conditional assembly**: `.if`, `.elsif`, `.else`, `.endif`
+- **Memory Sections**: `.section <name>`, `.send <name>` (common sections: `CODE`, `DATA`, `BSS`, `BSS_NOCLEAR`)
+
+## Instructions
+- **Instructions like `rol`, `ror`, `asl`, `lsr` (and `inc`, `dec` on 65C02) require an explicit operand for accumulator**: write `rol a`, `inc a`, etc., not just `rol` or `inc`.
+- Standard 6502 addressing modes: implied, immediate (`#`), zero-page (`zp`), zero-page,X (`zp,x`), absolute (`abs`), absolute,X (`abs,x`), absolute,Y (`abs,y`), indirect (`(abs)`), indirect,X (`(zp,x)`), indirect,Y (`(zp),y`), relative (branches), accumulator
+- Branches: `bne`, `beq`, `bmi`, `bpl`, `bcs`, `bcc`, `bvs`, `bvc` (relative, max +127/-128 bytes)
+- Jumps: `jmp` (absolute or indirect), `jsr`/`rts` (subroutine call/return)
+- No `push`/`pop` mnemonics — use `pha`/`pla` (byte) and `txa`/`phx`/`plx`/`tay`/`phy`/`ply` for registers
+
+### Instruction Side Effects (Flags)
+- **`Z` (Zero)**: Set if the result of an operation is 0.
+- **`N` (Negative)**: Set if bit 7 of the result is 1.
+- **`C` (Carry)**: Used for unsigned overflow and shifts. `cmp` sets `C` if `Register >= Operand`.
+- **`V` (Overflow)**: Set if a signed arithmetic operation overflowed.
+- **Commonly affected by**: `lda`, `ldx`, `ldy`, `inx`, `dex`, `tax`, `tay`, `txa`, `tya`, `and`, `ora`, `eor`, `asl`, `lsr`, `rol`, `ror`, `adc`, `sbc`, `cmp`, `cpx`, `cpy`, `bit`.
+- **Note**: `lda`, `ldx`, `ldy` do NOT affect the Carry flag. Only `adc`, `sbc`, `cmp`, and shift/rotate instructions affect Carry.
+
+## 6502 vs 65C02
+- **CX16 target only**: can use WDC 65C02 instructions — `stz`, `phx`, `plx`, `phy`, `ply`, `bra`, `trb`, `tsb`, `stp`, `wai`, `inc a`, `dec a`, `bit #imm`, `bit zp,x`, `bit abs,x`, `jmp (abs,x)`, and `(zp)` indirect addressing mode (e.g., `lda (zp)`).
+- **C64, C128, PET32 targets**: original 6502 only — no `stz`, no `phx`/`plx`/`phy`/`ply`, no `bra` etc.
+- **Note**: The Rockwell/bit-manipulation instructions (`rmb`, `smb`, `bbr`, `bbs`) are **NOT** available.
+- Check the target before using 65C02-specific instructions
+- **6502 / 65C02 instruction reference table**: https://www.pagetable.com/c64ref/6502/?cpu=65c02&tab=4 (provides exact instruction details for all opcodes: operation, addressing modes, byte length, and cycle count).
+
+## Commander X16 Memory Map
+```
+Bank    Offset      Content
+        $0000-$9EFF Fixed/System RAM
+        $9F00-$9FFF I/O Area (VIA, VERA, YM2151)
+$00-$FF:$A000-$BFFF Banked RAM (max 2 MiB, often 512 KiB) (256x8K banks)
+$00-$1F:$C000-$FFFF System ROM (512 KiB) (32x16K banks)
+```
+- Bank registers (in zeropage): `$00` selects the current RAM bank (0-255), `$01` selects the current ROM bank (0-31). For JSRFAR/banked calls from Prog8, use `extsub @bank ...` instead of manipulating these directly.
+- Full hardware specs at https://ayce.dev/emptyx16.html#emptyx16---x16-hardware-specs
+
+## Calling Convention / Register Conventions
+- **Accumulator (A)**: 8-bit, used for most arithmetic, data movement, return values
+- **X register**: 8-bit, often used for indexing, loop counters
+- **Y register**: 8-bit, often used for indirect addressing index
+- **Processor Status (P)**: flags — carry (C), zero (Z), negative/N (sign bit 7), overflow (V), decimal (D), interrupt (I), break (B)
+- **No caller-saved vs callee-saved convention** — list all modified registers in `clobbers (A, X, Y)` when writing `asmsub`
+- The CPU stack (SP, $0100-$01FF) is limited (usually ~128 bytes free). Do not overflow it
+
+## Assembly within Prog8 Programs
+
+### `%asm {{ }}` blocks
+- Embed arbitrary 64tass assembly directly in your Prog8 source
+- Access Prog8 symbols using their prefixed names (see below)
+- Can be placed inside subroutines or at block level
+
+### `asmsub` (assembly subroutine)
+- For kernel (ROM) routines or low-level assembly
+- Parameters passed via registers: `@A`, `@X`, `@Y`, `@AX` (A low, X high), `@AY` (A low, Y high), `@R0`-`@R15`, `@FAC1`/`@FAC2` (float), `@Pc` (carry), `@Pz` (zero)
+- Return value: `-> type @register` — also via `@Pz`/`@Pc` for flags
+- Clobbers: `clobbers (A, X, Y)` — MUST list all modified registers
+- **CRITICAL**: Parameter names in `asmsub` are **documentation only**. You MUST use the actual registers in your assembly code, NOT the parameter names (unless you create aliases yourself).
+- Create symbolic aliases at assembly top for clarity: `x1 = cx16.r0`, `y1 = cx16.r0L`
+- Accessing Prog8 parameters if they were NOT mapped to registers: use `p8v_paramname`. (Mapping to registers is preferred for speed).
+
+Example:
+```prog8
+asmsub line(uword x1 @R0, ubyte y1 @A, uword x2 @R1, ubyte y2 @Y) clobbers (A, X, Y) {
+    %asm {{
+        x1 = cx16.r0
+        x2 = cx16.r1
+        lda  x1        ; use alias, not "_x1"
+    }}
+}
+```
+
+### `asmsub` parameter annotation reference
+| Annotation | Register | Size |
+|------------|----------|------|
+| `@A` | Accumulator | 8-bit |
+| `@X` | X register | 8-bit |
+| `@Y` | Y register | 8-bit |
+| `@AX` | A (low) + X (high) | 16-bit |
+| `@AY` | A (low) + Y (high) | 16-bit |
+| `@R0`-`@R15` | cx16 virtual registers | 16-bit each |
+| `@FAC1`/`@FAC2` | Floating-point accumulators | 5-byte float |
+| `@Pc` | Carry flag | bool |
+| `@Pz` | Zero flag | bool |
+
+## Accessing Prog8 Symbols from Assembly
+All Prog8 symbols are prefixed when accessed from assembly:
+
+| Prefix | Refers to | Example |
+|--------|-----------|---------|
+| `p8v_` | Variables, parameters | `p8v_myvar` |
+| `p8s_` | Subroutines | `p8s_mysub` |
+| `p8b_` | Blocks | `p8b_myblock` |
+| `p8c_` | Constants, enum members | `p8c_myconst`, `p8c_MyEnum_Member` |
+| `p8l_` | Labels | `p8l_mylabel` |
+| `p8t_` | Struct types | `p8t_MyStruct` |
+| `p8_` | Other symbols | |
+
+- **Fully qualified**: e.g., `p8b_myblock.p8v_myvar`, `p8b_myblock.p8s_mysub.p8v_localvar`
+- Within a `.proc` (subroutine) in your assembly, short names often work (assembler scoping)
+- **`%option no_symbol_prefixing`**: disables all prefixes. Stdlib modules (`cbm`, `cx16`, `txt`) use this — you can write `cbm.CHROUT` directly
+- **Split word arrays**: two separate byte arrays — append `_lsb` and `_msb` to the name: `p8v_myarray_lsb`, `p8v_myarray_msb`
+
+## Zeropage Usage
+- Do NOT use arbitrary zeropage locations. Only use these predefined scratch variables:
+  - `P8ZP_SCRATCH_B1` (byte)
+  - `P8ZP_SCRATCH_REG` (byte)
+  - `P8ZP_SCRATCH_W1` (word)
+  - `P8ZP_SCRATCH_W2` (word)
+  - `P8ZP_SCRATCH_PTR` (word)
+- On CX16: virtual registers `cx16.r0`-`cx16.r15` are in zeropage (and their low/high bytes: `cx16.r0L`, `cx16.r0H`, etc.)
+- Virtual registers `cx16.r0`-`cx16.r15` are available on ALL targets, but only on CX16 in zeropage
+- Assume the scratch variables are not consecutive in zeropage. The CX16 virtual registers ARE consecutive in memory though.
+- For additional temporary storage, allocate regular variables in BSS
+- **CRITICAL: NEVER use hardcoded zeropage addresses** (like `$1e`, `$22`, `$7c`, etc.) to reference P8ZP_SCRATCH registers or cx16 virtual registers. Their addresses differ per compilation target. **ALWAYS** use the symbolic names (`P8ZP_SCRATCH_W1`, `cx16.r14`, `cx16.r14+1`, etc.) so the assembler resolves the correct address for the target.
+
+## Common 6502 Patterns
+
+### Common Branch Logic (Comparisons)
+| Logic | Unsigned | Signed |
+|-------|----------|--------|
+| `A == imm` | `cmp #imm`, `beq label` | (Same) |
+| `A != imm` | `cmp #imm`, `bne label` | (Same) |
+| `A < imm` | `cmp #imm`, `bcc label` | `sec`, `sbc #imm`, `bvc *+4`, `eor #$80`, `bmi label` |
+| `A >= imm` | `cmp #imm`, `bcs label` | `sec`, `sbc #imm`, `bvc *+4`, `eor #$80`, `bpl label` |
+| `A <= imm` | `beq label`, `bcc label` | (Use complex signed logic or reorder) |
+| `A > imm` | `beq +`, `bcs label`, `+` | (Use complex signed logic or reorder) |
+
+### Looping (downto with BNE)
+```asm
+        ldx #count
+loop    ; do work here
+        dex
+        bne loop        ; loop while X != 0 (runs 'count' times)
+```
+
+### Self-Modifying Code (SMC) — Avoid When Possible
+**Do NOT use self-modifying code unless absolutely necessary** — self-modifying code writes to the code segment at runtime, which means it **cannot run from ROM** and is generally fragile, hard to debug, and violates the expected behavior of modern tooling (emulators, debuggers, etc.). Prefer lookup tables, indirect jumps via a vector in RAM, or alternative algorithms that keep code in place.
+
+### Self-Modifying Code (SMC) Detection
+Look for `sta`, `stx`, or `sty` pointing into code labels:
+```asm
+        lda #$42
+        sta _target+1   ; Modifies the immediate operand of the LDA at _target
+        ...
+_target lda #$00        ; This #$00 will be replaced by #$42 at runtime
+```
+
+### Indirect indexed read (table of data)
+```asm
+        ldy #index
+        lda (ptr),y     ; read byte at address stored in zp ptr + Y
+```
+
+### 16-bit arithmetic (word add)
+```asm
+        clc
+        lda word1_lo
+        adc word2_lo
+        sta result_lo
+        lda word1_hi
+        adc word2_hi
+        sta result_hi
+```
+
+### Calling a Prog8 subroutine from assembly
+```asm
+        jsr p8s_myblock.p8s_mysub
+```
+
+### Reading a word variable
+```asm
+        lda p8v_myword          ; loads LSB
+        ldy p8v_myword+1        ; loads MSB (word variables are stored LSB-first)
+```
+
+## CPU Quirks and Pitfalls
+
+### JMP ($xxFF) Page Wrap Bug (NMOS 6502)
+- **Problem**: On original 6502 CPUs, `jmp ($caff)` will fetch the LSB from `$caff` but the MSB from `$ca00` (instead of `$cb00`).
+- **Target**: Affects C64, C128, PET32.
+- **Solution**: Avoid placing indirect jump vectors on a page boundary, or use the CX16 (65C02) which fixed this bug.
+
+### BRK Instruction and the "Signature Byte"
+- **Behavior**: After a `BRK` instruction, the return address on the stack is incremented by **2**. This means the CPU skips the byte immediately following the `BRK` opcode.
+- **Usage**: This skipped byte is often used as a "signature" or parameter byte for the BRK handler.
+
+### BIT Instruction Flags
+- **Absolute/Zero-page**: `bit $1234` copies bit 7 of the memory value to the **N** flag and bit 6 to the **V** flag. The **Z** flag is set based on `A AND memory`.
+- **Immediate (65C02 only)**: `bit #$01` only affects the **Z** flag; it does **NOT** modify N or V.
+- **NMOS 6502**: Does **not** support `bit #imm`.
+
+### The "B" (Break) Flag
+- **Quirk**: The B flag (bit 4 of the status register) doesn't actually exist in the hardware status register. It only exists on the stack after a `PHP` or `BRK` instruction (set to 1) or a hardware IRQ/NMI (set to 0).
+- **Detection**: To tell if an interrupt was caused by `BRK` or a hardware IRQ, your handler must `pla`, `and #$10`, and check the result.
+
+### Decimal Mode Flag (D) Persistence
+- **Pitfall**: On NMOS 6502, the `D` flag is **not** cleared on interrupt. Always use `cld` in IRQ handlers. On 65C02, it is cleared automatically, but `cld` is still good practice.
+- **ADC/SBC**: Be extremely careful with arithmetic if you haven't explicitly set or cleared the `D` flag, as its state might be unknown.
+
+## Optimization Tips
+- **`stz` (65C02 only)**: Saves cycles and bytes compared to `lda #0`, `sta ...`.
+- **`bra` (65C02 only)**: Shorter and usually faster than `jmp`.
+- **Avoid `clc` before `bcc`**: `cmp` already sets the carry flag correctly for `bcc`/`bcs`.
+- **`inx` / `dex` vs `clc`+`adc #1`**: Incrementing/decrementing is faster and doesn't affect the carry flag.
+- **Zero-page usage**: Accessing variables in zeropage is 1 cycle faster and 1 byte shorter than absolute addressing.
+- **Cycle Counting**: Most instructions take 2-4 cycles. `jsr` takes 6, `rts` takes 6. Branches take 2 (no branch), 3 (branch taken), or 4 (branch taken across page boundary).
+
+## 64tass Macros
+Define macros for common tasks:
+```asm
+pushax  .macro
+        pha
+        txa
+        pha
+        .endm
+
+popax   .macro
+        pla
+        tax
+        pla
+        .endm
+```
+Call them with `#pushax` and `#popax`.
+
+## IRQ Handler Best Practices
+- **Clear the Decimal Flag (`cld`)**: On the original 6502, the decimal flag (`D`) is **not** automatically cleared when an interrupt occurs. If the interrupted code was in decimal mode, your handler will also run in decimal mode, causing arithmetic errors. Always call `cld` at the beginning of your handler. The 65C02 clears it automatically, but `cld` is still recommended for portability.
+
+## Invoking the Assembler (64tass)
+If you need to manually invoke `64tass` to assemble a generated `.asm` file, you should be aware of the default arguments that `prog8c` supplies to ensure compatibility with the generated code:
+
+- `--ascii`: **CRITICAL.** Prog8 generates character and string data in ASCII. Without this flag, `64tass` defaults to PETSCII, which will garble your strings.
+- `--case-sensitive`: Prog8 is case-sensitive and expects the assembler to be as well.
+- `--long-branch`: Enables automatic conversion of relative branches (`beq`, `bne`, etc.) to absolute jumps if the target is out of range. Prog8 relies on this.
+- `-Wno-implied-reg`: Suppresses warnings when the accumulator `a` is omitted from instructions like `rol`, `lsr`, etc. (though the skill recommends always using `rol a` for clarity).
+- `-Wall`: Enables all warnings.
+- `--cbm-prg` (or `--atari-xex` / `--nostart`): Sets the output format and adds the appropriate load address header.
+
+### Optional but Recommended for Debugging:
+- `--vice-labels --labels=labels.txt`: Generates a label file that can be loaded into the VICE monitor (`load_labels "labels.txt"`) to see your Prog8 symbol names while debugging.
+- `--list=listing.txt`: Generates a full assembly listing file with addresses and opcodes.
+
+### Example manual invocation:
+```bash
+64tass --ascii --case-sensitive --long-branch -Wall --cbm-prg -o myprogram.prg myprogram.asm
+```
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+---
+name: prog8-coder
+description: Writing or understanding Prog8 programs
+---
+
+# Prog8 Coder Skill
+
+You are an expert retro system development assistant, versed in the Prog8 programming language. Keep responses concise and practical — prefer short, correct code examples over lengthy prose.
+You are working with **Prog8** source code (`.p8` files) or its Intermediate Representation (`.p8ir` files). Prog8 targets 8-bit systems (C64, CX16, C128, PET32) with the 6502 CPU, plus a `virtual` target for testing.
+Follow ALL the rules below carefully.
+
+## General & Setup
+- A program = a `main` block containing a `start` subroutine entry point, plus optional other subroutines/blocks
+- Add `%zeropage basicsafe` at the top of your program to allow clean return on exit (instead of resetting the machine/emulator)
+- Module imports: `%import modulename` — no `as` aliasing. Use the module's defined prefix (e.g., `%import textio` → `txt.xxx`)
+- `.p8ir` files are the **Intermediate Representation** — target-independent, executable via `prog8c -vm file.p8ir`
+- **Library search**: `prog8c -libsearch <regex>` to find routines in the embedded stdlib (e.g., `prog8c -libsearch "txt\."`)
+- **Library dump**: `prog8c -libdump <dir>` to extract all embedded library source files
+- **`sys` module**: always available, no import needed
+- **CX16 programs**: add `%encoding iso`, call `txt.iso()` in `start()`, end with `sys.poweroff_system()`
+
+## Datatypes & Variables
+- Primitives: `bool`, `byte`, `ubyte`, `word`, `uword`, `long`, `float`, `str`
+- `ubyte`/`uword` = unsigned; `long` = signed 4-byte; `float` = 5-byte MS format; `str` = 0-terminated ubytes (max 255 chars)
+- **float requires `%import floats`** at top of file, else compiler errors
+- Arrays: max 256 bytes (512 for split word arrays). For larger data, use `memory()` + pointers
+- `memory(name, size)` returns a `uword` address to a statically reserved block of memory
+- To point a typed pointer at a `memory()` block, assign the uword directly: `^^MyStruct ptr = memory("name", size)`. The `^^Type:expression` syntax (below) only works with array literals, not general uword expressions.
+- Struct initialization: `^^StructType ptr = ^^StructType:[val1,val2,...]` (the `^^StructType:` can be omitted if inferable). This `^^Type:[...]` syntax does NOT work with variables or `memory()` — only literal arrays.
+- Struct definitions must be inside a block, not at file level.
+- Struct fields: simple types, `str`, and fixed-size arrays. Array fields: `ubyte[108] name`. `str` in struct = `^^ubyte`
+- Word/pointer arrays split into LSB/MSB by default. Override with `@nosplit`
+- **No call stack**: all variables statically allocated. No recursion without manual stack management
+- Variables zero-initialized (globals at start, locals on subroutine entry)
+- `@shared`, `@zp`, `@requirezp`, `@dirty`, `@nosplit` are **tags** that go on variable declarations. **Place them after the datatype (and array specifiers), before the variable name(s):**
+  ```
+  private ubyte[8] @shared vera_storage     ; single var with tag
+  ubyte @zp @shared varname                 ; multiple tags allowed
+  ubyte @requirezp var1                     ; require zeropage
+  ubyte[] @shared names                     ; array with tag
+  ```
+  The grammar is: `[private] datatype [arraydims] [tags...] identifierlist`
+- `@shared` marks variables as "used by external code" (assembly), prevents the optimizer from removing them
+- `@zp`/`@requirezp`: use sparingly — only for pointers (limited zeropage space)
+- Pointer-like typed pointers (`^^type`) support C-style scaled arithmetic; `uword` pointers always treat element as 1 byte
+- `&` = untyped address (uword); `&&` = typed pointer
+- Available zeropage scratch: `P8ZP_SCRATCH_B1`, `P8ZP_SCRATCH_REG`, `P8ZP_SCRATCH_W1`, `P8ZP_SCRATCH_W2`, `P8ZP_SCRATCH_PTR` — and cx16 virtual registers R0-R15 on all targets
+- Virtual registers (`cx16.r0`–`cx16.r15`): global 16-bit, NOT preserved across calls.
+- **WARNING: Virtual registers in ISR/IRQ handlers**: The virtual registers R0-R15 are *not preserved* across the IRQ handler call. If your handler uses them, it will corrupt the interrupted program's state. Either avoid using them in the handler, or save/restore with `cx16.save_virtual_registers()` / `cx16.restore_virtual_registers()`. This applies to all targets, not just CX16.
+- **WARNING: Long operations clobber R12-R15**: Some operations on `long` values use R12-R15 as temporary storage and will silently overwrite them. Do not rely on R12-R15 values when working with longs, and avoid using R12-R15 explicitly if your code uses long arithmetic.
+- **WARNING: VERA registers in ISR handlers (CX16)**: If your IRQ handler reads or writes VERA control registers (e.g., `cx16.VERA_DATA0`, `cx16.VERA_ADDR_L`, etc.), you must save and restore the VERA context around the handler's work using `cx16.save_vera_context()` / `cx16.restore_vera_context()`. Without this, the handler will corrupt any VERA operations (tilemap updates, sprite positioning, etc.) happening in the interrupted main program.
+- **IRQ handler best practices**: Keep handlers extremely short and fast — they run with interrupts disabled and steal cycles from the main program. Do NOT do lengthy processing, I/O, or complex subroutine calls inside the handler. Instead, set a boolean flag or semaphore that the main loop checks periodically, and do the actual work there.
+- Math performance: integer trig (`math.sin8`, `math.cos8`) uses fast LUTs; float trig (`floats.sin`/`cos`) is much slower
+
+## Recursion & Stack Management
+No call stack for variable storage — recursion overwrites locals. To handle it:
+1. **CPU hardware stack**: `push()`/`pushw()`/`pushl()`/`pushf()` and `pop()`/`popw()`/`popl()`/`popf()`. Save/restore locals around recursive calls
+2. **Software stacks**: `buffers.stack` (uword) / `buffers.smallstack` (ubyte). Both provide `push_b()`/`push_w()` and `pop_b()`/`pop_w()`
+3. **Iterative rewrite (preferred)**: Many recursive algorithms work as `repeat` loops with explicit bounds — avoids all stack overhead
+
+## Strings, Arrays & Pointers
+- `str` / array: max 256 bytes. `long[]` limited to 64 entries (64x4=256). `str[]` for string arrays: `str[5] names = ["a","b","c","d","e"]`
+- 2D arrays: `type[rows][cols] name`, access `name[r][c]`. Flat init list only (no nested `[[...]]`). Total size still ≤ 256 bytes
+- str/array passed as pointer to subroutine (receiving subroutine gets `^^ubyte` or `^^element`)
+- **No const pointers** or pointer-to-pointer currently supported
+- **Parsing limitation**: `pointer[index].field` as assignment target needs `^^`: `pointer[index]^^.field = value`
+- **Pre-allocate buffers**: `str buffer = "." * 50` (empty `""` allocates nothing — `strings.append()` will fail)
+- **No reassignment**: can't `buffer = "new text"` after declaration. Use `strings.copy()`/`strings.ncopy()`
+- String concat is expensive on 6502. Prefer separate prints over concatenation
+- **Efficient buffer iteration**: prefer `ptr++` + `@(ptr)` over `@(buffer + offset)`. Exception: if offset is a `ubyte` (≤ 255), `buffer[offset]` works fine
+- `@(ptr)` = peek/poke byte. For words: `peekw`/`pokew`, longs: `peekl`/`pokel`, floats: `peekf`/`pokef`, bools: `peekbool`/`pokebool`
+- Assigning a uword address to a `str` field of a struct is done by direct assignment. Compute the address in a uword variable first, then assign: `cx16.r0 = &namebufs + offset; entry.name = cx16.r0`. The `^^ubyte:(expr)` cast syntax does not parse — use a temp uword instead.
+- Use `len(array)` instead of hardcoded sizes
+- Array indexing is 0-based: `arr[0]` is first element
+- Static memory only — real dynamic allocation impossible, but can emulate with a simple arena allocator over a `memory()` slab
+
+## Logic & Control Flow
+- Logical operators (short-circuit, bool only): `and`, `or`, `xor`, `not`
+  - In `a and b`: if `a` is false, `b` is NOT evaluated
+  - In `a or b`: if `a` is true, `b` is NOT evaluated
+  - Important when `b` has side effects
+- Bitwise operators: `&`, `|`, `^`, `~`, `<<`, `>>`
+- Bit rotation: `rol()`/`ror()` (through carry), `rol2()`/`ror2()` (no carry)
+- CPU status flag branches: `if_cs`, `if_cc`, `if_z`, `if_nz` (compile to single 6502 branch instructions)
+- If-expressions for simple value assignments based on a choice
+- **Optional braces in if/else**: when the `if` or `else` body is a single statement, the `{ }` can be omitted. Place the statement on the next line, indented. Example:
+  ```
+  if x < 5
+      txt.print("small")
+  ```
+- `defer` defers statement execution until scope exit. Multiple defers fire in **reverse registration order** (LIFO / stack order — last deferred runs first). A defer is only registered if execution reaches that statement — conditional paths that skip the `defer` line will not register it.
+- `goto`, labels, jump lists allowed
+- **Common mistake**: `and`/`or` for bitmasking — use `&`/`|` instead!
+
+### The when Statement
+The `when` statement is a control flow construct that enables you to execute a specific action based on the value of an expression. It is generally more readable and often more efficient than a sequence of `if-else if` statements, as the compiler can optimize it into more efficient branching structures, such as a jump table.
+- **Expression**: Evaluates an expression and compares it against case values.
+- **Cases**: Defined by a value followed by the `->` operator.
+- **Blocks**: Use `{ }` to enclose multiple statements for a case.
+- **Else Clause**: Serves as a default handler; mandatory unless the expression type is fully covered.
+- **Efficiency**: Recommended for handling sets of fixed choices as it typically results in better assembly code.
+
+## Loop Constructs
+Prog8 supports these loop types. All support `break` and `continue` (except `unroll`).
+
+### `for` loop — iterate over a range or array
+- Loop variable **must be declared separately** before the `for` statement
+- Works with `ubyte`, `byte`, `uword`, `word`, `long`, pointer types (NOT `float`)
+- Iterates over ranges (`start to end`), descending ranges (`start downto end`), or arrays/strings
+- Optional `step <constant>` for non-unit step sizes
+- Loop variable value **after the loop is undefined** — don't rely on it
+- Descending loops with `downto` usually produce more efficient 6502 code
+```
+ubyte i
+for i in 20 to 155 {
+    ; body
+    break       ; exit loop
+    continue    ; next iteration
+}
+
+; descending
+for i in 155 downto 20 {}
+for i in 155 to 20 step -1 {}
+
+; iterate over array elements
+uword[] fib = [0, 1, 1, 2, 3, 5, 8, 13]
+uword num
+for num in fib {
+    ...
+}
+```
+
+### `while` loop — repeat while condition is true
+```
+while condition {
+    ; body
+    break
+    continue
+}
+```
+
+### `do`-`until` loop — always executes body at least once
+```
+do {
+    ; body
+    break
+    continue
+} until condition
+```
+
+### `repeat` loop — repeat a fixed number of times (most efficient)
+- Most efficient code generation — prefer over `for` when loop variable not needed
+- Omit count for infinite loop (still supports `break`)
+```
+repeat 15 {
+    ; body
+    break
+    continue
+}
+
+; infinite:
+repeat {
+    ; body
+    break if x==5
+}
+```
+
+### `unroll` loop — compile-time code duplication
+- Not a real loop — duplicates body N times at compile time
+- No `break`/`continue` allowed
+- Only simple statements (assignments, calls) in body
+- Constant iteration count required
+```
+unroll 80 {
+    cx16.VERA_DATA0 = 255
+}
+```
+
+## Subroutines & Return Values
+- **Don't use `private` on subroutines and variables** (including nested ones) unless the user asks for it. Everything is public by default in Prog8 — follow that convention.
+- `inline` keyword for subroutines to suggest inlining
+- No **function overloading** (except builtins) and no **polymorphism** in general. This means you must call specific routines for different types (e.g., `txt.print_ub(val)` vs `txt.print_w(val)` instead of a generic `print(val)`). Cannot use builtin names (msw, lsw, msb, lsb, mkword, mklong, peek, peekw, peekl, etc.) as variable/sub names
+- Can return 0, 1, or multiple values: `a, b, c = routine()`. Use `void` to skip: `void routine()`, `a, void, c = routine()`
+- Nested subroutines access parent scope variables directly
+
+## Assembly Subroutines (asmsub)
+For low-level assembly that gets arguments via registers and returns values in registers.
+- **Syntax**: `[private] [inline] asmsub subname(params) [clobbers(regs)] [-> returns] { %asm {{ ... }} }`
+- **Body Restriction**: The body of an `asmsub` **must only contain** a single `%asm {{ ... }}` node. Regular Prog8 statements or nested blocks are NOT allowed.
+- **Parameters**: `type name @register` (e.g., `ubyte val @A`, `uword addr @AX`, `float f @FAC1`).
+- **Return Values**: `-> type @register` (e.g., `-> ubyte @A`, `-> bool @Pz` for immediate branch use).
+- **Registers**:
+    - **8-bit**: `@A`, `@X`, `@Y`
+    - **16-bit**: `@AX`, `@AY`, `@XY` (register pairs)
+    - **Float**: `@FAC1`, `@FAC2` (Floating Point Accumulators)
+    - **Virtual**: `@R0`–`@R15` (16-bit), `@R0R1`–`@R14R15` (32-bit combined)
+    - **Status Flags (for returns)**: `@Pc` (Carry), `@Pz` (Zero), `@Pv` (Overflow), `@Pn` (Negative)
+- **Clobbers**: `clobbers (A, X, Y)` — list all hardware registers modified by the routine.
+- **Parameter names** are for documentation and type checking only. Use the registers in your assembly code.
+- **Inlining**: `inline asmsub` will paste the assembly code directly at the call site, avoiding `jsr`/`rts` overhead.
+
+## External Subroutines (extsub)
+Used to call routines at fixed memory addresses (like ROM KERNAL routines or third-party drivers).
+- **Syntax**: `[private] extsub [@bank <value>] address = subname(params) [clobbers(regs)] [-> returns]`
+- **Address**: Can be a hex literal (`$C000`) or a constant expression.
+- **Bank (optional)**: `@bank <integer>` (constant bank) or `@bank <identifier>` (variable bank).
+- **No Body**: Unlike `asmsub`, `extsub` has no `{ }` body; it just maps a signature to an address.
+- **Example**:
+  ```prog8
+  ; CX16 KERNAL CHROUT
+  extsub $FFD2 = chrout(ubyte char @A) clobbers(A, X, Y)
+
+  ; Routine in a specific RAM bank
+  extsub @bank 10 $C09F = audio_init() clobbers(A, X, Y) -> bool @Pc
+  ```
+
+## Inline Assembly
+When writing inline assembly (`%asm {{ }}` blocks or `asmsub` routines), load the **asm6502-coder** skill for formatting rules, symbol references, anonymous labels, and 64tass syntax details.
+
+
+
+## Standard Library
+- Find routines, functions, variables, modules and signatures in the symbol dump file for the given compilation target. 
+  - Online location: https://prog8.readthedocs.io/en/latest/libraries.html#low-fi-variable-and-subroutine-definitions-in-all-available-library-modules  they are linked there 1 for each compilation target
+  - Structure: builtin functions, then module sections with variables/constants (`type name`) and subroutines (`name (params) -> returntype`)
+- Text output: `textio` module (`txt.print`, `txt.chrout`, `txt.print_b`/`_ub`/`_w`/`_uw`/`_l`/`_bool`, `txt.print_f` for floats, `txt.spc()`, `txt.nl()`). **Note: Prog8 has no function overloading**, so you cannot use `txt.print(number)` — you must call the specific routine for the type (e.g., `txt.print_ub(val)` for an unsigned byte).
+- Math: `math` module — integer trig (`sin8`, `cos8`) via fast LUTs; `math.rnd()` for random numbers
+- String conversion: `conv` module (`str_uword`, `str2word`, etc.) — for printing numbers use txt routines instead
+- Char operations: `strings` module (`isdigit`, `isxdigit`, `isupper`, `islower`, `isletter`, `isspace`, `isprint`) — use these instead of manual ASCII/PETSCII arithmetic
+- String functions return useful lengths — capture them: `len = strings.copy(dest, src)`, `len = strings.append(buf, text)`, `len = strings.upper(mystr)`
+
+## Syntax & Formatting
+- Hex: `$FF` (not `0xFF`); Binary: `%1010` (not `0b1010`). Underscores for readability: `25_000_000`
+- 4-digit hex `$0000` = uword. No type suffixes (no `0L`). Cast: `expr as type`
+- Augmented assignment: `+=`, `-=`, `*=`, `/=`, `%=`, `&=`, `|=`, `^=`, `<<=`, `>>=`
+- **`;` starts a comment to end of line** — NOT a statement separator. One statement per line
+- **No `elif`**: use nested `else { if ... }`
+- Type casting: `expression as type` (e.g., `bytevar as word`). `as` has very low precedence (lower than arithmetic)
+- **No automatic type widening**: `byte*byte=byte` (overflow possible!). Cast explicitly
+- **No bare `{ }` blocks** like C/Java
+- Indentation: 4 spaces for .p8 and .asm files (no tabs)
+- Character encoding: 6502 targets use PETSCII by default (call `txt.lowercase()` at start for lowercase). Virtual target uses ISO (`%encoding iso` + `txt.iso()`)
+- Array size inferred from initializer: `str[] types = ["a", "b", "c"]`
+- Enums: `Enum::Value` syntax (double colon), declared inside a block. They are syntactic sugar for a list of `const` declarations, not a type. Use enums for related values, `const` for standalone
+- Avoid `globals.XXXX` — move constants closer to where they're used
+- Member access through pointers: use `.` for both direct and pointer access. The compiler infers the type. For complex assignment targets, `^^` may be needed: `ptr^^.field = value`
+- Qualified names: must use full path from top level (e.g., `cx16.r0`, not relative)
@@ -13,5 +13,7 @@ dist/
 build/
 out/
 output/
+gradle/
 .gradle/
 .kotlin/
+.git/
@@ -0,0 +1,45 @@
+# EditorConfig for Prog8 projects
+# Ensures consistent formatting across editors and team members
+# See https://editorconfig.org
+
+root = true
+
+# All files
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+# Prog8 source files (.p8)
+[*.p8]
+indent_style = space
+indent_size = 4
+
+# Assembly files (.asm) - 64tass syntax
+[*.asm]
+indent_style = space
+indent_size = 4
+
+# Kotlin compiler source files
+[*.kt]
+indent_style = space
+indent_size = 4
+trim_trailing_whitespace = false
+
+# Documentation files
+[*.md]
+trim_trailing_whitespace = false
+
+[*.rst]
+trim_trailing_whitespace = false
+
+# Gradle build files
+[*.gradle.kts]
+indent_style = space
+indent_size = 4
+
+# Git ignore files
+[.gitignore]
+indent_style = space
+indent_size = 2
@@ -10,32 +10,46 @@ jobs:

    steps:
      - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5

-      - name: build and install recent 64tass
+      - name: install 64tass
        run: |
-          sudo apt-get install -y make build-essential
-          git clone --depth=1 https://github.com/irmen/64tass
-          cd 64tass
-          make -j4
-          sudo make install          
+          sudo apt update
+          sudo apt install 64tass
+          64tass --version

      - name: Set up JDK 17
-        uses: actions/setup-java@v4
+        uses: actions/setup-java@v5
        with:
          java-version: 17
          distribution: temurin

-      - name: Build and test with Gradle
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v6
+
+      - name: Compile
+        run: ./gradlew compileKotlin compileTestKotlin --console=plain
+
+      - name: Test
+        run: ./gradlew test --continue --console=plain
+
+      - name: Package
        run: |
-          ./gradlew build shadowJar --no-daemon
+          ./gradlew shadowJar --console=plain
          sha256sum -b compiler/build/libs/*-all.jar > compiler/build/libs/hash.txt
-        
+
      - name: Create compiler shadowJar artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
        with:
          name: prog8-compiler-jar-zipped
          path: |
            compiler/build/libs/*-all.jar
            compiler/build/libs/hash.txt

+      - name: Upload test results
+        if: always()
+        uses: actions/upload-artifact@v6
+        with:
+          name: test-results
+          path: compiler/build/test-results/test/
+
@@ -3,6 +3,9 @@
 .idea/developer-tools.xml
 .idea/usage.statistics.xml
 .idea/shelf/
+.junie/
+.junie/memory/
+.serena
 build/
 dist/
 output/
@@ -14,6 +17,7 @@ out-old/
 *.prg
 *.bin
 *.p8ir
+*.bankedcalls
 *.labels.txt
 *.vm.txt
 *.vice-mon-list
@@ -22,6 +26,7 @@ parser/**/*.interp
 parser/**/*.tokens
 parser/**/*.java
 compiler/src/prog8/buildversion/*
+languageServer/src/prog8/buildversion/*
 *.py[cod]
 *.egg
 *.egg-info
@@ -35,7 +40,6 @@ parsetab.py
 .pytest_cache/
 .attach_pid*
 compiler/lib/
-
 .gradle
 sd*.img
 *.d64
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="JunieProjectTechnologies">
+    <option name="explicitlyEnabledTechs">
+      <set>
+        <option value="junie.python" />
+      </set>
+    </option>
+  </component>
+</project>
@@ -2,6 +2,16 @@
 <project version="4">
  <component name="CompilerConfiguration">
    <option name="BUILD_PROCESS_HEAP_SIZE" value="3000" />
-    <bytecodeTargetLevel target="11" />
+    <bytecodeTargetLevel target="11">
+      <module name="prog8.codeGenExperimental" target="17" />
+      <module name="prog8.codeGenExperimental.main" target="17" />
+      <module name="prog8.codeGenExperimental.test" target="17" />
+      <module name="prog8.codeGenM68k" target="17" />
+      <module name="prog8.codeGenM68k.main" target="17" />
+      <module name="prog8.codeGenM68k.test" target="17" />
+      <module name="prog8.codeGenNew6502" target="17" />
+      <module name="prog8.codeGenNew6502.main" target="17" />
+      <module name="prog8.codeGenNew6502.test" target="17" />
+    </bytecodeTargetLevel>
  </component>
 </project>
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="GradleMigrationSettings" migrationVersion="1" />
+  <component name="GradleSettings">
+    <option name="linkedExternalProjectsSettings">
+      <GradleProjectSettings>
+        <option name="distributionType" value="LOCAL" />
+        <option name="externalProjectPath" value="$PROJECT_DIR$" />
+        <option name="modules">
+          <set>
+            <option value="$PROJECT_DIR$" />
+            <option value="$PROJECT_DIR$/codeCore" />
+            <option value="$PROJECT_DIR$/codeGenCpu6502" />
+            <option value="$PROJECT_DIR$/codeGenIntermediate" />
+            <option value="$PROJECT_DIR$/codeOptimizers" />
+            <option value="$PROJECT_DIR$/compiler" />
+            <option value="$PROJECT_DIR$/compilerAst" />
+            <option value="$PROJECT_DIR$/intermediate" />
+            <option value="$PROJECT_DIR$/languageServer" />
+            <option value="$PROJECT_DIR$/parser" />
+            <option value="$PROJECT_DIR$/simpleAst" />
+            <option value="$PROJECT_DIR$/virtualmachine" />
+          </set>
+        </option>
+        <option name="myGradleHome" value="/usr/share/java/gradle" />
+      </GradleProjectSettings>
+    </option>
+  </component>
+</project>
@@ -534,7 +534,6 @@
    <inspection_tool class="GroovyUnusedDeclaration" enabled="false" level="WARNING" enabled_by_default="false" />
    <inspection_tool class="GroovyUnusedIncOrDec" enabled="false" level="WARNING" enabled_by_default="false" />
    <inspection_tool class="GroovyVariableNotAssigned" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="GrpcSchemes" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
    <inspection_tool class="Guava" enabled="true" level="WARNING" enabled_by_default="true" />
    <inspection_tool class="HardcodedFileSeparators" enabled="true" level="WARNING" enabled_by_default="true">
      <option name="m_recognizeExampleMediaType" value="false" />
@@ -585,20 +584,6 @@
    </inspection_tool>
    <inspection_tool class="HtmlUnknownTarget" enabled="false" level="WARNING" enabled_by_default="false" />
    <inspection_tool class="HtmlWrongAttributeValue" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpClientDuplicateImportInspection" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpClientInappropriateProtocolUsageInspection" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpClientRunRequestNameInspection" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpClientUnresolvedAuthId" enabled="false" level="ERROR" enabled_by_default="false" />
-    <inspection_tool class="HttpClientUnresolvedVariable" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestContentLengthIsIgnored" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestCustomHttpMethodInspection" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestEnvironmentAuthConfigurationValidationInspection" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestJsonBodyInspection" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestPlaceholder" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestRequestSeparatorJsonBodyInspection" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestRequestSeparatorXmlBodyInspection" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestRequestSeparatorYamlBodyInspection" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
-    <inspection_tool class="HttpRequestWhitespaceInsideRequestTargetPath" enabled="false" level="WEAK WARNING" enabled_by_default="false" />
    <inspection_tool class="IOResource" enabled="true" level="WARNING" enabled_by_default="true">
      <option name="ignoredTypesString" value="java.io.ByteArrayOutputStream,java.io.ByteArrayInputStream,java.io.StringBufferInputStream,java.io.CharArrayWriter,java.io.CharArrayReader,java.io.StringWriter,java.io.StringReader" />
      <option name="insideTryAllowed" value="false" />
@@ -629,7 +614,6 @@
      <option name="reportPerFile" value="true" />
      <option name="kotlinOnly" value="true" />
    </inspection_tool>
-    <inspection_tool class="IncorrectHttpHeaderInspection" enabled="false" level="WARNING" enabled_by_default="false" />
    <inspection_tool class="IncrementDecrementUsedAsExpression" enabled="true" level="WARNING" enabled_by_default="true" />
    <inspection_tool class="IndexZeroUsage" enabled="false" level="WARNING" enabled_by_default="false" />
    <inspection_tool class="InfiniteLoopJS" enabled="false" level="WARNING" enabled_by_default="false" />
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RemoteRepositoriesConfiguration">
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Maven Central repository" />
+      <option name="url" value="https://repo1.maven.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="80ae155e-b222-4ca0-92cf-6041a298e78a" />
+      <option name="name" value="80ae155e-b222-4ca0-92cf-6041a298e78a" />
+      <option name="url" value="https://jitpack.io" />
+    </remote-repository>
+  </component>
+</project>
@@ -7,13 +7,14 @@
    <option name="jvmTarget" value="11" />
  </component>
  <component name="KotlinCommonCompilerArguments">
-    <option name="apiVersion" value="2.2" />
-    <option name="languageVersion" value="2.2" />
+    <option name="apiVersion" value="2.4" />
+    <option name="languageVersion" value="2.4" />
  </component>
  <component name="KotlinCompilerSettings">
-    <option name="additionalArguments" value="-Xwhen-guards -jvm-default=no-compatibility" />
+    <option name="additionalArguments" value="-jvm-default=no-compatibility" />
  </component>
  <component name="KotlinJpsPluginSettings">
-    <option name="version" value="2.2.0" />
+    <option name="externalSystemId" value="Gradle" />
+    <option name="version" value="2.4.10" />
  </component>
 </project>
@@ -1,23 +0,0 @@
-<component name="libraryTable">
-  <library name="KotlinJavaRuntime" type="repository">
-    <properties maven-id="org.jetbrains.kotlin:kotlin-stdlib-jdk8:2.2.21" />
-    <CLASSES>
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk8/2.2.21/kotlin-stdlib-jdk8-2.2.21.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib/2.2.21/kotlin-stdlib-2.2.21.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/13.0/annotations-13.0.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk7/2.2.21/kotlin-stdlib-jdk7-2.2.21.jar!/" />
-    </CLASSES>
-    <JAVADOC>
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk8/2.2.21/kotlin-stdlib-jdk8-2.2.21-javadoc.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib/2.2.21/kotlin-stdlib-2.2.21-javadoc.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/13.0/annotations-13.0-javadoc.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk7/2.2.21/kotlin-stdlib-jdk7-2.2.21-javadoc.jar!/" />
-    </JAVADOC>
-    <SOURCES>
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk8/2.2.21/kotlin-stdlib-jdk8-2.2.21-sources.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib/2.2.21/kotlin-stdlib-2.2.21-sources.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/13.0/annotations-13.0-sources.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk7/2.2.21/kotlin-stdlib-jdk7-2.2.21-sources.jar!/" />
-    </SOURCES>
-  </library>
-</component>
@@ -1,18 +0,0 @@
-<component name="libraryTable">
-  <library name="antlr.antlr4" type="repository">
-    <properties maven-id="org.antlr:antlr4:4.13.2">
-      <exclude>
-        <dependency maven-id="com.ibm.icu:icu4j" />
-      </exclude>
-    </properties>
-    <CLASSES>
-      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/antlr4/4.13.2/antlr4-4.13.2.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/antlr4-runtime/4.13.2/antlr4-runtime-4.13.2.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/antlr-runtime/3.5.3/antlr-runtime-3.5.3.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/ST4/4.3.4/ST4-4.3.4.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/abego/treelayout/org.abego.treelayout.core/1.0.3/org.abego.treelayout.core-1.0.3.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -1,13 +0,0 @@
-<component name="libraryTable">
-  <library name="eclipse.lsp4j" type="repository">
-    <properties maven-id="org.eclipse.lsp4j:org.eclipse.lsp4j:0.24.0" />
-    <CLASSES>
-      <root url="jar://$MAVEN_REPOSITORY$/org/eclipse/lsp4j/org.eclipse.lsp4j/0.24.0/org.eclipse.lsp4j-0.24.0.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/org/eclipse/lsp4j/org.eclipse.lsp4j.jsonrpc/0.24.0/org.eclipse.lsp4j.jsonrpc-0.24.0.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/com/google/code/gson/gson/2.13.1/gson-2.13.1.jar!/" />
-      <root url="jar://$MAVEN_REPOSITORY$/com/google/errorprone/error_prone_annotations/2.38.0/error_prone_annotations-2.38.0.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -1,23 +0,0 @@
-<component name="libraryTable">
-  <library name="io.kotest.framework.datatest" type="repository">
-    <properties maven-id="io.kotest:kotest-framework-datatest:5.9.1" />
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-      <root url="jar://$MAVEN_REPOSITORY$/io/github/java-diff-utils/java-diff-utils/4.12/java-diff-utils-4.12.jar!/" />
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-    <JAVADOC />
-    <SOURCES />
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@@ -1,41 +0,0 @@
-<component name="libraryTable">
-  <library name="io.kotest.runner.junit5.jvm" type="repository">
-    <properties maven-id="io.kotest:kotest-runner-junit5-jvm:5.9.1" />
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-    <SOURCES />
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@@ -1,10 +0,0 @@
-<component name="libraryTable">
-  <library name="jetbrains.kotlinx.cli.jvm" type="repository">
-    <properties include-transitive-deps="false" maven-id="org.jetbrains.kotlinx:kotlinx-cli-jvm:0.3.6" />
-    <CLASSES>
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-    <JAVADOC />
-    <SOURCES />
-  </library>
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@@ -1,20 +0,0 @@
-<component name="libraryTable">
-  <library name="michael.bull.kotlin.result.jvm" type="repository">
-    <properties maven-id="com.michael-bull.kotlin-result:kotlin-result-jvm:2.1.0" />
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@@ -20,6 +20,7 @@
  <component name="Black">
    <option name="sdkName" value="Python 3.11" />
  </component>
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
  <component name="FrameworkDetectionExcludesConfiguration">
    <type id="Python" />
  </component>
@@ -2,24 +2,9 @@
 <project version="4">
  <component name="ProjectModuleManager">
    <modules>
-      <module fileurl="file://$PROJECT_DIR$/beanshell/beanshell.iml" filepath="$PROJECT_DIR$/beanshell/beanshell.iml" />
      <module fileurl="file://$PROJECT_DIR$/benchmark-program/benchmark-program.iml" filepath="$PROJECT_DIR$/benchmark-program/benchmark-program.iml" />
-      <module fileurl="file://$PROJECT_DIR$/codeCore/codeCore.iml" filepath="$PROJECT_DIR$/codeCore/codeCore.iml" />
-      <module fileurl="file://$PROJECT_DIR$/codeGenCpu6502/codeGenCpu6502.iml" filepath="$PROJECT_DIR$/codeGenCpu6502/codeGenCpu6502.iml" />
-      <module fileurl="file://$PROJECT_DIR$/codeGenExperimental/codeGenExperimental.iml" filepath="$PROJECT_DIR$/codeGenExperimental/codeGenExperimental.iml" />
-      <module fileurl="file://$PROJECT_DIR$/codeGenIntermediate/codeGenIntermediate.iml" filepath="$PROJECT_DIR$/codeGenIntermediate/codeGenIntermediate.iml" />
      <module fileurl="file://$PROJECT_DIR$/codeGenVirtual/codeGenVirtual.iml" filepath="$PROJECT_DIR$/codeGenVirtual/codeGenVirtual.iml" />
-      <module fileurl="file://$PROJECT_DIR$/codeOptimizers/codeOptimizers.iml" filepath="$PROJECT_DIR$/codeOptimizers/codeOptimizers.iml" />
-      <module fileurl="file://$PROJECT_DIR$/compiler/compiler.iml" filepath="$PROJECT_DIR$/compiler/compiler.iml" />
-      <module fileurl="file://$PROJECT_DIR$/compilerAst/compilerAst.iml" filepath="$PROJECT_DIR$/compilerAst/compilerAst.iml" />
-      <module fileurl="file://$PROJECT_DIR$/docs/docs.iml" filepath="$PROJECT_DIR$/docs/docs.iml" />
-      <module fileurl="file://$PROJECT_DIR$/examples/examples.iml" filepath="$PROJECT_DIR$/examples/examples.iml" />
-      <module fileurl="file://$PROJECT_DIR$/intermediate/intermediate.iml" filepath="$PROJECT_DIR$/intermediate/intermediate.iml" />
-      <module fileurl="file://$PROJECT_DIR$/languageServer/languageServer.iml" filepath="$PROJECT_DIR$/languageServer/languageServer.iml" />
-      <module fileurl="file://$PROJECT_DIR$/parser/parser.iml" filepath="$PROJECT_DIR$/parser/parser.iml" />
      <module fileurl="file://$PROJECT_DIR$/.idea/modules/prog8.iml" filepath="$PROJECT_DIR$/.idea/modules/prog8.iml" />
-      <module fileurl="file://$PROJECT_DIR$/simpleAst/simpleAst.iml" filepath="$PROJECT_DIR$/simpleAst/simpleAst.iml" />
-      <module fileurl="file://$PROJECT_DIR$/virtualmachine/virtualmachine.iml" filepath="$PROJECT_DIR$/virtualmachine/virtualmachine.iml" />
    </modules>
  </component>
 </project>
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
  <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+    <mapping directory="" vcs="Git" />
  </component>
 </project>
@@ -0,0 +1,5 @@
+---
+description: Startup workflow to load project context
+---
+
+1. Read the file `AGENTS.md` in the project root as initial system prompt to build context and instructions about the project structure, module descriptions, and development commands.
@@ -0,0 +1,5 @@
+# Agent Instructions
+
+- The file `AGENTS.md` MUST be loaded as the very first step of every session, if it isn't already loaded by the system.
+- Follow all project-specific guidelines and information provided in `AGENTS.md`.
+- Ensure all automated tasks and code generations adhere to the language rules and architectural decisions described in `AGENTS.md`.
@@ -0,0 +1,31 @@
+{
+  "context": {
+    "fileName": "AGENTS.md"
+  },
+  "$version": 3,
+  "permissions": {
+    "allow": [
+      "Bash(prog8c *)",
+      "Bash(gradle *)",
+      "Bash(mkdir *)",
+      "Bash(ls *)",
+      "Bash(cat *)",
+      "Bash(find *)",
+      "Bash(sed *)",
+      "Bash(grep *)",
+      "Bash(xargs *)",
+      "Bash(wc *)",
+      "Bash(diff *)",
+      "Bash(paste *)",
+      "Bash(echo *)",
+      "Bash(cp *)",
+      "Bash(time)",
+      "Bash(kotlinc *)",
+      "Bash(python3 *)",
+      "Bash(jar *)",
+      "Bash(od *)",
+      "Bash(xxd *)",
+      "Bash(gcc *)"
+    ]
+  }
+}
@@ -0,0 +1,355 @@
+# CRITICAL RULES - MUST FOLLOW
+
+## RESPONSES
+
+- Keep responses concise and to the point - unless the user asks otherwise
+
+## PLANNING MODE
+
+- Always ask clarifying questions
+- Never assume design, tech stack or features
+- Use deep-dive sub-agents to assist with research
+- Use deep-dive sub-agents to review the different aspects of your plan before presenting to the user
+
+## CHANGE / EDIT MODE
+
+- Never implement features yourself when possible - use sub-agents!
+- Identify changes from the plan that can be implemented in parallel, and use sub-agents to implement the features efficiently
+- When using sub-agents to implement features, act as a coordinator only
+- Use the best model for the task - premium models for complex tasks (like coding) and mid-tier models for simpler tasks, like documentation
+- After completing features (large or small), always run commands like lint, type check and next build to check code quality
+
+## Project Overview
+- This project is a compiler for the Prog8 programming language.
+- Prog8 is a programming language primarily targeting 8-bit retro systems with the 6502 CPU, such as the Commodore 64, Commodore 128, and Commander X16.
+- The compiler has a 6502 code generator backend, and an IR code generator.
+- The IR code is meant to be used in a new machine specific code generator backend (primarily 6502 but maybe 68000 as well later)
+- The compiler includes a simple 'virtual machine' that can execute the IR code directly via interpretation.
+- Prog8 source files have .p8 extension – these are *not* LUA or PICO-8 source files in this case!
+- Prog8 source files are a "module" that can contain one or more "blocks". They can also import other modules, from internal library files or from source files on the filesystem.
+- The prog8 compiler is written mostly in Kotlin, those files have the .kt extension.
+- The standard library is mostly written in Prog8 and assembly code, and can be found in the "compiler" module, in the 'res/prog8lib' directory.
+- **Library Reference**: For a quick overview of all available modules, routines, and their signatures, **consult the skeleton files (symboldumps)** in `docs/source/_static/symboldumps/`. They are named `skeletons-<target>.txt`.
+- Kotlin version 2.4 is used for the compiler implementation.
+- Java 17 is used as Java runtime version.
+- ANTLR4 version 4.13 is used for the parser implementation.
+- Dependent library versions can be found in 'build.gradle.kts' and in the IntelliJ IDEA configuration files in .idea/libraries
+- The compiler main entrypoint is in the "compiler" module, in src/prog8/CompilerMain.kt
+
+## Compilation Flow (High-Level)
+```
+Source → parseMainModule() → processAst() → optimizeAst() → postprocessAst()
+       → Simple AST → Code Generator → Assembly → .prg
+```
+
+**Key phases in `compiler/src/prog8/compiler/Compiler.kt`:**
+- `parseMainModule()` - Import modules, parse to Compiler AST
+- `processAst()` - Semantic analysis, constant folding, type casting, validation
+- `optimizeAst()` - Dead code elimination, inlining, statement optimization
+- `postprocessAst()` - Memory layout, final transformations
+- Code generation – Simple AST → IR or 6502 assembly
+
+**Understanding this order is important:** For example, `ConstantIdentifierReplacer` runs during `processAst()`, so by the time `AstChecker` runs at the end of that phase, identifier references have already been replaced with their actual values.
+
+### Target Differences
+- **CPU instruction set differences**: Only the CommanderX16 target (cx16) can use 65C02 instructions such as STZ. The other targets (C64, C128, PET32) can only use original 6502 instructions.
+- When writing or understanding assembly code, load the `asm6502-coder` skill for 64tass syntax and conventions.
+
+
+## DEBUGGING TIP: Use `-noopt` to isolate problems
+When investigating a possible code generation problem (both IR and 6502), **FIRST try compiling the program with the `-noopt` switch** to disable most of the compiler optimizations.
+- **Problem gone with `-noopt`**: Issue is in **optimization phases** (`optimizeAst()`, `UnusedCodeRemover`, `Inliner`, etc.)
+- **Problem persists with `-noopt`**: Issue is in **parsing, semantic analysis, symboltable, or the regular code generation path**.
+
+This way you can determine if the problem is caused by a faulty optimization step, or just occurs in the regular code generation path.
+
+## DEBUGGING TIP: Use `-compareir` to see what changed
+When investigating optimization-related issues or tracking regressions:
+```bash
+# Compile without optimizations (baseline)
+prog8c -target virtual -noopt -out dir program.p8
+
+# Compile with optimizations and compare
+prog8c -target virtual -compareir dir/program_noopt.p8ir program.p8
+```
+**Output shows:**
+- Instruction/chunk/register count changes with percentages
+- First 10 actual instruction differences
+- Helps identify which optimization transformed the code
+
+## DEBUGGING TIP: Use `-vmtrace` to trace execution
+When debugging VM execution or control flow issues:
+```bash
+prog8c -target virtual -vm program.p8ir -vmtrace
+prog8c -target virtual -emu -vmtrace program.p8
+```
+**Output format:** `[chunkName:instructionIndex] instruction`
+- Shows each executed IR instruction with location
+- Useful for understanding control flow and finding where execution diverges
+- **Only works on virtual target**
+
+## Typical debugging workflow:
+1. **Quick check:** `-check` for syntax errors
+2. **Isolate:** `-noopt` to determine if problem is optimizer-related
+3. **Compare:** `-compareir` to see what instructions changed
+4. **Trace:** `-vmtrace` to watch actual execution flow
+5. **Deep dive:** `-printast1` / `-printast2` for compiler internals
+
+## IMPORTANT: SymbolTable cachedFlat cache
+The `SymbolTable` class has a **cached `flat` property** for fast symbol lookups.
+
+**CRITICAL:** If you modify the AST **after** SymbolTable construction, you **MUST** call `symbolTable.resetCachedFlat()` or lookups will fail!
+
+## IMPORTANT: Virtual Target (IR Codegen) Issues
+For problems that **ONLY occur with the 'virtual' target**, **ONLY modify these modules**:
+- `codeGenIntermediate` - IR code generator
+- `intermediate` - IR representation and file I/O  
+- `virtualmachine` - VM that executes IR code
+
+**DO NOT modify** `compilerAst`, `simpleAst`, `codeGenCpu6502`, etc. The IR codegen has its own separate handling for symbol tables, AST transformations, and unused code removal.
+
+## IMPORTANT: Compiler Crashes Must Be Fixed in the Compiler
+A Kotlin/Java crash in the compiler itself (as opposed to a compilation error in the user's program) indicates a bug in the compiler code. **Such crashes should NEVER be worked around by modifying the Prog8 source file that triggered them.**
+
+Instead, always fix the bug in the compiler's Kotlin code. The user's program is correct - the compiler needs to handle it properly.
+
+Steps when encountering a compiler crash:
+1. Create a minimal reproduction case of the Prog8 source that triggers the crash
+2. Debug the compiler to find the root cause in the Kotlin code
+3. Fix the compiler bug, not the user program
+
+## CRITICAL: NO FORMATTING
+- DO NOT change indentation and formatting of lines that are not being modified. NEVER run formatters (black, ruff, prettier, etc.) after edits,
+- .editorconfig handles basic formatting (indentation, line endings, whitespace)
+- Make ONLY the requested changes, touch nothing else
+- **NO EMOJI in user documentation**. Do not use emoji or decorative unicode symbols in documentation files. Functional unicode symbols are acceptable when they serve a clear purpose (e.g., → for arrows, ± for plus-minus, × for multiplication, ° for degrees). Avoid decorative emoji like ❌ ✅ ⚠️ 🎉 etc.
+
+### Code Style Guidelines
+**Minimal comments when making changes**: When modifying existing code, add only essential comments that explain *why* a change was made or document non-obvious behavior. **Do not add verbose comments** that restate what the code does; let the code speak for itself. Existing extensive comments should be preserved, but new changes should have minimal commentary.
+
+**Kotlin string `$` handling**: The `$` character is special in Kotlin string literals (string interpolation). If you need a literal `$` character, use Kotlin's `$$"..."` interpolation prefix instead of backslash escaping (`\$`) or `${'$'}`. The `$$"..."` syntax is a fairly recent Kotlin feature that avoids nasty escaping. For example:
+```kotlin
+val bill = $$"The value is $3.99"
+```
+
+
+## Prog8 language information
+
+When the task involves writing or understanding `.p8` (Prog8 source) or `.p8ir` (Prog8 intermediate representation) files, **load the `prog8-coder` skill** — it contains the full language reference, syntax rules, and standard library guidance.
+
+## Project Module Descriptions
+- `compiler` - Main compiler entrypoint (src/prog8/CompilerMain.kt)
+- `compilerAst` - Complex AST where most optimizations run
+- `simpleAst` - Simplified AST used by code generator backends
+- `parser` - ANTLR4 parser implementation
+- `codeCore` - Core code generation utilities
+- `codeGenCpu6502` - 6502 assembly code generator backend
+- `codeGenIntermediate` - Intermediate representation (IR) code generator
+- `codeGenVirtual` - Virtual machine code generator backend
+- `codeOptimizers` - Optimization passes
+- `intermediate` - IR components
+- `virtualmachine` - VM that executes IR code
+- `languageServer` - Language Server Protocol implementation
+- `docs` - Documentation files
+- `examples` - Example Prog8 programs
+
+## Key Information
+- never read the files and directories that are ignored via the .aiignore and .gitignore files (EXCEPT when it is a folder for agent config such as .junie, .opencode, .qwen or .agent)
+- never perform any git source control write/update/add/commit/branch operations. Read and status operations are allowed.
+- **git log/history queries can be useful** for understanding when/why a feature was added or tracking down when a bug was introduced, but for locating code use grep_search or glob instead.
+- Architecture decisions: separation of frontend/parser, IR intermediate representation, multiple backends
+
+# Dev environment tips
+
+## Development Workflows
+
+**1. Testing your own Prog8 programs** (no compiler changes):
+- No rebuild needed - just run `prog8c` directly
+- Edit your `.p8` file → compile/run → check stdout output
+- Example: `prog8c -target virtual -emu myprogram.p8`
+
+**2. Testing compiler or standard library changes**:
+- Rebuild required after every change to `.kt`, `.p8`, or `.asm` files in the compiler project
+- Workflow: edit source → `gradle installdist installshadowdist` → test with `prog8c`
+- Example: fix bug in `CodeGen6502.kt` → rebuild → `prog8c -target cx16 test.p8`
+
+## Building and Installing the Compiler
+- use the system installed gradle command instead of the gradle wrapper.
+
+### Quick compile check (NO tests)
+- **After changing compiler Kotlin source (.kt files)**: Use `gradle :compiler:compileKotlin --console=plain` to quickly check for syntax/compile errors
+- This compiles the compiler but **skips running tests**, this is much faster than `gradle build`
+- **Note:** This does NOT install the compiler - use `gradle installdist installshadowdist --console=plain` after to actually use your changes
+
+### When you MUST rebuild AND reinstall the compiler
+
+**After ANY change to:**
+1. **Kotlin compiler source code** (`.kt` files in any module, or the `.g4` grammar file)
+2. **Standard library Prog8 files** (`compiler/res/prog8lib/**/*.p8`)
+3. **Standard library assembly files** (`compiler/res/prog8lib/**/*.asm`)
+
+**Run:** `gradle installdist installshadowdist --console=plain`
+
+**Why:** The standard library files (.p8 and .asm) are embedded into the compiler JAR during the build. Changes to these files are NOT picked up by simply running `prog8c` - you MUST rebuild and reinstall for your changes to take effect.
+
+**Without this step, your changes will NOT be reflected when running `prog8c`!**
+- This compiles AND installs, but still skips running tests (faster than `gradle build`)
+
+### When to run full build with tests
+- **Before final verification**: Always run `gradle build` to ensure all tests pass
+- **After major refactoring**: Run `gradle build` to catch regressions
+- **When debugging test failures**: Use `gradle test --tests "*TestName*"` for specific tests
+- **When working on a standalone codegen module** (one that reads `.p8ir` files): Run `gradle :<module>:test --console=plain` instead of full `gradle build`. Compiler unit tests are irrelevant for IR-level changes. Do run full `gradle build` before final verification.
+
+### Build command summary
+
+| Command | When to use | Time |
+|---------|-------------|------|
+| `gradle :compiler:compileKotlin --console=plain` | Quick syntax check (no tests) | ~10-20s |
+| `gradle installdist installshadowdist --console=plain` | After compiler changes (to use them) | ~10-20s |
+| `gradle build --console=plain` | Before commits, after major changes | ~45-60s |
+| `gradle test --tests "*Name*" --console=plain` | Run specific tests | ~5-30s |
+
+**Note:** Use system `gradle` command, not wrapper. Run `gradle clean` if you suspect stale artifacts.
+
+## Using the Compiler (prog8c)
+- the prog8c compiler executable can be found in the compiler/build/install/prog8c/bin folder (this is already added to the shell's path)
+- **the `-check` switch performs a quick syntax/semantic check only; it will NOT produce any output files (no .prg, .asm, etc.)**. Use it only for fast error checking during development.
+- **the `-noopt` switch DISABLES all optimizations** - useful for debugging to determine if a problem is caused by the optimizer. **Optimizations are ENABLED by default** (no flag needed).
+- **prog8c uses single-dash command line options** (e.g., `-target`, `-noopt`, `-check`), NOT double-dash (`--target` is invalid).
+- **the `-printast1` switch prints out the internal Compiler AST** after parsing and semantic analysis.
+- **the `-printast2` switch prints out the optimized Simple AST** just before it goes to the code generator. This is useful for debugging optimizer issues.
+- **the `-out outdir` switch sets an alternative output directory** for compiled files (.prg, .asm, .list, etc.). **By default, output files are written to the same directory as the source file**.
+- **Other useful flags**: `-quiet` (suppress messages), `-warnimplicitcasts` (warn on implicit type widening), `-daemon` (keep a background compiler process alive — must be passed on every invocation)
+
+### Compilation Output Files
+- `*.prg` - The final compiled program file for the target system (e.g., Commander X16)
+- `*.asm` - Generated assembly code from the Prog8 source
+- `*.list` - Generated full assembly listing file from the Prog8 source
+- `*.p8ir` - Intermediate representation file, can be executed in the Virtual Machine
+- `*.vice-mon-list` - Vice emulator monitor list file for debugging
+
+### Execution Examples
+- `prog8c -target targetname input.p8` - Compile a Prog8 source file "input.p8" for the given target (cx16, c64, pet32, c128, virtual)
+- `prog8c -target targetname -emu input.p8` - Compile and execute a prog8 file in the emulator for the given target (cx16, c64, pet32, c128, virtual)
+- `prog8c -vm input.p8ir` - Execute an existing prog8 program, compiled in IR form, in the Virtual Machine
+
+### Library Tools
+- **Library search**: `prog8c -libsearch <regex>` — search for a regex pattern in the embedded stdlib files. Extremely useful to quickly find library routines, variables, or signatures (e.g., `prog8c -libsearch "txt\."` lists all textio routines)
+- **Library dump**: `prog8c -libdump <dir>` — extract all embedded library source files into a directory for direct inspection
+
+## Testing and Verification
+
+- Never assume your changes simply work, always test!
+- If the project does not have any testing tools, scripts, MCP tools, skills, etc. available for testing, ask the user whether testing should be skipped.
+
+### Automated Tests (gradle)
+Always use the `--console=plain` flag with these commands to avoid messing up the agent's text interface.
+- `gradle build --console=plain` - Full build including all tests (about 50s)
+- `gradle :compiler:test --console=plain` - Run only compiler tests (faster)
+- `gradle :compiler:test --tests "prog8tests.compiler.TestOptimization" --console=plain` - Run specific test class
+
+Note: By default, Gradle only shows failed tests. Passed and skipped tests are silent.
+
+**⚠️ CRITICAL: Test Filtering Patterns - Read This First!**
+
+Gradle's `--tests` filter has **strict rules** that are easy to get wrong:
+
+| Pattern | Example | Works?        |
+|---------|---------|---------------|
+| **Full class name** | `--tests "prog8tests.compiler.TestOptimization"` | **USE THIS**  | 
+| Wildcard at END | `--tests "prog8tests.compiler.Test*"` | Yes           |
+| Wildcard on package | `--tests "prog8tests.compiler.*"` | Yes           |
+| **Wildcard at START** | `--tests "*TestOptimization"` | FAILS         |
+| Test description | `--tests "*Optimization*inline*"` | FAILS         |
+
+**Why the restrictions?** Gradle's `--tests` filter matches **fully qualified class names only**. Wildcards work as **suffixes** (e.g., `Test*`) but NOT as prefixes (e.g., `*Test`). KoTest test names like `"inline multi-value void"` are _descriptions_, not method names, so you cannot filter by them.
+
+**To find failing tests after a run:**
+```bash
+# Check XML results (reliable)
+grep "<failure" compiler/build/test-results/test/*.xml
+
+# Or check HTML report (most reliable)
+cat compiler/build/reports/tests/test/index.html
+
+# For test compilation errors
+gradle :compiler:compileTestKotlin --info 2>&1 | grep "^e:"
+```
+
+**Additional notes:**
+- Unit tests use KoTest (FunSpec style)
+- Tests are in the "compiler" module's `test` directory (and some other modules)
+- Test config is in root `build.gradle.kts`; tests run in parallel
+- **When writing test programs**, add at the top: `%zeropage basicsafe` and `%option no_sysinit`
+- When a test fails, the output shows "There were failing tests. See the report at:" - **read that HTML report**
+
+### Compiler Unit Test Snippets
+Prog8 code snippets embedded in the compiler's own Kotlin unit tests (e.g., in `TestAstChecks.kt`, `TestOptimization.kt`) follow different rules from standalone programs:
+- **Keep self-contained** — avoid `%import` directives (test setup may not have library search path configured)
+- **Use `cx16` target** (not `virtual`, unless specifically testing the VM)
+- **Set `writeAssembly=false`** if the test only checks generated AST (much faster)
+- **Set `optimize=false`** by default for these snippets
+- **Do NOT use** the `%encoding iso` / `txt.iso()` / `sys.poweroff_system()` pattern — that's only for real CX16 emulator runs
+
+### Testing Assembly Output
+When testing generated assembly in Kotlin tests:
+- **NEVER dump raw assembly in string assertions** (e.g., `asm shouldContain "jsr label"`). On failure, this dumps the ENTIRE assembly listing into test logs.
+- **Instead, parse into lines and check specific properties:**
+  ```kotlin
+  val lines = asm.lines().map { it.trim() }
+  lines.any { it == "lda #42" } shouldBe true
+  lines.count { it.startsWith("jsr") } shouldBe 0
+  ```
+- Prefer `lines.any { ... }` for existence checks and `lines.count { ... } shouldBe 0` for absence checks.
+
+### Manual Verification & Emulators
+
+**Testing tip**: When writing and testing Prog8 programs, **use the `virtual` target** (e.g., `prog8c -target virtual -emu input.p8` or `prog8c -vm input.p8ir`). This is the preferred way to test because the virtual target can easily write output to stdout, making it simple to verify program behavior and check results.
+
+**CX16 output verification**: Use `x16emu -echo iso -run -prg input.prg` to echo screen output to stdout **and auto-start the program**. The `-run` flag is **critical**: without it, the program loads but doesn't execute, so you'll see no output. Pipe through `strings` or `grep` to filter: `x16emu -echo iso -run -prg input.prg 2>&1 | grep -E "(PASS|FAIL)"`.
+**IMPORTANT**: Always add `%encoding iso` at the top of your source file and call `txt.iso()` in `start()`. This prevents PETSCII→ISO charset translation errors that garble uppercase/special characters and make output unreadable:
+```prog8
+%encoding iso
+%import textio
+main { sub start() { txt.iso(); txt.print("PASS\n") } }
+```
+**IMPORTANT: Always use `sys.poweroff_system()` to exit the CX16 emulator cleanly!** Add `sys.poweroff_system()` at the end of your main program block - this exits x16emu automatically in most cases.
+**Note:** The `sys` module is always available, there is no need to import it ever.
+
+**Commodore 64 (x64sc)**: `x64sc input.prg` - run an existing compiled program in the Commodore-64 emulator. Ignore any errors and warnings, because the emulator doesn't produce any output on STDOUT.
+
+### actual 6502 CPU simulation tests
+For high-fidelity functional verification of generated 6502 code without a full emulator, you can use the `ksim65` simulator in your unit tests. This allows executing the compiled machine code and asserting on memory or register states.
+- Use the `simulate()` extension function on a `CompilationResult`.
+- See `prog8tests.codegeneration.TestExecution6502` for examples.
+- Both 6502 and 65C02 CPUs can be simulated.
+- The simulator supports capturing serial output and handling hardware reset/poweroff signals.
+- There are various assertion helper methods to test on the state of CPU registers, memory contents, etc.
+- Using the simulator is much faster and way more controllable than using a full emulator to run the code.
+- The simulator DOES NOT represent an actual real world machine and has VERY LIMITED hardware devices so it can generally not be used to run full example prorams on.
+
+## Git Operations for File Moves/Deletes
+
+**When renaming or moving git-tracked files, ALWAYS use `git mv`:**
+```bash
+# CORRECT - preserves git history
+git mv old/path/File.kt new/path/File.kt
+
+# WRONG - git sees this as delete + add (loses history)
+mv old/path/File.kt new/path/File.kt
+```
+
+**When deleting git-tracked files, ALWAYS use `git rm`:**
+```bash
+# CORRECT - properly stages the deletion
+git rm path/to/File.kt
+
+# WRONG - git sees this as unstaged deletion
+rm path/to/File.kt
+```
+
+**Why this matters:** `git mv` and `git rm` properly stage the changes and preserve file history. Plain `mv`/`rm` requires git to detect renames heuristically, which may not always work correctly.
+
+## TODO Items
+The file `docs/source/todo.rst` contains a comprehensive list of things that still have to be fixed, implemented, or optimized. **Use this to understand what features are NOT yet available** in the compiler or Prog8 language: if a user asks for something that's on the TODO list, you'll know it's not implemented yet and can explain the limitation.
@@ -1,12 +1,20 @@
-# super simple Makefile to lauch the main gradle targets to build and/or test the prog8 compiler
+# super simple Makefile to launch the main gradle targets to build and/or test the prog8 compiler

 .PHONY: all test

+# Use system gradle if available, otherwise fall back to gradlew wrapper
+# Windows uses 'where' and gradlew.bat, Unix uses 'command -v' and ./gradlew
+ifeq ($(OS),Windows_NT)
+    GRADLE = $(shell where gradle >nul 2>&1 && echo gradle || echo gradlew.bat)
+else
+    GRADLE = $(shell command -v gradle >/dev/null 2>&1 && echo gradle || echo ./gradlew)
+endif
+
 all:
-	gradle installdist installshadowdist
-	@echo "compiler launch script can be found here: compiler/build/install/compiler-shadow/bin/prog8c"
+	$(GRADLE) installdist installshadowdist
+	@echo "compiler launch script can be found here: compiler/build/install/prog8c-shadow/bin/prog8c"

 test:
-	gradle build
-	@echo "compiler launch script can be found here: compiler/build/install/compiler-shadow/bin/prog8c"
+	$(GRADLE) build
+	@echo "compiler launch script can be found here: compiler/build/install/prog8c-shadow/bin/prog8c"

@@ -15,10 +15,12 @@ which aims to provide many conveniences over raw assembly code (even when using

 **Want to buy me a coffee or a pizza perhaps?**

-This project was created over the last couple of years by dedicating thousands of hours of my free time to it, to make it the best I possibly can.
+This project was created over the last couple of years by dedicating a huge amoung of my free time to it, to make it the best I possibly can.
 If you like Prog8, and think it's worth a nice cup of hot coffee or a delicious pizza, 
 you can help me out a little bit over at [ko-fi.com/irmen](https://ko-fi.com/irmen) or [PayPal](https://paypal.me/irmendejong)

+[![JetBrains logo.](https://resources.jetbrains.com/storage/products/company/brand/logos/jetbrains.svg)](https://jb.gg/OpenSource)
+ I am using JetBrains products to develop the Prog8 compiler.

 Documentation
 -------------
@@ -63,8 +65,10 @@ What does Prog8 provide?
 - programs run very fast because it's compiled to native machine code
 - compiled code is very small; much smaller than equivalent C code compiled with CC65, and usually runs faster as well
 - modularity, symbol scoping, subroutines. No need for forward declarations.
+- Can make vars and routines private, as a simple way to restrict access and hide implementation details
 - various data types other than just bytes (16-bit words, long integers, floats, strings)
 - Structs and typed pointers
+- 2D arrays (`matrix[row][col]` syntax)
 - floating point math is supported on certain targets
 - access to most Kernal ROM routines as external subroutine definitions you can call normally
 - tight control over Zeropage usage
@@ -109,8 +113,8 @@ Additional required tools
 -------------------------

 [64tass](https://sourceforge.net/projects/tass64/) - cross assembler. Install this on your shell path.
-A recent .exe version of this tool for Windows can be obtained from my [clone](https://github.com/irmen/64tass/releases) of this project.
-For other platforms it is very easy to compile it yourself (make ; make install).
+If you're on Windows, download a recent .exe from the official repository's file section <https://sourceforge.net/projects/tass64/files/binaries/>.
+For other systems (Mac, Linux) it is very easy to get it via your package manager or to compile it yourself.

 A **Java runtime (jre or jdk), version 11 or newer**  is required to run a prepackaged version of the compiler.
 If you want to build it from source, you'll need a Java SDK + Kotlin 1.3.x SDK (or for instance,
@@ -175,7 +179,7 @@ This code calculates prime numbers using the Sieve of Eratosthenes algorithm::
        }
    }

-when compiled an ran on a C-64 you'll get:
+when compiled and ran on a C-64 you'll get:

 ![c64 screen](docs/source/_static/primes_example.png)

@@ -205,3 +209,10 @@ Here is a performance comparison with various C compilers for the 6502/C64 so yo
 an idea of how Prog8 stacks up.

 [comparison](benchmark-c/benchmark.md)
+
+
+Agent context instructions
+--------------------------
+
+[Agent context instructions](AGENTS.md)
+
@@ -1,24 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" inherit-compiler-output="true">
-    <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-      <excludeFolder url="file://$MODULE_DIR$/build" />
-    </content>
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
-    <orderEntry type="library" name="jetbrains.kotlinx.cli.jvm" level="project" />
-    <orderEntry type="library" name="michael.bull.kotlin.result.jvm" level="project" />
-    <orderEntry type="module-library">
-      <library>
-        <CLASSES>
-          <root url="jar://$MODULE_DIR$/lib/bsh-3.0.0-SNAPSHOT.jar!/" />
-        </CLASSES>
-        <JAVADOC />
-        <SOURCES />
-      </library>
-    </orderEntry>
-  </component>
-</module>
@@ -1,65 +0,0 @@
-import org.jetbrains.kotlin.gradle.dsl.JvmTarget
-
-plugins {
-    id("application")
-    kotlin("jvm")
-}
-
-val serverMainClassName = "prog8lsp.MainKt"
-val applicationName = "prog8-beanshell"
-
-application {
-    mainClass.set(serverMainClassName)
-    description = "Code completions, diagnostics and more for Prog8"
-    // applicationDefaultJvmArgs = listOf("-DkotlinLanguageServer.version=$version")
-    applicationDistribution.into("bin") {
-        filePermissions {
-            user {
-                read=true
-                execute=true
-                write=true
-            }
-            other.execute = true
-            group.execute = true
-        }
-    }
-}
-
-repositories {
-    mavenCentral()
-}
-
-dependencies {
-    implementation(files("lib/bsh-3.0.0-SNAPSHOT.jar"))
-}
-
-configurations.forEach { config ->
-    config.resolutionStrategy {
-        preferProjectModules()
-    }
-}
-
-sourceSets.main {
-    java.srcDir("src")
-    resources.srcDir("resources")
-}
-
-tasks.startScripts {
-    applicationName = "prog8-beanshell"
-}
-
-tasks.register<Exec>("fixFilePermissions") {
-    // When running on macOS or Linux the start script
-    // needs executable permissions to run.
-
-    onlyIf { !System.getProperty("os.name").lowercase().contains("windows") }
-    commandLine("chmod", "+x", "${tasks.installDist.get().destinationDir}/bin/prog8-beanshell")
-}
-
-tasks.installDist {
-    finalizedBy("fixFilePermissions")
-}
-
-tasks.build {
-    finalizedBy("installDist")
-}
@@ -1,48 +0,0 @@
-package prog8beanshell
-
-import java.io.FilterReader
-import java.io.Reader
-
-
-class CommandLineReader(val input: Reader): FilterReader(input)  {
-    private val normal = 0
-    private val lastCharNL = 1
-    private val sentSemi = 2
-    private var state = lastCharNL
-
-    override fun read(): Int {
-        if (state == sentSemi) {
-            this.state = lastCharNL
-            return 10
-        } else {
-            var b = input.read()
-            while(b==13) b = input.read()
-
-            if (b == 10) {
-                if (this.state == lastCharNL) {
-                    b = 59
-                    this.state = sentSemi
-                } else {
-                    this.state = lastCharNL
-                }
-            } else {
-                this.state = normal
-            }
-
-            return b
-        }
-
-    }
-
-    override fun read(buff: CharArray, off: Int, len: Int): Int {
-        val b = read()
-        if (b == -1) {
-            return -1
-        } else {
-            buff[off] = b.toChar()
-            return 1
-        }
-
-    }
-}
-
@@ -1,23 +0,0 @@
-package prog8beanshell
-
-import bsh.FileReader
-import bsh.Interpreter
-
-
-class BeanshellInterpreter {
-
-    fun run(symbols: Map<String, Any>) {
-        val interpreter = Interpreter(CommandLineReader(FileReader(System.`in`)), System.out, System.err, true)
-        interpreter.setExitOnEOF(false)
-        symbols.forEach { (name, value) -> interpreter.set(name, value) }
-        interpreter.run()
-    }
-}
-
-fun main(args: Array<String>) {
-    val i = BeanshellInterpreter()
-    i.run(mapOf(
-        "env" to System.getenv(),
-        "args" to args
-    ))
-}
@@ -2,15 +2,28 @@

 Several benchmarks of https://thred.github.io/c-bench-64/
 have been ported to equivalent Prog8 code and the benchmark results have been penciled in in the graphs below.
+Because they use the CIA timer for measuring the duration of the runs, the code only works on a C64.

 Maybe one day I'll try to integrate the prog8 data properly but their benchmark site is comparing C compilers, which Prog8 clearly is not.

 However conclusions so far (note: these are micro benchmarks so interpret the results as you will!)

-* Prog8 program size is consistently the smallest by a fair bit.
+* Prog8 program size is consistently one of the smallest.
 * Prog8 execution speed places it more or less in the middle of the stack.

 Measured with Prog8 V12.0 .
+Benchmarks ran on a PAL C64 emulated through VICE.
+
+textual results:
+
+| benchmark | size | time     |
+|-----------|------|----------|
+| crc8      | 1568 | 2.0 sec  |
+| crc16     | 1608 | 2.5 sec  |
+| crc32     | 1812 | 4.2 sec  |
+| pow       | 2152 | 11.7 sec |
+| sieve     | 1772 | 22.1 sec |
+| sieve_bit | 1918 | 40.1 sec |


 ![crc8](result-crc8.png)
@@ -0,0 +1,98 @@
+%import textio
+
+cia {
+    ubyte freq
+    const ubyte CNT = 200
+
+    sub calibrate() {
+        txt.print("calibrating frequency: ")
+        tod_init(0)
+        txt.print_ub(tod_freq())
+        txt.print(" hz\n")
+        tod_reset()
+    }
+
+    sub print_time() {
+        uword t = tod_get10()
+        txt.print("(cia) time: ")
+        txt.print_uw(t / 10)
+        txt.chrout('.')
+        txt.print_uw(t % 10)
+        txt.print(" sec.\n")
+    }
+
+    sub tod_reset() {
+        ; set the tod to 0
+        c64.CIA2TODHR = 0
+        c64.CIA2TODMIN = 0
+        c64.CIA2TODSEC = 0
+        c64.CIA2TOD10 = 0
+    }
+
+    sub tod_get10() -> uword {
+        ubyte h, m, s, t
+        uword time
+        h = c64.CIA2TODHR
+        m = c64.CIA2TODMIN
+        s = c64.CIA2TODSEC
+        t = c64.CIA2TOD10
+        time = t
+        time += (s & $0f) * (10 as uword)
+        time += (s >> 4) * (100 as uword)
+        time += (m & $0f) * 600
+        time += (m >> 4) * 6000
+        return time
+    }
+
+    sub tod_init(ubyte f) {
+        if (f == 0)
+            freq = tod_detect_freq()
+        else
+            freq = f
+
+        if (freq == 50)
+            c64.CIA2CRA |= $80
+        else
+            c64.CIA2CRA &= $7f
+    }
+
+    sub tod_freq() -> ubyte {
+        return freq
+    }
+
+    sub tod_detect_freq() -> ubyte {
+        uword cbl
+
+        c64.CIA2CRB = $40  ; stop timer
+        c64.CIA2CRA = $80  ; stop timer
+
+        ; set ta to overflow every 10000 count (~= 10ms)
+        c64.CIA2TAL = $10
+        c64.CIA2TAH = $27
+        c64.CIA2TBL = CNT
+        c64.CIA2TBH = 0
+
+        tod_reset()
+
+        c64.CIA2CRB = $41  ; input from tim1 overflow, continuous, start timer
+        c64.CIA2CRA = $81  ; start timer, continuous tod 50HZ
+
+
+        while c64.CIA2TODSEC == 0 {
+            ; wait for tod to count 1s
+        }
+
+        ;  cal=CIA2.ta_lo;
+        ;  cah=CIA2.ta_hi;
+        cbl = c64.CIA2TBL
+        ;  cbh=CIA2.tb_hi;
+
+        ;  printf("count2 = %d %d %d %d\n",cah, cal, cbh, cbl);
+        ;  printf("elapsed ~= %d0ms\n",CNT-cbl);
+
+        if CNT - cbl > 90
+            return 50
+        else
+            return 60
+    }
+}
@@ -1,5 +1,5 @@
 %import textio
-%import floats
+%import ciatimer

 ; note: Prog8 has a complete CRC16 routine in its library: math.crc16

@@ -7,12 +7,11 @@
 main {
    sub start() {
        txt.lowercase()
+        cia.calibrate()
        test.benchmark_name()
-        cbm.SETTIM(0,0,0)
        test.benchmark()
-        txt.print_f(floats.time() / 60)
-        txt.print(" seconds\n")
        void test.benchmark_check()
+        cia.print_time()
        repeat {}
    }    
 }
@@ -40,12 +39,13 @@ test {

        if crc_result == EXPECTED
        {
-            txt.print(" [OK]")
+            txt.print(" [OK]\n")
            return false
        }

        txt.print(" [FAIL] - expected ")
        txt.print_uwhex(EXPECTED, true)
+        txt.nl()
        return true
    }
    
@@ -1,5 +1,5 @@
 %import textio
-%import floats
+%import ciatimer

 ; note: Prog8 has a complete CRC32 routine in its library: math.crc32

@@ -7,12 +7,11 @@
 main {
    sub start() {
        txt.lowercase()
+        cia.calibrate()
        test.benchmark_name()
-        cbm.SETTIM(0,0,0)
        test.benchmark()
-        txt.print_f(floats.time() / 60)
-        txt.print(" seconds\n")
        void test.benchmark_check()
+        cia.print_time()
        repeat {}
    }    
 }
@@ -40,12 +39,13 @@ test {

        if crc_result == EXPECTED
        {
-            txt.print(" [OK]")
+            txt.print(" [OK]\n")
            return false
        }

        txt.print(" [FAIL] - expected ")
        txt.print_ulhex(EXPECTED, true)
+        txt.nl()
        return true
    }
    
@@ -1,16 +1,15 @@
 %import textio
-%import floats
+%import ciatimer


 main {
    sub start() {
        txt.lowercase()
+        cia.calibrate()
        test.benchmark_name()
-        cbm.SETTIM(0,0,0)
        test.benchmark()
-        txt.print_f(floats.time() / 60)
-        txt.print(" seconds\n")
        void test.benchmark_check()
+        cia.print_time()
        repeat {}
    }    
 }
@@ -36,12 +35,13 @@ test {

        if crc_result == EXPECTED
        {
-            txt.print(" [OK]")
+            txt.print(" [OK]\n")
            return false
        }

        txt.print(" [FAIL] - expected ")
        txt.print_ubhex(EXPECTED, true)
+        txt.nl()
        return true
    }
    
@@ -1,16 +1,16 @@
 %import textio
 %import floats
+%import ciatimer


 main {
    sub start() {
        txt.lowercase()
+        cia.calibrate()
        test.benchmark_name()
-        cbm.SETTIM(0,0,0)
        test.benchmark()
-        txt.print_f(floats.time() / 60)
-        txt.print(" seconds\n")
        void test.benchmark_check()
+        cia.print_time()
        repeat {}
    }    
 }
@@ -1,16 +1,15 @@
 %import textio
-%import floats
+%import ciatimer


 main {
    sub start() {
        txt.lowercase()
+        cia.calibrate()
        test.benchmark_name()
-        cbm.SETTIM(0,0,0)
        test.benchmark()
-        txt.print_f(floats.time() / 60)
-        txt.print(" seconds\n")
        void test.benchmark_check()
+        cia.print_time()
        repeat {}
    }    
 }
@@ -46,12 +45,13 @@ test {

        if prime_count == EXPECTED
        {
-            txt.print(" [OK]")
+            txt.print(" [OK]\n")
            return false
        }

        txt.print(" [FAIL] - expected ")
        txt.print_uw(EXPECTED)
+        txt.nl()
        return true
    }

@@ -1,16 +1,15 @@
 %import textio
-%import floats
+%import ciatimer


 main {
    sub start() {
        txt.lowercase()
+        cia.calibrate()
        test.benchmark_name()
-        cbm.SETTIM(0,0,0)
        test.benchmark()
-        txt.print_f(floats.time() / 60)
-        txt.print(" seconds\n")
        void test.benchmark_check()
+        cia.print_time()
        repeat {}
    }    
 }
@@ -46,12 +45,13 @@ test {

        if prime_count == EXPECTED
        {
-            txt.print(" [OK]")
+            txt.print(" [OK]\n")
            return false
        }

        txt.print(" [FAIL] - expected ")
        txt.print_uw(EXPECTED)
+        txt.nl()
        return true
    }

@@ -7,7 +7,7 @@ adpcm {

        while cbm.RDTIM16()<max_time {
            adpcm.init(0,0)
-            uword @requirezp nibbles_ptr = $a000 ; for benchmark purposes, the exact nibbles don't really matter, so we just take the basic ROM as input
+            uword @requirezp nibbles_ptr = $0800 ; for benchmark purposes, the exact nibbles don't really matter, so we just take this benchmark program itself as input
            repeat 252/2 {
                unroll 2 {
                    ubyte @zp nibble = @(nibbles_ptr)
@@ -113,14 +113,14 @@ btree {
        sub count_node(^^Node r) {
            count++
            if r.left!=0 {
-                sys.pushw(r)
+                pushw(r)
                count_node(r.left)
-                r = sys.popw()
+                r = popw()
            }
            if r.right!=0 {
-                sys.pushw(r)
+                pushw(r)
                count_node(r.right)
-                r = sys.popw()
+                r = popw()
            }
        }
    }
@@ -179,15 +179,15 @@ btree {

        sub process_tree(^^Node r) {
            if r.left!=0 {
-                sys.pushw(r)
+                pushw(r)
                process_tree(r.left)
-                r = sys.popw()
+                r = popw()
            }
            cx16.r0 = r.value
            if r.right!=0 {
-                sys.pushw(r)
+                pushw(r)
                process_tree(r.right)
-                r = sys.popw()
+                r = popw()
            }
        }
    }
@@ -200,18 +200,18 @@ btree {
        sub process_tree(^^Node r, ubyte depth) {
            cx16.r0 = r.value
            if r.left!=0 {
-                sys.pushw(r)
-                sys.push(depth)
+                pushw(r)
+                push(depth)
                process_tree(r.left, depth+1)
-                depth = sys.pop()
-                r = sys.popw()
+                depth = pop()
+                r = popw()
            }
            if r.right!=0 {
-                sys.pushw(r)
-                sys.push(depth)
+                pushw(r)
+                push(depth)
                process_tree(r.right, depth+1)
-                depth = sys.pop()
-                r = sys.popw()
+                depth = pop()
+                r = popw()
            }
        }
    }
@@ -61,8 +61,7 @@ life {
        math.rndseed(12345,9999)
        uword offset = STRIDE+1
        ubyte x
-        ubyte y
-        for y in 0 to HEIGHT-1 {
+        repeat HEIGHT {
            for x in 0 to WIDTH-1 {
                active_world[offset+x] = math.rnd() & 1
            }
@@ -35,12 +35,12 @@ queens {
            if could_place(row, col) {
                board[row] = col
                ; we need to save the local variables row and col.
-                sys.push(row)
-                sys.push(col)
+                push(row)
+                push(col)
                continue_running = place_queen(row + 1)
                ; restore the local variables after the recursive call.
-                col = sys.pop()
-                row = sys.pop()
+                col = pop()
+                row = pop()
                board[row] = 0

                if not continue_running
@@ -26,6 +26,7 @@ main {

    str[20] benchmark_names
    uword[20] benchmark_score
+    str version = "12.1"


    sub start() {
@@ -35,8 +36,10 @@ main {
        txt.color2(1, 6)
        txt.clear_screen()

-        txt.print("\n\n\n  prog8 compiler benchmark tests.\n\n  benchmark version v12\n\n")
-        sys.wait(60)
+        txt.print("\n\n\n  prog8 compiler benchmark tests.\n\n  benchmark version ")
+        txt.print(version)
+        txt.print("\n\n")
+        sys.wait(120)

        benchmark_number = 0

@@ -88,7 +91,10 @@ main {
        txt.color2(1, 6)
        uword total_score
        benchmark_number = 0
-        txt.print("\nscore benchmark (v12)\n\n")
+        txt.print("\nscore benchmark (")
+        txt.print(version)
+        txt.print(")\n\n")
+
        do {
            txt.spc()
            txt.print_uw(benchmark_score[benchmark_number])
@@ -1,11 +1,9 @@
-import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 import org.jetbrains.kotlin.gradle.dsl.JvmDefaultMode
-import org.jetbrains.kotlin.gradle.internal.config.LanguageFeature
-import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget


 plugins {
-    kotlin("jvm") version "2.2.21"
+    kotlin("jvm") version "2.4.10"
 }

 allprojects {
@@ -14,12 +12,13 @@ allprojects {
    repositories {
        mavenLocal()
        mavenCentral()
+        maven { url = uri("https://jitpack.io") }
    }

    kotlin {
        compilerOptions {
-            freeCompilerArgs = listOf("-Xwhen-guards")
-            jvmTarget = JvmTarget.JVM_11
+            freeCompilerArgs = listOf()
+            jvmTarget = JvmTarget.JVM_17
            jvmDefault = JvmDefaultMode.NO_COMPATIBILITY
            // languageVersion.set(KotlinVersion.KOTLIN_2_3)
        }
@@ -32,7 +31,75 @@ allprojects {
    }

    java {
-        targetCompatibility = JavaVersion.VERSION_11
-        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_17
+        sourceCompatibility = JavaVersion.VERSION_17
+    }
+}
+
+// ============================================================================
+// Common Configuration for All Subprojects
+// ============================================================================
+// This avoids duplication in each module's build.gradle.kts
+// ============================================================================
+
+subprojects {
+    // Common dependency exclusions for all subprojects
+    // Note: antlr4 exclusion is done per-module since parser module needs it
+    configurations.all {
+        exclude(group = "com.ibm.icu", module = "icu4j")
+    }
+
+    // Common test dependencies via Kotest BOM (Bill of Materials)
+    // This manages all Kotest module versions centrally
+    dependencies {
+        testImplementation(platform("io.kotest:kotest-bom:6.2.3"))
+        // implementation("com.github.irmen:ksim65:v2.1")
+    }
+
+    // Common sourceSets configuration
+    sourceSets {
+        main {
+            java.srcDir("${project.projectDir}/src")
+            resources.srcDir("${project.projectDir}/res")
+        }
+        test {
+            java.srcDir("${project.projectDir}/test")
+        }
+    }
+
+    // Common test configuration
+    tasks.withType<Test>().configureEach {
+        // Enable JUnit 5 (required for Kotest)
+        useJUnitPlatform()
+
+        // Enable concurrent test execution for Kotest
+        // Set parallelism to number of CPU cores
+        jvmArgs("-Dkotest.framework.parallelism=${Runtime.getRuntime().availableProcessors()}")
+
+        // Disable Kotest autoscan warning
+        jvmArgs("-Dkotest.framework.classpath.scanning.autoscan.disable=true")
+
+        // Enable Gradle's parallel test execution (runs multiple test classes concurrently)
+        // Use 50% of available processors to avoid over-subscription
+        maxParallelForks = (Runtime.getRuntime().availableProcessors() / 2).coerceAtLeast(1)
+
+        // Allow filtering tests via -PtestFilter="*TestName*" from command line
+        // Example: gradle test -PtestFilter="*TestLookup*"
+        val testFilter = project.findProperty("testFilter")?.toString()
+        if(testFilter != null) {
+            filter {
+                includeTestsMatching(testFilter)
+            }
+        }
+
+        // Show test results - only show failures to reduce noise
+        testLogging {
+            events("failed")
+            // Show full exception details for failures
+            exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
+            showExceptions = true
+            showCauses = true
+            showStackTraces = true
+        }
    }
 }
@@ -1,22 +1,11 @@
 plugins {
    kotlin("jvm")
+    `java-test-fixtures`
 }

 dependencies {
    // should have no dependencies to other modules
-    // implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
-    implementation("com.michael-bull.kotlin-result:kotlin-result-jvm:2.1.0")
-}
+    implementation("com.michael-bull.kotlin-result:kotlin-result-jvm:2.3.1")

-sourceSets {
-    main {
-        java {
-            srcDir("${project.projectDir}/src")
-        }
-        resources {
-            srcDir("${project.projectDir}/res")
-        }
-    }
+    testImplementation("io.kotest:kotest-runner-junit5")
 }
-
-// note: there are no unit tests in this module!
@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" inherit-compiler-output="true">
-    <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-      <excludeFolder url="file://$MODULE_DIR$/build" />
-    </content>
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
-    <orderEntry type="library" name="michael.bull.kotlin.result.jvm" level="project" />
-  </component>
-</module>
@@ -29,4 +29,23 @@ fun Path.sanitize(): Path {
    } catch (iox: IOException) {
        throw FileSystemException(this.toFile()).also { it.initCause(iox) }
    }
-}
+}
+
+
+object SymbolNames {
+    /**
+     * Strips Prog8 symbol prefixes (p8b_, p8t_, p8s_, p8v_, p8l_, p8c_) from a scoped name.
+     * Example: "p8b_plane.p8t_Point" -> "plane.Point"
+     * Used to compare names across different contexts where prefixes may or may not be applied.
+     * See https://github.com/irmen/prog8/issues/198
+     */
+    fun stripPrefixes(scopedName: String): String {
+        return scopedName.split('.')
+            .map { part ->
+                if(part.length > 4 && part.startsWith("p8") && part[2].isLetter() && part[3] == '_')
+                    part.drop(4)
+                else part
+            }
+            .joinToString(".")
+    }
+}
@@ -30,40 +30,48 @@ private val NumericDatatypes = arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE, Ba


 class FSignature(val pure: Boolean,      // does it have side effects?
-                 val returnType: BaseDataType?,
+                 val returnTypes: Array<BaseDataType>,
                 vararg val parameters: FParam) {

    fun callConvention(actualParamTypes: List<BaseDataType>): CallConvention {
-        val returns: ReturnConvention = when (returnType) {
-            BaseDataType.UBYTE, BaseDataType.BYTE -> ReturnConvention(returnType, RegisterOrPair.A)
-            BaseDataType.UWORD, BaseDataType.WORD -> ReturnConvention(returnType, RegisterOrPair.AY)
-            BaseDataType.LONG -> ReturnConvention(returnType, RegisterOrPair.R14R15_32)
-            BaseDataType.FLOAT -> ReturnConvention(returnType, RegisterOrPair.FAC1)
-            in IterableDatatypes -> ReturnConvention(returnType!!, RegisterOrPair.AY)
-            null -> ReturnConvention(null, null)
-            else -> {
-                // return type depends on arg type
-                when (val paramType = actualParamTypes.first()) {
-                    BaseDataType.UBYTE, BaseDataType.BYTE -> ReturnConvention(paramType, RegisterOrPair.A)
-                    BaseDataType.UWORD, BaseDataType.WORD -> ReturnConvention(paramType, RegisterOrPair.AY)
-                    BaseDataType.LONG -> ReturnConvention(returnType, RegisterOrPair.R14R15_32)
-                    BaseDataType.FLOAT -> ReturnConvention(paramType, RegisterOrPair.FAC1)
-                    in IterableDatatypes -> ReturnConvention(paramType, RegisterOrPair.AY)
-                    else -> ReturnConvention(paramType, null)
+        val returns: ReturnConvention
+        if(returnTypes.isEmpty())
+            returns = ReturnConvention(null, null)
+        else if(returnTypes.size==1) {
+            val returnType = returnTypes[0]
+            returns = when (returnType) {
+                BaseDataType.UBYTE, BaseDataType.BYTE -> ReturnConvention(returnType, RegisterOrPair.A)
+                BaseDataType.UWORD, BaseDataType.WORD -> ReturnConvention(returnType, RegisterOrPair.AY)
+                BaseDataType.LONG -> ReturnConvention(returnType, RegisterOrPair.R14R15)
+                BaseDataType.FLOAT -> ReturnConvention(returnType, RegisterOrPair.FAC1)
+                in IterableDatatypes -> ReturnConvention(returnType, RegisterOrPair.AY)
+                else -> {
+                    // return type depends on arg type
+                    when (val paramType = actualParamTypes.first()) {
+                        BaseDataType.UBYTE, BaseDataType.BYTE -> ReturnConvention(paramType, RegisterOrPair.A)
+                        BaseDataType.UWORD, BaseDataType.WORD -> ReturnConvention(paramType, RegisterOrPair.AY)
+                        BaseDataType.LONG -> ReturnConvention(returnType, RegisterOrPair.R14R15)
+                        BaseDataType.FLOAT -> ReturnConvention(paramType, RegisterOrPair.FAC1)
+                        in IterableDatatypes -> ReturnConvention(paramType, RegisterOrPair.AY)
+                        else -> ReturnConvention(paramType, null)
+                    }
                }
            }
+        } else {
+            // note: this path is currently never hit because the builtin functions with multiple return values have been handled in specialized optimized codegens already earlier.
+            TODO("multiple return types from builtin function")
        }

        return when {
            actualParamTypes.isEmpty() -> CallConvention(emptyList(), returns)
            actualParamTypes.size==1 -> {
-                // One parameter goes via register/registerpair.
+                // One parameter goes via register/registerpair (except longs)
                // this avoids repeated code for every caller to store the value in the subroutine's argument variable.
                // (that store is still done, but only coded once at the start at the subroutine itself rather than at every call site).
                val paramConv = when(val paramType = actualParamTypes[0]) {
                    BaseDataType.UBYTE, BaseDataType.BYTE -> ParamConvention(paramType, RegisterOrPair.A, false)
                    BaseDataType.UWORD, BaseDataType.WORD -> ParamConvention(paramType, RegisterOrPair.AY, false)
-                    BaseDataType.LONG -> ParamConvention(paramType, RegisterOrPair.R14R15_32, false)
+                    BaseDataType.LONG -> ParamConvention(paramType, null, true)
                    BaseDataType.FLOAT -> ParamConvention(paramType, RegisterOrPair.AY, false)      // NOTE: for builtin functions, floating point arguments are passed by reference (so you get a pointer in AY)
                    in IterableDatatypes -> ParamConvention(paramType, RegisterOrPair.AY, false)
                    else -> ParamConvention(paramType, null, false)
@@ -89,83 +97,102 @@ class FSignature(val pure: Boolean,      // does it have side effects?
 }

 val BuiltinFunctions: Map<String, FSignature> = mapOf(
-    "setlsb"  to FSignature(false, null, FParam("variable", BaseDataType.WORD, BaseDataType.UWORD), FParam("value", BaseDataType.BYTE, BaseDataType.UBYTE)),
-    "setmsb"  to FSignature(false, null, FParam("variable", BaseDataType.WORD, BaseDataType.UWORD), FParam("value", BaseDataType.BYTE, BaseDataType.UBYTE)),
-    "rol"     to FSignature(false, null, FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
-    "ror"     to FSignature(false, null, FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
-    "rol2"    to FSignature(false, null, FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
-    "ror2"    to FSignature(false, null, FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
-    "cmp"     to FSignature(false, null, FParam("value1", *IntegerDatatypes), FParam("value2", *NumericDatatypes)),  // cmp returns result in the cpu status flags, but not asa proper return value
-    "prog8_lib_stringcompare"     to FSignature(true, BaseDataType.BYTE, FParam("str1", BaseDataType.STR), FParam("str2", BaseDataType.STR)),
-    "prog8_lib_square_byte"       to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.BYTE, BaseDataType.UBYTE)),
-    "prog8_lib_square_word"       to FSignature(true, BaseDataType.UWORD, FParam("value", BaseDataType.WORD, BaseDataType.UWORD)),
-    "prog8_lib_structalloc"       to FSignature(true, BaseDataType.UWORD),
-    "abs"           to FSignature(true, null, FParam("value", *NumericDatatypes)),
-    "abs__byte"     to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.BYTE)),
-    "abs__word"     to FSignature(true, BaseDataType.UWORD, FParam("value", BaseDataType.WORD)),
-    "abs__long"     to FSignature(true, BaseDataType.LONG, FParam("value", BaseDataType.LONG)),
-    "abs__float"    to FSignature(true, BaseDataType.FLOAT, FParam("value", BaseDataType.FLOAT)),
-    "len"           to FSignature(true, BaseDataType.UWORD, FParam("values", *IterableDatatypes)),
-    "sizeof"        to FSignature(true, BaseDataType.UBYTE, FParam("object", *(BaseDataType.entries - BaseDataType.STRUCT_INSTANCE).toTypedArray())),
-    "offsetof"      to FSignature(true, BaseDataType.UBYTE, FParam("field", BaseDataType.UBYTE)),
-    "sgn"           to FSignature(true, BaseDataType.BYTE, FParam("value", *NumericDatatypes)),
-    "sqrt"          to FSignature(true, null, FParam("value", *NumericDatatypes)),
-    "sqrt__ubyte"   to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.UBYTE)),
-    "sqrt__uword"   to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.UWORD)),
-    "sqrt__long"    to FSignature(true, BaseDataType.UWORD, FParam("value", BaseDataType.LONG)),
-    "sqrt__float"   to FSignature(true, BaseDataType.FLOAT, FParam("value", BaseDataType.FLOAT)),
-    "divmod"        to FSignature(false, null, FParam("dividend", BaseDataType.UBYTE, BaseDataType.UWORD), FParam("divisor", BaseDataType.UBYTE, BaseDataType.UWORD), FParam("quotient", BaseDataType.UBYTE, BaseDataType.UWORD), FParam("remainder", BaseDataType.UBYTE, BaseDataType.UWORD)),
-    "divmod__ubyte" to FSignature(false, null, FParam("dividend", BaseDataType.UBYTE), FParam("divisor", BaseDataType.UBYTE), FParam("quotient", BaseDataType.UBYTE), FParam("remainder", BaseDataType.UBYTE)),
-    "divmod__uword" to FSignature(false, null, FParam("dividend", BaseDataType.UWORD), FParam("divisor", BaseDataType.UWORD), FParam("quotient", BaseDataType.UWORD), FParam("remainder", BaseDataType.UWORD)),
-    "lsb"           to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
-    "lsb__long"     to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.LONG)),
-    "msb"           to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
-    "msb__long"     to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.LONG)),
-    "lsw"           to FSignature(true, BaseDataType.UWORD, FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
-    "msw"           to FSignature(true, BaseDataType.UWORD, FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
-    "mkword"        to FSignature(true, BaseDataType.UWORD, FParam("msb", BaseDataType.UBYTE), FParam("lsb", BaseDataType.UBYTE)),
-    "mklong"        to FSignature(true, BaseDataType.LONG, FParam("msb", BaseDataType.UBYTE), FParam("b2", BaseDataType.UBYTE), FParam("b1", BaseDataType.UBYTE), FParam("lsb", BaseDataType.UBYTE)),
-    "mklong2"       to FSignature(true, BaseDataType.LONG, FParam("msw", BaseDataType.UWORD), FParam("lsw", BaseDataType.UWORD)),
-    "clamp"         to FSignature(true, null, FParam("value", BaseDataType.BYTE), FParam("minimum", BaseDataType.BYTE), FParam("maximum", BaseDataType.BYTE)),
-    "clamp__byte"   to FSignature(true, BaseDataType.BYTE, FParam("value", BaseDataType.BYTE), FParam("minimum", BaseDataType.BYTE), FParam("maximum", BaseDataType.BYTE)),
-    "clamp__ubyte"  to FSignature(true, BaseDataType.UBYTE, FParam("value", BaseDataType.UBYTE), FParam("minimum", BaseDataType.UBYTE), FParam("maximum", BaseDataType.UBYTE)),
-    "clamp__word"   to FSignature(true, BaseDataType.WORD, FParam("value", BaseDataType.WORD), FParam("minimum", BaseDataType.WORD), FParam("maximum", BaseDataType.WORD)),
-    "clamp__uword"  to FSignature(true, BaseDataType.UWORD, FParam("value", BaseDataType.UWORD), FParam("minimum", BaseDataType.UWORD), FParam("maximum", BaseDataType.UWORD)),
-    "clamp__long"   to FSignature(true, BaseDataType.LONG, FParam("value", BaseDataType.LONG), FParam("minimum", BaseDataType.LONG), FParam("maximum", BaseDataType.LONG)),
-    "min"           to FSignature(true, null, FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
-    "min__byte"     to FSignature(true, BaseDataType.BYTE, FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
-    "min__ubyte"    to FSignature(true, BaseDataType.UBYTE, FParam("val1", BaseDataType.UBYTE), FParam("val2", BaseDataType.UBYTE)),
-    "min__word"     to FSignature(true, BaseDataType.WORD, FParam("val1", BaseDataType.WORD), FParam("val2", BaseDataType.WORD)),
-    "min__uword"    to FSignature(true, BaseDataType.UWORD, FParam("val1", BaseDataType.UWORD), FParam("val2", BaseDataType.UWORD)),
-    "min__long"     to FSignature(true, BaseDataType.LONG, FParam("val1", BaseDataType.LONG), FParam("val2", BaseDataType.LONG)),
-    "max"           to FSignature(true, null, FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
-    "max__byte"     to FSignature(true, BaseDataType.BYTE, FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
-    "max__ubyte"    to FSignature(true, BaseDataType.UBYTE, FParam("val1", BaseDataType.UBYTE), FParam("val2", BaseDataType.UBYTE)),
-    "max__word"     to FSignature(true, BaseDataType.WORD, FParam("val1", BaseDataType.WORD), FParam("val2", BaseDataType.WORD)),
-    "max__uword"    to FSignature(true, BaseDataType.UWORD, FParam("val1", BaseDataType.UWORD), FParam("val2", BaseDataType.UWORD)),
-    "max__long"     to FSignature(true, BaseDataType.LONG, FParam("val1", BaseDataType.LONG), FParam("val2", BaseDataType.LONG)),
-    "peek"          to FSignature(true, BaseDataType.UBYTE, FParam("address", BaseDataType.UWORD)),
-    "peekbool"      to FSignature(true, BaseDataType.BOOL, FParam("address", BaseDataType.UWORD)),
-    "peekw"         to FSignature(true, BaseDataType.UWORD, FParam("address", BaseDataType.UWORD)),
-    "peekl"         to FSignature(true, BaseDataType.LONG, FParam("address", BaseDataType.UWORD)),
-    "peekf"         to FSignature(true, BaseDataType.FLOAT, FParam("address", BaseDataType.UWORD)),
-    "poke"          to FSignature(false, null, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.UBYTE, BaseDataType.BYTE)),
-    "pokebool"      to FSignature(false, null, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.BOOL)),
-    "pokebowl"      to FSignature(false, null, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.BOOL)),
-    "pokew"         to FSignature(false, null, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.UWORD, BaseDataType.WORD)),
-    "pokel"         to FSignature(false, null, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.LONG)),
-    "pokef"         to FSignature(false, null, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.FLOAT)),
-    "pokemon"       to FSignature(false, BaseDataType.UBYTE, FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.UBYTE)),
-    "rsave"         to FSignature(false, null),
-    "rrestore"      to FSignature(false, null),
-    "memory"        to FSignature(true, BaseDataType.UWORD, FParam("name", BaseDataType.STR), FParam("size", BaseDataType.UWORD), FParam("alignment", BaseDataType.UWORD)),
-    "callfar"       to FSignature(false, BaseDataType.UWORD, FParam("bank", BaseDataType.UBYTE), FParam("address", BaseDataType.UWORD), FParam("arg", BaseDataType.UWORD)),
-    "callfar2"      to FSignature(false, BaseDataType.UWORD, FParam("bank", BaseDataType.UBYTE), FParam("address", BaseDataType.UWORD), FParam("argA", BaseDataType.UBYTE), FParam("argX", BaseDataType.UBYTE), FParam("argY", BaseDataType.UBYTE), FParam("argC", BaseDataType.BOOL)),
-    "call"          to FSignature(false, BaseDataType.UWORD, FParam("address", BaseDataType.UWORD)),
+    "setlsb"  to FSignature(false, emptyArray(), FParam("variable", BaseDataType.WORD, BaseDataType.UWORD, BaseDataType.LONG), FParam("value", BaseDataType.BYTE, BaseDataType.UBYTE)),
+    "setmsb"  to FSignature(false, emptyArray(), FParam("variable", BaseDataType.WORD, BaseDataType.UWORD, BaseDataType.LONG), FParam("value", BaseDataType.BYTE, BaseDataType.UBYTE)),
+    "rol"     to FSignature(false, emptyArray(), FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
+    "ror"     to FSignature(false, emptyArray(), FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
+    "rol2"    to FSignature(false, emptyArray(), FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
+    "ror2"    to FSignature(false, emptyArray(), FParam("item", BaseDataType.UBYTE, BaseDataType.UWORD, BaseDataType.LONG)),
+    "cmp"     to FSignature(false, emptyArray(), FParam("value1", *IntegerDatatypes), FParam("value2", *NumericDatatypes)),  // cmp returns result in the cpu status flags, but not asa proper return value
+    "prog8_lib_stringcompare"     to FSignature(true, arrayOf(BaseDataType.BYTE), FParam("str1", BaseDataType.STR), FParam("str2", BaseDataType.STR)),
+    "prog8_lib_square_byte"       to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.BYTE, BaseDataType.UBYTE)),
+    "prog8_lib_square_word"       to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("value", BaseDataType.WORD, BaseDataType.UWORD)),
+    "prog8_lib_square_long"       to FSignature(true, arrayOf(BaseDataType.LONG), FParam("value", BaseDataType.LONG)),
+    "prog8_lib_structalloc"       to FSignature(true, arrayOf(BaseDataType.UWORD)),
+    "prog8_lib_copylong"          to FSignature(false, emptyArray(), FParam("pointer1", BaseDataType.UWORD), FParam("pointer2", BaseDataType.UWORD)),
+    "prog8_lib_copyfloat"         to FSignature(false, emptyArray(), FParam("pointer1", BaseDataType.UWORD), FParam("pointer2", BaseDataType.UWORD)),
+    "abs"           to FSignature(true, arrayOf(BaseDataType.UNDEFINED), FParam("value", *NumericDatatypes)),
+    "abs__byte"     to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.BYTE)),
+    "abs__word"     to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("value", BaseDataType.WORD)),
+    "abs__long"     to FSignature(true, arrayOf(BaseDataType.LONG), FParam("value", BaseDataType.LONG)),
+    "abs__float"    to FSignature(true, arrayOf(BaseDataType.FLOAT), FParam("value", BaseDataType.FLOAT)),
+    "len"           to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("values", *IterableDatatypes)),
+    "sizeof"        to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("object", *(BaseDataType.entries - BaseDataType.STRUCT_INSTANCE).toTypedArray())),
+    "offsetof"      to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("field", BaseDataType.UBYTE)),
+    "sgn"           to FSignature(true, arrayOf(BaseDataType.BYTE), FParam("value", *NumericDatatypes)),
+    "sqrt"          to FSignature(true, arrayOf(BaseDataType.UNDEFINED), FParam("value", *NumericDatatypes)),
+    "sqrt__ubyte"   to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.UBYTE)),
+    "sqrt__uword"   to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.UWORD)),
+    "sqrt__long"    to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("value", BaseDataType.LONG)),
+    "sqrt__float"   to FSignature(true, arrayOf(BaseDataType.FLOAT), FParam("value", BaseDataType.FLOAT)),
+    "divmod"        to FSignature(false, arrayOf(BaseDataType.UNDEFINED, BaseDataType.UNDEFINED), FParam("dividend", BaseDataType.UBYTE, BaseDataType.UWORD), FParam("divisor", BaseDataType.UBYTE, BaseDataType.UWORD)),
+    "divmod__ubyte" to FSignature(false, arrayOf(BaseDataType.UBYTE, BaseDataType.UBYTE), FParam("dividend", BaseDataType.UBYTE), FParam("divisor", BaseDataType.UBYTE)),
+    "divmod__uword" to FSignature(false, arrayOf(BaseDataType.UWORD, BaseDataType.UWORD), FParam("dividend", BaseDataType.UWORD), FParam("divisor", BaseDataType.UWORD)),
+    "divmod__byte"  to FSignature(false, arrayOf(BaseDataType.BYTE, BaseDataType.BYTE), FParam("dividend", BaseDataType.BYTE), FParam("divisor", BaseDataType.BYTE)),
+    "divmod__word"  to FSignature(false, arrayOf(BaseDataType.WORD, BaseDataType.WORD), FParam("dividend", BaseDataType.WORD), FParam("divisor", BaseDataType.WORD)),
+    "lmh"           to FSignature(true, arrayOf(BaseDataType.UBYTE, BaseDataType.UBYTE, BaseDataType.UBYTE), FParam("value", BaseDataType.LONG)),
+    "lsb"           to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
+    "lsb__long"     to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.LONG)),
+    "msb"           to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
+    "msb__long"     to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.LONG)),
+    "lsw"           to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
+    "msw"           to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)),
+    "mkword"        to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("msb", BaseDataType.UBYTE), FParam("lsb", BaseDataType.UBYTE)),
+    "mklong"        to FSignature(true, arrayOf(BaseDataType.LONG), FParam("msb", BaseDataType.UBYTE), FParam("b2", BaseDataType.UBYTE), FParam("b1", BaseDataType.UBYTE), FParam("lsb", BaseDataType.UBYTE)),
+    "mklong2"       to FSignature(true, arrayOf(BaseDataType.LONG), FParam("msw", BaseDataType.UWORD), FParam("lsw", BaseDataType.UWORD)),
+    "clamp"         to FSignature(true, arrayOf(BaseDataType.UNDEFINED), FParam("value", BaseDataType.BYTE), FParam("minimum", BaseDataType.BYTE), FParam("maximum", BaseDataType.BYTE)),
+    "clamp__byte"   to FSignature(true, arrayOf(BaseDataType.BYTE), FParam("value", BaseDataType.BYTE), FParam("minimum", BaseDataType.BYTE), FParam("maximum", BaseDataType.BYTE)),
+    "clamp__ubyte"  to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("value", BaseDataType.UBYTE), FParam("minimum", BaseDataType.UBYTE), FParam("maximum", BaseDataType.UBYTE)),
+    "clamp__word"   to FSignature(true, arrayOf(BaseDataType.WORD), FParam("value", BaseDataType.WORD), FParam("minimum", BaseDataType.WORD), FParam("maximum", BaseDataType.WORD)),
+    "clamp__uword"  to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("value", BaseDataType.UWORD), FParam("minimum", BaseDataType.UWORD), FParam("maximum", BaseDataType.UWORD)),
+    "clamp__long"   to FSignature(true, arrayOf(BaseDataType.LONG), FParam("value", BaseDataType.LONG), FParam("minimum", BaseDataType.LONG), FParam("maximum", BaseDataType.LONG)),
+    "min"           to FSignature(true, arrayOf(BaseDataType.UNDEFINED), FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
+    "min__byte"     to FSignature(true, arrayOf(BaseDataType.BYTE), FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
+    "min__ubyte"    to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("val1", BaseDataType.UBYTE), FParam("val2", BaseDataType.UBYTE)),
+    "min__word"     to FSignature(true, arrayOf(BaseDataType.WORD), FParam("val1", BaseDataType.WORD), FParam("val2", BaseDataType.WORD)),
+    "min__uword"    to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("val1", BaseDataType.UWORD), FParam("val2", BaseDataType.UWORD)),
+    "min__long"     to FSignature(true, arrayOf(BaseDataType.LONG), FParam("val1", BaseDataType.LONG), FParam("val2", BaseDataType.LONG)),
+    "max"           to FSignature(true, arrayOf(BaseDataType.UNDEFINED), FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
+    "max__byte"     to FSignature(true, arrayOf(BaseDataType.BYTE), FParam("val1", BaseDataType.BYTE), FParam("val2", BaseDataType.BYTE)),
+    "max__ubyte"    to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("val1", BaseDataType.UBYTE), FParam("val2", BaseDataType.UBYTE)),
+    "max__word"     to FSignature(true, arrayOf(BaseDataType.WORD), FParam("val1", BaseDataType.WORD), FParam("val2", BaseDataType.WORD)),
+    "max__uword"    to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("val1", BaseDataType.UWORD), FParam("val2", BaseDataType.UWORD)),
+    "max__long"     to FSignature(true, arrayOf(BaseDataType.LONG), FParam("val1", BaseDataType.LONG), FParam("val2", BaseDataType.LONG)),
+    "peek"          to FSignature(true, arrayOf(BaseDataType.UBYTE), FParam("address", BaseDataType.UWORD)),
+    "peekbool"      to FSignature(true, arrayOf(BaseDataType.BOOL), FParam("address", BaseDataType.UWORD)),
+    "peekw"         to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("address", BaseDataType.UWORD)),
+    "peekl"         to FSignature(true, arrayOf(BaseDataType.LONG), FParam("address", BaseDataType.UWORD)),
+    "peekf"         to FSignature(true, arrayOf(BaseDataType.FLOAT), FParam("address", BaseDataType.UWORD)),
+    "poke"          to FSignature(false, emptyArray(), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.UBYTE, BaseDataType.BYTE)),
+    "pokebool"      to FSignature(false, emptyArray(), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.BOOL)),
+    "pokebowl"      to FSignature(false, emptyArray(), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.BOOL)),
+    "pokew"         to FSignature(false, emptyArray(), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.UWORD, BaseDataType.WORD)),
+    "pokel"         to FSignature(false, emptyArray(), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.LONG)),
+    "pokef"         to FSignature(false, emptyArray(), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.FLOAT)),
+    "pokemon"       to FSignature(false, arrayOf(BaseDataType.UBYTE), FParam("address", BaseDataType.UWORD), FParam("value", BaseDataType.UBYTE)),
+    "rsave"         to FSignature(false, emptyArray()),
+    "rrestore"      to FSignature(false, emptyArray()),
+    "memory"        to FSignature(true,  arrayOf(BaseDataType.UWORD), FParam("name", BaseDataType.STR), FParam("size", BaseDataType.UWORD), FParam("alignment", BaseDataType.UWORD)),
+    "memory__ref"   to FSignature(true, arrayOf(BaseDataType.UWORD), FParam("name", BaseDataType.STR)),
+    "callfar"       to FSignature(false, arrayOf(BaseDataType.UWORD), FParam("bank", BaseDataType.UBYTE), FParam("address", BaseDataType.UWORD), FParam("arg", BaseDataType.UWORD)),
+    "callfar2"      to FSignature(false, arrayOf(BaseDataType.UWORD), FParam("bank", BaseDataType.UBYTE), FParam("address", BaseDataType.UWORD), FParam("argA", BaseDataType.UBYTE), FParam("argX", BaseDataType.UBYTE), FParam("argY", BaseDataType.UBYTE), FParam("argC", BaseDataType.BOOL)),
+    "call"          to FSignature(false, arrayOf(BaseDataType.UWORD), FParam("address", BaseDataType.UWORD)),
+    "push"          to FSignature(false, emptyArray(), FParam("value", BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.BOOL)),
+    "pushw"         to FSignature(false, emptyArray(), FParam("value", BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.POINTER)),
+    "pushl"         to FSignature(false, emptyArray(), FParam("value", BaseDataType.LONG)),
+    "pushf"         to FSignature(false, emptyArray(), FParam("value", BaseDataType.FLOAT)),
+    "pop"           to FSignature(false, arrayOf(BaseDataType.UBYTE)),
+    "popw"          to FSignature(false, arrayOf(BaseDataType.UWORD)),
+    "popl"          to FSignature(false, arrayOf(BaseDataType.LONG)),
+    "popf"          to FSignature(false, arrayOf(BaseDataType.FLOAT)),
 )

 val InplaceModifyingBuiltinFunctions = setOf(
    "setlsb", "setmsb",
-    "rol", "ror", "rol2", "ror2",
-    "divmod", "divmod__ubyte", "divmod__uword"
+    "rol", "ror", "rol2", "ror2"
 )
+
+val SimpleBuiltinFunctions = setOf(
+    "msb", "lsb", "msw", "lsw",
+    "mkword", "mklong", "mklong2",
+    "set_carry", "set_irqd", "clear_carry", "clear_irqd")
@@ -18,13 +18,13 @@ class CompilationOptions(val output: OutputType,
                         var loadAddress: UInt,
                         var memtopAddress: UInt,
                         var warnSymbolShadowing: Boolean = false,
+                         var warnImplicitTypeCast: Boolean = false,
                         var optimize: Boolean = false,
                         var asmQuiet: Boolean = false,
                         var asmListfile: Boolean = false,
                         var includeSourcelines: Boolean = false,
                         var dumpVariables: Boolean = false,
                         var dumpSymbols: Boolean = false,
-                         var experimentalCodegen: Boolean = false,
                         var varsHighBank: Int? = null,
                         var varsGolden: Boolean = false,
                         var slabsHighBank: Int? = null,
@@ -33,6 +33,7 @@ class CompilationOptions(val output: OutputType,
                         var ignoreFootguns: Boolean = false,
                         var outputDir: Path = Path(""),
                         var quiet: Boolean = false,
+                         var profilingInstrumentation: Boolean = false,
                         var symbolDefs: Map<String, String> = emptyMap()
 ) {
    init {
@@ -41,5 +42,79 @@ class CompilationOptions(val output: OutputType,

    companion object {
        val AllZeropageAllowed: List<UIntRange> = listOf(0u..255u)
+
+        fun builder(compTarget: ICompilationTarget) = Builder(compTarget)
+
+        class Builder(private val compTarget: ICompilationTarget) {
+            private var output: OutputType = compTarget.defaultOutputType
+            private var launcher: CbmPrgLauncherType = CbmPrgLauncherType.NONE
+            private var zeropage: ZeropageType = ZeropageType.DONTUSE
+            private var zpReserved: List<UIntRange> = emptyList()
+            private var zpAllowed: List<UIntRange> = AllZeropageAllowed
+            private var floats: Boolean = false
+            private var noSysInit: Boolean = false
+            private var romable: Boolean = false
+            private var compilerVersion: String = "unknown"
+            private var loadAddress: UInt = compTarget.PROGRAM_LOAD_ADDRESS
+            private var memtopAddress: UInt = compTarget.PROGRAM_MEMTOP_ADDRESS
+            private var warnSymbolShadowing: Boolean = false
+            private var warnImplicitTypeCast: Boolean = false
+            private var optimize: Boolean = false
+            private var asmQuiet: Boolean = false
+            private var asmListfile: Boolean = false
+            private var includeSourcelines: Boolean = false
+            private var dumpVariables: Boolean = false
+            private var dumpSymbols: Boolean = false
+            private var varsHighBank: Int? = null
+            private var varsGolden: Boolean = false
+            private var slabsHighBank: Int? = null
+            private var slabsGolden: Boolean = false
+            private var breakpointCpuInstruction: String? = null
+            private var ignoreFootguns: Boolean = false
+            private var outputDir: Path = Path("")
+            private var quiet: Boolean = false
+            private var profilingInstrumentation: Boolean = false
+            private var symbolDefs: Map<String, String> = emptyMap()
+
+            fun output(output: OutputType) = apply { this.output = output }
+            fun launcher(launcher: CbmPrgLauncherType) = apply { this.launcher = launcher }
+            fun zeropage(zeropage: ZeropageType) = apply { this.zeropage = zeropage }
+            fun zpReserved(zpReserved: List<UIntRange>) = apply { this.zpReserved = zpReserved }
+            fun zpAllowed(zpAllowed: List<UIntRange>) = apply { this.zpAllowed = zpAllowed }
+            fun floats(floats: Boolean) = apply { this.floats = floats }
+            fun noSysInit(noSysInit: Boolean) = apply { this.noSysInit = noSysInit }
+            fun romable(romable: Boolean) = apply { this.romable = romable }
+            fun compilerVersion(compilerVersion: String) = apply { this.compilerVersion = compilerVersion }
+            fun loadAddress(loadAddress: UInt) = apply { this.loadAddress = loadAddress }
+            fun memtopAddress(memtopAddress: UInt) = apply { this.memtopAddress = memtopAddress }
+            fun warnSymbolShadowing(warnSymbolShadowing: Boolean) = apply { this.warnSymbolShadowing = warnSymbolShadowing }
+            fun warnImplicitTypeCast(warnImplicitTypeCast: Boolean) = apply { this.warnImplicitTypeCast = warnImplicitTypeCast }
+            fun optimize(optimize: Boolean) = apply { this.optimize = optimize }
+            fun asmQuiet(asmQuiet: Boolean) = apply { this.asmQuiet = asmQuiet }
+            fun asmListfile(asmListfile: Boolean) = apply { this.asmListfile = asmListfile }
+            fun includeSourcelines(includeSourcelines: Boolean) = apply { this.includeSourcelines = includeSourcelines }
+            fun dumpVariables(dumpVariables: Boolean) = apply { this.dumpVariables = dumpVariables }
+            fun dumpSymbols(dumpSymbols: Boolean) = apply { this.dumpSymbols = dumpSymbols }
+            fun varsHighBank(varsHighBank: Int?) = apply { this.varsHighBank = varsHighBank }
+            fun varsGolden(varsGolden: Boolean) = apply { this.varsGolden = varsGolden }
+            fun slabsHighBank(slabsHighBank: Int?) = apply { this.slabsHighBank = slabsHighBank }
+            fun slabsGolden(slabsGolden: Boolean) = apply { this.slabsGolden = slabsGolden }
+            fun breakpointCpuInstruction(breakpointCpuInstruction: String?) = apply { this.breakpointCpuInstruction = breakpointCpuInstruction }
+            fun ignoreFootguns(ignoreFootguns: Boolean) = apply { this.ignoreFootguns = ignoreFootguns }
+            fun outputDir(outputDir: Path) = apply { this.outputDir = outputDir }
+            fun quiet(quiet: Boolean) = apply { this.quiet = quiet }
+            fun profilingInstrumentation(profilingInstrumentation: Boolean) = apply { this.profilingInstrumentation = profilingInstrumentation }
+            fun symbolDefs(symbolDefs: Map<String, String>) = apply { this.symbolDefs = symbolDefs }
+
+            fun build(): CompilationOptions {
+                return CompilationOptions(
+                    output, launcher, zeropage, zpReserved, zpAllowed, floats, noSysInit, romable, compTarget, compilerVersion,
+                    loadAddress, memtopAddress, warnSymbolShadowing, warnImplicitTypeCast, optimize, asmQuiet, asmListfile,
+                    includeSourcelines, dumpVariables, dumpSymbols, varsHighBank, varsGolden,
+                    slabsHighBank, slabsGolden, breakpointCpuInstruction, ignoreFootguns, outputDir, quiet,
+                    profilingInstrumentation, symbolDefs
+                )
+            }
+        }
    }
 }
@@ -14,8 +14,11 @@ fun Number.toHex(): String {
    //  larger -> "$12345678"
    // negative values are prefixed with '-'.
    val integer = this.toLong()
-    if(integer<0)
+    if(integer<0) {
+        if(integer==-2147483648L)
+            return "$80000000"      // the exception to the rule, because -$80000000 is not a valid hex number
        return '-' + abs(integer).toHex()
+    }
    return when (integer) {
        in 0 until 16 -> integer.toString()
        in 0 until 0x100 -> "$"+integer.toString(16).padStart(2,'0')
@@ -95,3 +98,24 @@ fun String.unescape(): String {
    }
    return result.joinToString("")
 }
+
+// === Symbol name prefixing ===
+// These are used by code generators to add p8b_/p8s_/p8v_/etc. prefixes to symbol names.
+// The prefix character depends on the symbol type (block='b', sub='s', variable='v', etc.)
+// Scoped names (containing dots) have each part prefixed according to its role.
+
+fun prefixScopedName(name: String, type: Char): String {
+    val generatedPrefix = "p8_label_gen_"
+    if('.' !in name) {
+        if(name.startsWith(generatedPrefix))
+            return name
+        return "p8${type}_$name"
+    }
+    val parts = name.split('.')
+    val firstPrefixed = "p8b_${parts[0]}"
+    val lastPart = parts.last()
+    val lastPrefixed = if(lastPart.startsWith(generatedPrefix)) lastPart else "p8${type}_$lastPart"
+    val inbetweenPrefixed = parts.drop(1).dropLast(1).map{ "p8s_$it" }
+    val prefixed = listOf(firstPrefixed) + inbetweenPrefixed + listOf(lastPrefixed)
+    return prefixed.joinToString(".")
+}
@@ -0,0 +1,444 @@
+package prog8.code.core
+
+import java.util.*
+
+
+/**
+ * Base data types supported by the Prog8 compiler.
+ * These represent the fundamental types that can be used in Prog8 programs.
+ */
+enum class BaseDataType {
+    UBYTE,              // pass by value            8 bits unsigned
+    BYTE,               // pass by value            8 bits signed
+    UWORD,              // pass by value            16 bits unsigned
+    WORD,               // pass by value            16 bits signed
+    LONG,               // pass by value            32 bits signed
+    FLOAT,              // pass by value            machine dependent
+    BOOL,               // pass by value            bit 0 of an 8-bit byte
+    STR,                // pass by reference
+    ARRAY,              // pass by reference, subtype is the element type
+    ARRAY_SPLITW,       // pass by reference, split word layout, subtype is the element type (restricted to word types)
+    POINTER,            // typed pointer, subtype is whatever type is pointed to
+    STRUCT_INSTANCE,    // the actual instance of a struct (not directly supported in the language yet, but we need its type)
+    ARRAY_POINTER,      // array of pointers (uwords), subtype is whatever type each element points to
+    UNDEFINED;
+
+
+    fun largerSizeThan(other: BaseDataType) =
+        when {
+            this == other -> false
+            this.isByteOrBool -> false
+            this.isWord -> other.isByteOrBool
+            this == LONG -> other.isByteOrBool || other.isWord
+            this == STR && other == UWORD || this == UWORD && other == STR -> false
+            this.isArray && other.isArray -> false
+            this.isArray -> other.isByteOrBool
+            this == STR -> other.isByteOrBool
+            this.isPointer -> other.isByteOrBool
+            else -> true
+        }
+
+    fun equalsSize(other: BaseDataType) =
+        when {
+            this == other -> true
+            this.isArray && other.isArray -> true
+            this.isByteOrBool -> other.isByteOrBool
+            this.isWord -> other.isWord || other.isPointer
+            this.isPointer -> other.isWord
+            this == STR && other== UWORD || this== UWORD && other== STR -> true
+            this == STR && other.isArray -> true
+            this.isArray && other == STR -> true
+            else -> false
+        }
+}
+
+
+// ============================================================================
+// BaseDataType Extension Properties
+// ============================================================================
+
+val BaseDataType.isByte get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE)
+val BaseDataType.isUnsignedByte get() = this == BaseDataType.UBYTE
+val BaseDataType.isSignedByte get() = this == BaseDataType.BYTE
+val BaseDataType.isBool get() = this == BaseDataType.BOOL
+val BaseDataType.isByteOrBool get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.BOOL)
+val BaseDataType.isWord get() = this in arrayOf(BaseDataType.UWORD, BaseDataType.WORD)
+val BaseDataType.isUnsignedWord get() = this == BaseDataType.UWORD
+val BaseDataType.isSignedWord get() = this == BaseDataType.WORD
+val BaseDataType.isLong get() = this == BaseDataType.LONG
+val BaseDataType.isFloat get() = this == BaseDataType.FLOAT
+val BaseDataType.isInteger get() = this in setOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)
+val BaseDataType.isIntegerOrBool get() = this in setOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG, BaseDataType.BOOL)
+val BaseDataType.isWordOrByteOrBool get() = this in setOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.BOOL)
+val BaseDataType.isNumeric get() = this == BaseDataType.FLOAT || this.isInteger
+val BaseDataType.isNumericOrBool get() = this == BaseDataType.BOOL || this.isNumeric
+val BaseDataType.isSigned get() = this in setOf(BaseDataType.BYTE, BaseDataType.WORD, BaseDataType.LONG, BaseDataType.FLOAT)
+val BaseDataType.isUnsigned get() = !this.isSigned
+val BaseDataType.isSignedInteger get() = this.isSigned && this.isInteger
+val BaseDataType.isUnsignedInteger get() = this.isUnsigned && this.isInteger
+val BaseDataType.isArray get() = this == BaseDataType.ARRAY || this == BaseDataType.ARRAY_SPLITW || this == BaseDataType.ARRAY_POINTER
+val BaseDataType.isPointer get() = this == BaseDataType.POINTER
+val BaseDataType.isStructInstance get() = this == BaseDataType.STRUCT_INSTANCE
+val BaseDataType.isPointerArray get() = this == BaseDataType.ARRAY_POINTER
+val BaseDataType.isSplitWordArray get() = this == BaseDataType.ARRAY_SPLITW || this == BaseDataType.ARRAY_POINTER       // pointer arrays are also always stored as split uwords
+val BaseDataType.isIterable get() =  this in setOf(BaseDataType.STR, BaseDataType.ARRAY, BaseDataType.ARRAY_SPLITW, BaseDataType.ARRAY_POINTER)
+val BaseDataType.isPassByRef get() = this.isIterable && !this.isPointer
+val BaseDataType.isPassByValue get() = !this.isIterable || this.isPointer
+
+
+/**
+ * Interface for types that can be used as subtypes in DataType.
+ * Primarily used for struct types.
+ */
+interface ISubType {
+    val scopedNameString: String
+    fun memsize(sizer: IMemSizer): Int
+    fun sameas(other: ISubType): Boolean
+    fun getFieldType(name: String): DataType?
+}
+
+
+/**
+ * Represents a complete data type in Prog8, including base type and optional subtype.
+ * 
+ * DataType is immutable after construction. Use the companion object factory methods
+ * to create instances.
+ * 
+ * @property base The base data type (e.g., UBYTE, WORD, ARRAY, POINTER)
+ * @property sub The subtype for arrays and strings (e.g., UBYTE for byte arrays)
+ * @property subType The structured subtype for pointers and struct instances
+ * @property subTypeFromAntlr Deferred subtype resolution from parser
+ */
+class DataType private constructor(
+    val base: BaseDataType,
+    val sub: BaseDataType?,
+    var subType: ISubType?,
+    var subTypeFromAntlr: List<String>? = null
+) {
+
+    init {
+        when {
+            base.isPointerArray -> {
+                require(sub!=null || subType!=null || subTypeFromAntlr!=null)
+            }
+            base.isArray -> {
+                require(sub != null && subType==null && subTypeFromAntlr==null)
+                if(base.isSplitWordArray)
+                    require(sub == BaseDataType.UWORD || sub == BaseDataType.WORD)
+            }
+            base==BaseDataType.STR -> require(sub==BaseDataType.UBYTE) { "string subtype should be ubyte" }
+            base!=BaseDataType.POINTER -> require(sub == null) { "only string, array and pointer base types can have a subtype"}
+            else -> {
+                require(sub == null || (subType == null && subTypeFromAntlr == null)) {
+                    "sub and subtype can't both be set"
+                }
+            }
+        }
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other !is DataType) return false
+        return base == other.base && sub == other.sub && (subType==other.subType || subType!!.sameas(other.subType!!))
+    }
+
+    override fun hashCode(): Int = Objects.hash(base, sub, subType)
+
+    fun setActualSubType(actualSubType: ISubType) {
+        subType = actualSubType
+        subTypeFromAntlr = null
+    }
+
+    // ============================================================================
+    // Companion Object - Factory Methods
+    // ============================================================================
+    
+    companion object {
+
+        val UBYTE = DataType(BaseDataType.UBYTE, null, null)
+        val BYTE = DataType(BaseDataType.BYTE, null, null)
+        val UWORD = DataType(BaseDataType.UWORD, null, null)
+        val WORD = DataType(BaseDataType.WORD, null, null)
+        val LONG = DataType(BaseDataType.LONG, null, null)
+        val FLOAT = DataType(BaseDataType.FLOAT, null, null)
+        val BOOL = DataType(BaseDataType.BOOL, null, null)
+        val STR = DataType(BaseDataType.STR, BaseDataType.UBYTE, null)
+        val UNDEFINED = DataType(BaseDataType.UNDEFINED, null, null)
+
+        private val simpletypes = mapOf(
+            BaseDataType.UBYTE to DataType(BaseDataType.UBYTE, null, null),
+            BaseDataType.BYTE to DataType(BaseDataType.BYTE, null, null),
+            BaseDataType.UWORD to DataType(BaseDataType.UWORD, null, null),
+            BaseDataType.WORD to DataType(BaseDataType.WORD, null, null),
+            BaseDataType.LONG to DataType(BaseDataType.LONG, null, null),
+            BaseDataType.FLOAT to DataType(BaseDataType.FLOAT, null, null),
+            BaseDataType.BOOL to DataType(BaseDataType.BOOL, null, null),
+            BaseDataType.STR to DataType(BaseDataType.STR, BaseDataType.UBYTE, null),
+            BaseDataType.UNDEFINED to DataType(BaseDataType.UNDEFINED, null, null)
+        )
+
+        fun forDt(dt: BaseDataType): DataType {
+            if(dt.isStructInstance)
+                TODO("cannot use struct instance as a data type (yet) - use a pointer instead")
+            return simpletypes.getValue(dt)
+        }
+
+        fun arrayFor(elementDt: BaseDataType, splitwordarray: Boolean=true): DataType {
+            require(!elementDt.isPointer) { "use other array constructor for arrays of pointers" }
+            val actualElementDt = if(elementDt==BaseDataType.STR) BaseDataType.UWORD else elementDt      // array of strings is actually just an array of UWORD pointers
+            return if(splitwordarray && actualElementDt.isWord)
+                DataType(BaseDataType.ARRAY_SPLITW, actualElementDt, null)
+            else {
+                if(actualElementDt.isNumericOrBool)
+                    DataType(BaseDataType.ARRAY, actualElementDt, null)
+                else
+                    throw NoSuchElementException("invalid basic element dt $elementDt")
+            }
+        }
+
+        fun arrayOfPointersTo(sub: BaseDataType): DataType = DataType(BaseDataType.ARRAY_POINTER, sub, null)
+        fun arrayOfPointersTo(structType: ISubType?): DataType = DataType(BaseDataType.ARRAY_POINTER, null, structType)
+        fun arrayOfPointersFromAntlrTo(sub: BaseDataType?, identifier: List<String>?): DataType =
+            DataType(BaseDataType.ARRAY_POINTER, sub, null, identifier)
+
+        fun pointer(base: BaseDataType): DataType = DataType(BaseDataType.POINTER, base, null)
+        fun pointer(dt: DataType): DataType = if(dt.isBasic)
+                DataType(BaseDataType.POINTER, dt.base, null)
+            else
+                DataType(BaseDataType.POINTER, null, dt.subType, dt.subTypeFromAntlr)
+        fun pointer(structType: ISubType): DataType = DataType(BaseDataType.POINTER, null, structType)
+        fun pointerFromAntlr(identifier: List<String>): DataType = DataType(BaseDataType.POINTER, null, null, identifier)
+        fun structInstance(type: ISubType?): DataType = DataType(BaseDataType.STRUCT_INSTANCE, sub=null, type)
+        fun structInstanceFromAntlr(struct: List<String>): DataType = DataType(BaseDataType.STRUCT_INSTANCE, null, null, subTypeFromAntlr = struct)
+    }
+
+
+    // ============================================================================
+    // DataType Methods
+    // ============================================================================
+
+    fun elementToArray(splitwords: Boolean = true): DataType {
+        return if (base == BaseDataType.UWORD || base == BaseDataType.WORD || base == BaseDataType.STR) arrayFor(base, splitwords)
+        else arrayFor(base, false)
+    }
+
+    fun elementType(): DataType =
+        when {
+            isPointerArray -> DataType(BaseDataType.POINTER, sub, subType)
+            base.isArray || base==BaseDataType.STR -> forDt(sub!!)
+            else -> throw IllegalArgumentException("not an array")
+        }
+
+    fun typeForAddressOf(msb: Boolean): DataType {
+        if (isUndefined)
+            return if(msb) pointer(BaseDataType.UBYTE) else UWORD
+        else {
+            if (isBasic)
+                return pointer(base)
+            if (isString)
+                return pointer(BaseDataType.UBYTE)
+            if (isPointer)
+                return UWORD
+            if (isArray) {
+                if (msb || isSplitWordArray)
+                    return pointer(BaseDataType.UBYTE)
+                val elementDt = elementType()
+                require(elementDt.isBasic)
+                return pointer(elementDt)
+            }
+            if (subType != null)
+                return pointer(this)
+            return UWORD
+        }
+    }
+
+    fun dereference(): DataType {
+        require(isPointer || isUnsignedWord) { "cannot dereference non-pointer type ${this}"}
+        return when {
+            isUnsignedWord -> forDt(BaseDataType.UBYTE)
+            sub!=null -> forDt(sub)
+            subType!=null -> DataType(BaseDataType.STRUCT_INSTANCE, null, subType)
+            subTypeFromAntlr!=null -> DataType(BaseDataType.STRUCT_INSTANCE, null, null, subTypeFromAntlr)
+            else -> throw IllegalArgumentException("cannot dereference this pointer type")
+        }
+    }
+
+    override fun toString(): String = when(base) {
+        BaseDataType.ARRAY -> {
+            when(sub) {
+                BaseDataType.BOOL -> "bool[]"
+                BaseDataType.FLOAT -> "float[]"
+                BaseDataType.BYTE -> "byte[]"
+                BaseDataType.WORD -> "word[]"
+                BaseDataType.UBYTE -> "ubyte[]"
+                BaseDataType.UWORD -> "uword[]"
+                BaseDataType.LONG -> "long[]"
+                else -> throw IllegalArgumentException("invalid sub type")
+            }
+        }
+        BaseDataType.ARRAY_SPLITW -> {
+            when(sub) {
+                BaseDataType.WORD -> "word[] (split)"
+                BaseDataType.UWORD -> "uword[] (split)"
+                else -> throw IllegalArgumentException("invalid sub type")
+            }
+        }
+        BaseDataType.POINTER -> {
+            if(sub!=null) "^^${sub.name.lowercase()}" else if(subType!=null) "^^${subType!!.scopedNameString}" else "^^${subTypeFromAntlr}"
+        }
+        BaseDataType.ARRAY_POINTER -> {
+            if(sub!=null) "^^${sub.name.lowercase()}[] (split)" else if (subType!=null) "^^${subType!!.scopedNameString}[] (split)" else "^^${subTypeFromAntlr}[] (split)"
+        }
+        BaseDataType.STRUCT_INSTANCE -> {
+            sub?.name?.lowercase() ?: if (subType!=null) subType!!.scopedNameString else "$subTypeFromAntlr"
+        }
+        else -> base.name.lowercase()
+    }
+
+    fun sourceString(): String = when (base) {
+        BaseDataType.BOOL -> "bool"
+        BaseDataType.UBYTE -> "ubyte"
+        BaseDataType.BYTE -> "byte"
+        BaseDataType.UWORD -> "uword"
+        BaseDataType.WORD -> "word"
+        BaseDataType.LONG -> "long"
+        BaseDataType.FLOAT -> "float"
+        BaseDataType.STR -> "str"
+        BaseDataType.POINTER -> {
+            when {
+                sub!=null -> "^^${sub.name.lowercase()}"
+                subType!=null -> "^^${subType!!.scopedNameString}"
+                subTypeFromAntlr!=null -> "^^${subTypeFromAntlr!!.joinToString(".")}"
+                else -> "?????"
+            }
+        }
+        BaseDataType.STRUCT_INSTANCE -> {
+            when {
+                sub!=null -> sub.name.lowercase()
+                subType!=null -> subType!!.scopedNameString
+                subTypeFromAntlr!=null -> subTypeFromAntlr!!.joinToString(".")
+                else -> "?????"
+            }
+        }
+        BaseDataType.ARRAY_POINTER -> {
+            when {
+                sub!=null -> "^^${sub.name.lowercase()}["
+                subType!=null -> "^^${subType!!.scopedNameString}["
+                subTypeFromAntlr!=null -> "^^${subTypeFromAntlr!!.joinToString(".")}["
+                else -> "????? ["
+            }
+        }
+        BaseDataType.ARRAY -> {
+            when(sub) {
+                BaseDataType.UBYTE -> "ubyte["
+                BaseDataType.UWORD -> "@nosplit uword["
+                BaseDataType.BOOL -> "bool["
+                BaseDataType.BYTE -> "byte["
+                BaseDataType.WORD -> "@nosplit word["
+                BaseDataType.LONG -> "long["
+                BaseDataType.FLOAT -> "float["
+                else -> throw IllegalArgumentException("invalid sub type")
+            }
+        }
+        BaseDataType.ARRAY_SPLITW -> {
+            when(sub) {
+                BaseDataType.UWORD -> "uword["
+                BaseDataType.WORD -> "word["
+                else -> throw IllegalArgumentException("invalid sub type")
+            }
+        }
+        BaseDataType.UNDEFINED -> throw IllegalArgumentException("wrong dt")
+    }
+
+    /**
+     * Check if this type is assignable to the given target type (perhaps via a typecast)
+     * without loss of precision.
+     */
+    infix fun isAssignableTo(targetType: DataType) =
+        when(base) {
+            BaseDataType.BOOL -> targetType.base == BaseDataType.BOOL
+            BaseDataType.UBYTE -> targetType.base in setOf(BaseDataType.UBYTE, BaseDataType.WORD, BaseDataType.UWORD, BaseDataType.LONG, BaseDataType.FLOAT)
+            BaseDataType.BYTE -> targetType.base in setOf(BaseDataType.BYTE, BaseDataType.WORD, BaseDataType.LONG, BaseDataType.FLOAT)
+            BaseDataType.UWORD -> targetType.base in setOf(BaseDataType.UWORD, BaseDataType.LONG, BaseDataType.FLOAT, BaseDataType.POINTER, BaseDataType.ARRAY_POINTER)
+            BaseDataType.WORD -> targetType.base in setOf(BaseDataType.WORD, BaseDataType.LONG, BaseDataType.FLOAT)
+            BaseDataType.LONG -> targetType.base in setOf(BaseDataType.LONG, BaseDataType.FLOAT)
+            BaseDataType.FLOAT -> targetType.base in arrayOf(BaseDataType.FLOAT)
+            BaseDataType.STR -> targetType.base in setOf(BaseDataType.STR, BaseDataType.UWORD) || (targetType.isPointer && targetType.sub==BaseDataType.UBYTE)
+            BaseDataType.ARRAY, BaseDataType.ARRAY_SPLITW -> targetType.base in setOf(BaseDataType.ARRAY, BaseDataType.ARRAY_SPLITW) && targetType.sub == sub
+            BaseDataType.POINTER -> {
+                when {
+                    targetType.base == BaseDataType.UWORD || targetType.base == BaseDataType.LONG -> true
+                    targetType.isPointer -> this.isUnsignedWord || this == targetType
+                    else -> false
+                }
+            }
+            BaseDataType.STRUCT_INSTANCE -> false        // we cannot deal with actual struct instances yet in any shape or form (only getting fields from it)
+            BaseDataType.ARRAY_POINTER -> false
+            BaseDataType.UNDEFINED -> false
+        }
+
+    fun largerSizeThan(other: DataType): Boolean = base.largerSizeThan(other.base)
+    fun equalsSize(other: DataType): Boolean = base.equalsSize(other.base)
+
+    /**
+     * Returns the memory size in bytes.
+     * Note: for pointer types, size() doesn't return the size of the pointer itself
+     * but the size of the thing it points to.
+     */
+    fun size(memsizer: IMemSizer): Int = if(sub!=null) {
+            memsizer.memorySize(sub)
+        } else if(subType!=null) {
+            subType!!.memsize(memsizer)
+        } else {
+            memsizer.memorySize(base)
+        }
+
+    // ============================================================================
+    // DataType Properties
+    // ============================================================================
+
+    val isBasic = sub==null && subType==null && subTypeFromAntlr==null
+    val isUndefined = base == BaseDataType.UNDEFINED
+    val isByte = base.isByte
+    val isUnsignedByte = base == BaseDataType.UBYTE
+    val isSignedByte = base == BaseDataType.BYTE
+    val isByteOrBool = base.isByteOrBool
+    val isWord = base.isWord
+    val isUnsignedWord =  base == BaseDataType.UWORD
+    val isSignedWord =  base == BaseDataType.WORD
+    val isInteger = base.isInteger
+    val isWordOrByteOrBool = base.isWordOrByteOrBool
+    val isIntegerOrBool = base.isIntegerOrBool
+    val isNumeric = base.isNumeric
+    val isNumericOrBool = base.isNumericOrBool
+    val isSigned = base.isSigned
+    val isUnsigned = !base.isSigned
+    val isSignedInteger = isSigned && isInteger
+    val isUnsignedInteger = isUnsigned && isInteger
+    val isArray = base.isArray
+    val isPointer = base.isPointer
+    val isPointerToByte = base.isPointer && sub?.isByteOrBool==true
+    val isPointerToWord = base.isPointer && sub?.isWord==true
+    val isStructInstance = base.isStructInstance
+    val isPointerArray = base.isPointerArray
+    val isBoolArray = base.isArray && !base.isPointerArray && sub == BaseDataType.BOOL
+    val isByteArray = base.isArray && !base.isPointerArray && (sub == BaseDataType.UBYTE || sub == BaseDataType.BYTE)
+    val isUnsignedByteArray = base.isArray && !base.isPointerArray && sub == BaseDataType.UBYTE
+    val isSignedByteArray = base.isArray && !base.isPointerArray && sub == BaseDataType.BYTE
+    val isWordArray = base.isArray && !base.isPointerArray && (sub == BaseDataType.UWORD || sub == BaseDataType.WORD)
+    val isUnsignedWordArray = base.isArray && !base.isPointerArray && sub == BaseDataType.UWORD
+    val isSignedWordArray = base.isArray && !base.isPointerArray && sub == BaseDataType.WORD
+    val isLongArray = base.isArray && sub == BaseDataType.LONG
+    val isFloatArray = base.isArray && !base.isPointerArray && sub == BaseDataType.FLOAT
+    val isString = base == BaseDataType.STR
+    val isBool = base == BaseDataType.BOOL
+    val isFloat = base == BaseDataType.FLOAT
+    val isLong = base == BaseDataType.LONG
+    val isStringly = base == BaseDataType.STR || base == BaseDataType.UWORD || (base == BaseDataType.ARRAY && (sub == BaseDataType.UBYTE || sub == BaseDataType.BYTE))
+    val isSplitWordArray = base.isSplitWordArray
+    val isSplitUnsignedWordArray = base.isSplitWordArray && !base.isPointerArray && sub == BaseDataType.UWORD
+    val isSplitSignedWordArray = base.isSplitWordArray && !base.isPointerArray && sub == BaseDataType.WORD
+    val isIterable =  base.isIterable
+    val isPassByRef = base.isPassByRef
+    val isPassByValue = base.isPassByValue
+}
@@ -1,387 +1,5 @@
 package prog8.code.core

-import java.util.*
-
-enum class BaseDataType {
-    UBYTE,              // pass by value            8 bits unsigned
-    BYTE,               // pass by value            8 bits signed
-    UWORD,              // pass by value            16 bits unsigned
-    WORD,               // pass by value            16 bits signed
-    LONG,               // pass by value            32 bits signed
-    FLOAT,              // pass by value            machine dependent
-    BOOL,               // pass by value            bit 0 of an 8-bit byte
-    STR,                // pass by reference
-    ARRAY,              // pass by reference, subtype is the element type
-    ARRAY_SPLITW,       // pass by reference, split word layout, subtype is the element type (restricted to word types)
-    POINTER,            // typed pointer, subtype is whatever type is pointed to
-    STRUCT_INSTANCE,    // the actual instance of a struct (not directly supported in the language yet, but we need its type)
-    ARRAY_POINTER,      // array of pointers (uwords), subtype is whatever type each element points to
-    UNDEFINED;
-
-
-    fun largerSizeThan(other: BaseDataType) =
-        when {
-            this == other -> false
-            this.isByteOrBool -> false
-            this.isWord -> other.isByteOrBool
-            this == LONG -> other.isByteOrBool || other.isWord
-            this == STR && other == UWORD || this == UWORD && other == STR -> false
-            this.isArray && other.isArray -> false
-            this.isArray -> other != FLOAT
-            this == STR -> other != FLOAT
-            this.isPointer -> other.isByteOrBool
-            else -> true
-        }
-
-    fun equalsSize(other: BaseDataType) =
-        when {
-            this == other -> true
-            this.isArray && other.isArray -> true
-            this.isByteOrBool -> other.isByteOrBool
-            this.isWord -> other.isWord || other.isPointer
-            this.isPointer -> other.isWord
-            this == STR && other== UWORD || this== UWORD && other== STR -> true
-            this == STR && other.isArray -> true
-            this.isArray && other == STR -> true
-            else -> false
-        }
-}
-
-val BaseDataType.isByte get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE)
-val BaseDataType.isByteOrBool get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.BOOL)
-val BaseDataType.isWord get() = this in arrayOf(BaseDataType.UWORD, BaseDataType.WORD)
-val BaseDataType.isLong get() = this == BaseDataType.LONG
-val BaseDataType.isInteger get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG)
-val BaseDataType.isIntegerOrBool get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.LONG, BaseDataType.BOOL)
-val BaseDataType.isWordOrByteOrBool get() = this in arrayOf(BaseDataType.UBYTE, BaseDataType.BYTE, BaseDataType.UWORD, BaseDataType.WORD, BaseDataType.BOOL)
-val BaseDataType.isNumeric get() = this == BaseDataType.FLOAT || this.isInteger
-val BaseDataType.isNumericOrBool get() = this == BaseDataType.BOOL || this.isNumeric
-val BaseDataType.isSigned get() = this in arrayOf(BaseDataType.BYTE, BaseDataType.WORD, BaseDataType.LONG, BaseDataType.FLOAT)
-val BaseDataType.isArray get() = this == BaseDataType.ARRAY || this == BaseDataType.ARRAY_SPLITW || this == BaseDataType.ARRAY_POINTER
-val BaseDataType.isPointer get() = this == BaseDataType.POINTER
-val BaseDataType.isStructInstance get() = this == BaseDataType.STRUCT_INSTANCE
-val BaseDataType.isPointerArray get() = this == BaseDataType.ARRAY_POINTER
-val BaseDataType.isSplitWordArray get() = this == BaseDataType.ARRAY_SPLITW || this == BaseDataType.ARRAY_POINTER       // pointer arrays are also always stored as split uwords
-val BaseDataType.isIterable get() =  this in arrayOf(BaseDataType.STR, BaseDataType.ARRAY, BaseDataType.ARRAY_SPLITW, BaseDataType.ARRAY_POINTER)
-val BaseDataType.isPassByRef get() = this.isIterable && !this.isPointer
-val BaseDataType.isPassByValue get() = !this.isIterable || this.isPointer
-
-
-interface ISubType {
-    val scopedNameString: String
-    fun memsize(sizer: IMemSizer): Int
-    fun sameas(other: ISubType): Boolean
-    fun getFieldType(name: String): DataType?
-}
-
-class DataType private constructor(val base: BaseDataType, val sub: BaseDataType?, var subType: ISubType?, var subTypeFromAntlr: List<String>?=null) {
-
-    init {
-        when {
-            base.isPointerArray -> {
-                require(sub!=null || subType!=null || subTypeFromAntlr!=null)
-            }
-            base.isArray -> {
-                require(sub != null && subType==null && subTypeFromAntlr==null)
-                if(base.isSplitWordArray)
-                    require(sub == BaseDataType.UWORD || sub == BaseDataType.WORD)
-            }
-            base==BaseDataType.STR -> require(sub==BaseDataType.UBYTE) { "string subtype should be ubyte" }
-            base!=BaseDataType.POINTER -> require(sub == null) { "only string, array and pointer base types can have a subtype"}
-            else -> {
-                require(sub == null || (subType == null && subTypeFromAntlr == null)) {
-                    "sub and subtype can't both be set"
-                }
-            }
-        }
-    }
-
-    override fun equals(other: Any?): Boolean {
-        if (this === other) return true
-        if (other !is DataType) return false
-        return base == other.base && sub == other.sub && (subType==other.subType || subType!!.sameas(other.subType!!))
-    }
-
-    override fun hashCode(): Int = Objects.hash(base, sub, subType)
-
-    fun setActualSubType(actualSubType: ISubType) {
-        subType = actualSubType
-        subTypeFromAntlr = null
-    }
-
-    companion object {
-
-        val UBYTE = DataType(BaseDataType.UBYTE, null, null)
-        val BYTE = DataType(BaseDataType.BYTE, null, null)
-        val UWORD = DataType(BaseDataType.UWORD, null, null)
-        val WORD = DataType(BaseDataType.WORD, null, null)
-        val LONG = DataType(BaseDataType.LONG, null, null)
-        val FLOAT = DataType(BaseDataType.FLOAT, null, null)
-        val BOOL = DataType(BaseDataType.BOOL, null, null)
-        val STR = DataType(BaseDataType.STR, BaseDataType.UBYTE, null)
-        val UNDEFINED = DataType(BaseDataType.UNDEFINED, null, null)
-
-        private val simpletypes = mapOf(
-            BaseDataType.UBYTE to DataType(BaseDataType.UBYTE, null, null),
-            BaseDataType.BYTE to DataType(BaseDataType.BYTE, null, null),
-            BaseDataType.UWORD to DataType(BaseDataType.UWORD, null, null),
-            BaseDataType.WORD to DataType(BaseDataType.WORD, null, null),
-            BaseDataType.LONG to DataType(BaseDataType.LONG, null, null),
-            BaseDataType.FLOAT to DataType(BaseDataType.FLOAT, null, null),
-            BaseDataType.BOOL to DataType(BaseDataType.BOOL, null, null),
-            BaseDataType.STR to DataType(BaseDataType.STR, BaseDataType.UBYTE, null),
-            BaseDataType.UNDEFINED to DataType(BaseDataType.UNDEFINED, null, null)
-        )
-
-        fun forDt(dt: BaseDataType): DataType {
-            if(dt.isStructInstance)
-                TODO("cannot use struct instance as a data type (yet) - use a pointer instead")
-            return simpletypes.getValue(dt)
-        }
-
-        fun arrayFor(elementDt: BaseDataType, splitwordarray: Boolean=true): DataType {
-            require(!elementDt.isPointer) { "use other array constructor for arrays of pointers" }
-            val actualElementDt = if(elementDt==BaseDataType.STR) BaseDataType.UWORD else elementDt      // array of strings is actually just an array of UWORD pointers
-            return if(splitwordarray && actualElementDt.isWord)
-                DataType(BaseDataType.ARRAY_SPLITW, actualElementDt, null)
-            else {
-                if(actualElementDt.isNumericOrBool)
-                    DataType(BaseDataType.ARRAY, actualElementDt, null)
-                else
-                    throw NoSuchElementException("invalid basic element dt $elementDt")
-            }
-        }
-
-        fun arrayOfPointersTo(sub: BaseDataType): DataType = DataType(BaseDataType.ARRAY_POINTER, sub, null)
-        fun arrayOfPointersTo(structType: ISubType?): DataType = DataType(BaseDataType.ARRAY_POINTER, null, structType)
-        fun arrayOfPointersFromAntlrTo(sub: BaseDataType?, identifier: List<String>?): DataType =
-            DataType(BaseDataType.ARRAY_POINTER, sub, null, identifier)
-
-        fun pointer(base: BaseDataType): DataType = DataType(BaseDataType.POINTER, base, null)
-        fun pointer(dt: DataType): DataType = if(dt.isBasic)
-                DataType(BaseDataType.POINTER, dt.base, null)
-            else
-                DataType(BaseDataType.POINTER, null, dt.subType, dt.subTypeFromAntlr)
-        fun pointer(structType: ISubType): DataType = DataType(BaseDataType.POINTER, null, structType)
-        fun pointerFromAntlr(identifier: List<String>): DataType = DataType(BaseDataType.POINTER, null, null, identifier)
-        fun structInstance(type: ISubType?): DataType = DataType(BaseDataType.STRUCT_INSTANCE, sub=null, type)
-        fun structInstanceFromAntlr(struct: List<String>): DataType = DataType(BaseDataType.STRUCT_INSTANCE, null, null, subTypeFromAntlr = struct)
-    }
-
-
-    fun elementToArray(splitwords: Boolean = true): DataType {
-        return if (base == BaseDataType.UWORD || base == BaseDataType.WORD || base == BaseDataType.STR) arrayFor(base, splitwords)
-        else arrayFor(base, false)
-    }
-
-    fun elementType(): DataType =
-        when {
-            isPointerArray -> DataType(BaseDataType.POINTER, sub, subType)
-            base.isArray || base==BaseDataType.STR -> forDt(sub!!)
-            else -> throw IllegalArgumentException("not an array")
-        }
-
-    fun typeForAddressOf(msb: Boolean): DataType {
-        if (isUndefined)
-            return if(msb) pointer(BaseDataType.UBYTE) else UWORD
-        else {
-            if (isBasic)
-                return pointer(base)
-            if (isString)
-                return pointer(BaseDataType.UBYTE)
-            if (isPointer)
-                return UWORD
-            if (isArray) {
-                if (msb || isSplitWordArray)
-                    return pointer(BaseDataType.UBYTE)
-                val elementDt = elementType()
-                require(elementDt.isBasic)
-                return pointer(elementDt)
-            }
-            if (subType != null)
-                return pointer(this)
-            return UWORD
-        }
-    }
-
-    fun dereference(): DataType {
-        require(isPointer || isUnsignedWord)
-        return when {
-            isUnsignedWord -> forDt(BaseDataType.UBYTE)
-            sub!=null -> forDt(sub)
-            subType!=null -> DataType(BaseDataType.STRUCT_INSTANCE, null, subType)
-            subTypeFromAntlr!=null -> DataType(BaseDataType.STRUCT_INSTANCE, null, null, subTypeFromAntlr)
-            else -> throw IllegalArgumentException("cannot dereference this pointer type")
-        }
-    }
-
-    override fun toString(): String = when(base) {
-        BaseDataType.ARRAY -> {
-            when(sub) {
-                BaseDataType.BOOL -> "bool[]"
-                BaseDataType.FLOAT -> "float[]"
-                BaseDataType.BYTE -> "byte[]"
-                BaseDataType.WORD -> "word[]"
-                BaseDataType.UBYTE -> "ubyte[]"
-                BaseDataType.UWORD -> "uword[]"
-                BaseDataType.LONG -> "long[]"
-                else -> throw IllegalArgumentException("invalid sub type")
-            }
-        }
-        BaseDataType.ARRAY_SPLITW -> {
-            when(sub) {
-                BaseDataType.WORD -> "word[] (split)"
-                BaseDataType.UWORD -> "uword[] (split)"
-                else -> throw IllegalArgumentException("invalid sub type")
-            }
-        }
-        BaseDataType.POINTER -> {
-            if(sub!=null) "^^${sub.name.lowercase()}" else if(subType!=null) "^^${subType!!.scopedNameString}" else "^^${subTypeFromAntlr}"
-        }
-        BaseDataType.ARRAY_POINTER -> {
-            if(sub!=null) "^^${sub.name.lowercase()}[] (split)" else if (subType!=null) "^^${subType!!.scopedNameString}[] (split)" else "^^${subTypeFromAntlr}[] (split)"
-        }
-        BaseDataType.STRUCT_INSTANCE -> {
-            sub?.name?.lowercase() ?: if (subType!=null) subType!!.scopedNameString else "$subTypeFromAntlr"
-        }
-        else -> base.name.lowercase()
-    }
-
-    fun sourceString(): String = when (base) {
-        BaseDataType.BOOL -> "bool"
-        BaseDataType.UBYTE -> "ubyte"
-        BaseDataType.BYTE -> "byte"
-        BaseDataType.UWORD -> "uword"
-        BaseDataType.WORD -> "word"
-        BaseDataType.LONG -> "long"
-        BaseDataType.FLOAT -> "float"
-        BaseDataType.STR -> "str"
-        BaseDataType.POINTER -> {
-            when {
-                sub!=null -> "^^${sub.name.lowercase()}"
-                subType!=null -> "^^${subType!!.scopedNameString}"
-                subTypeFromAntlr!=null -> "^^${subTypeFromAntlr!!.joinToString(".")}"
-                else -> "?????"
-            }
-        }
-        BaseDataType.STRUCT_INSTANCE -> {
-            when {
-                sub!=null -> sub.name.lowercase()
-                subType!=null -> subType!!.scopedNameString
-                subTypeFromAntlr!=null -> subTypeFromAntlr!!.joinToString(".")
-                else -> "?????"
-            }
-        }
-        BaseDataType.ARRAY_POINTER -> {
-            when {
-                sub!=null -> "^^${sub.name.lowercase()}["
-                subType!=null -> "^^${subType!!.scopedNameString}["
-                subTypeFromAntlr!=null -> "^^${subTypeFromAntlr!!.joinToString(".")}["
-                else -> "????? ["
-            }
-        }
-        BaseDataType.ARRAY -> {
-            when(sub) {
-                BaseDataType.UBYTE -> "ubyte["
-                BaseDataType.UWORD -> "@nosplit uword["
-                BaseDataType.BOOL -> "bool["
-                BaseDataType.BYTE -> "byte["
-                BaseDataType.WORD -> "@nosplit word["
-                BaseDataType.LONG -> "long["
-                BaseDataType.FLOAT -> "float["
-                else -> throw IllegalArgumentException("invalid sub type")
-            }
-        }
-        BaseDataType.ARRAY_SPLITW -> {
-            when(sub) {
-                BaseDataType.UWORD -> "uword["
-                BaseDataType.WORD -> "word["
-                else -> throw IllegalArgumentException("invalid sub type")
-            }
-        }
-        BaseDataType.UNDEFINED -> throw IllegalArgumentException("wrong dt")
-    }
-
-    // is the type assignable to the given other type (perhaps via a typecast) without loss of precision?
-    infix fun isAssignableTo(targetType: DataType) =
-        when(base) {
-            BaseDataType.BOOL -> targetType.base == BaseDataType.BOOL
-            BaseDataType.UBYTE -> targetType.base in arrayOf(BaseDataType.UBYTE, BaseDataType.WORD, BaseDataType.UWORD, BaseDataType.LONG, BaseDataType.FLOAT)
-            BaseDataType.BYTE -> targetType.base in arrayOf(BaseDataType.BYTE, BaseDataType.WORD, BaseDataType.LONG, BaseDataType.FLOAT)
-            BaseDataType.UWORD -> targetType.base in arrayOf(BaseDataType.UWORD, BaseDataType.LONG, BaseDataType.FLOAT, BaseDataType.POINTER, BaseDataType.ARRAY_POINTER)
-            BaseDataType.WORD -> targetType.base in arrayOf(BaseDataType.WORD, BaseDataType.LONG, BaseDataType.FLOAT)
-            BaseDataType.LONG -> targetType.base in arrayOf(BaseDataType.LONG, BaseDataType.FLOAT)
-            BaseDataType.FLOAT -> targetType.base in arrayOf(BaseDataType.FLOAT)
-            BaseDataType.STR -> targetType.base in arrayOf(BaseDataType.STR, BaseDataType.UWORD) || (targetType.isPointer && targetType.sub==BaseDataType.UBYTE)
-            BaseDataType.ARRAY, BaseDataType.ARRAY_SPLITW -> targetType.base in arrayOf(BaseDataType.ARRAY, BaseDataType.ARRAY_SPLITW) && targetType.sub == sub
-            BaseDataType.POINTER -> {
-                when {
-                    targetType.base == BaseDataType.UWORD || targetType.base == BaseDataType.LONG -> true
-                    targetType.isPointer -> this.isUnsignedWord || this == targetType
-                    else -> false
-                }
-            }
-            BaseDataType.STRUCT_INSTANCE -> false        // we cannot deal with actual struct instances yet in any shape or form (only getting fields from it)
-            BaseDataType.ARRAY_POINTER -> false
-            BaseDataType.UNDEFINED -> false
-        }
-
-    fun largerSizeThan(other: DataType): Boolean = base.largerSizeThan(other.base)
-    fun equalsSize(other: DataType): Boolean = base.equalsSize(other.base)
-
-    // note: for pointer types, size() doesn't return the size of the pointer itself but the size of the thing it points to
-    fun size(memsizer: IMemSizer): Int = if(sub!=null) {
-            memsizer.memorySize(sub)
-        } else if(subType!=null) {
-            subType!!.memsize(memsizer)
-        } else {
-            memsizer.memorySize(base)
-        }
-
-    val isBasic = sub==null && subType==null && subTypeFromAntlr==null
-    val isUndefined = base == BaseDataType.UNDEFINED
-    val isByte = base.isByte
-    val isUnsignedByte = base == BaseDataType.UBYTE
-    val isSignedByte = base == BaseDataType.BYTE
-    val isByteOrBool = base.isByteOrBool
-    val isWord = base.isWord
-    val isUnsignedWord =  base == BaseDataType.UWORD
-    val isSignedWord =  base == BaseDataType.WORD
-    val isInteger = base.isInteger
-    val isWordOrByteOrBool = base.isWordOrByteOrBool
-    val isIntegerOrBool = base.isIntegerOrBool
-    val isNumeric = base.isNumeric
-    val isNumericOrBool = base.isNumericOrBool
-    val isSigned = base.isSigned
-    val isUnsigned = !base.isSigned
-    val isArray = base.isArray
-    val isPointer = base.isPointer
-    val isPointerToByte = base.isPointer && sub?.isByteOrBool==true
-    val isPointerToWord = base.isPointer && sub?.isWord==true
-    val isStructInstance = base.isStructInstance
-    val isPointerArray = base.isPointerArray
-    val isBoolArray = base.isArray && !base.isPointerArray && sub == BaseDataType.BOOL
-    val isByteArray = base.isArray && !base.isPointerArray && (sub == BaseDataType.UBYTE || sub == BaseDataType.BYTE)
-    val isUnsignedByteArray = base.isArray && !base.isPointerArray && sub == BaseDataType.UBYTE
-    val isSignedByteArray = base.isArray && !base.isPointerArray && sub == BaseDataType.BYTE
-    val isWordArray = base.isArray && !base.isPointerArray && (sub == BaseDataType.UWORD || sub == BaseDataType.WORD)
-    val isUnsignedWordArray = base.isArray && !base.isPointerArray && sub == BaseDataType.UWORD
-    val isSignedWordArray = base.isArray && !base.isPointerArray && sub == BaseDataType.WORD
-    val isLongArray = base.isArray && sub == BaseDataType.LONG
-    val isFloatArray = base.isArray && !base.isPointerArray && sub == BaseDataType.FLOAT
-    val isString = base == BaseDataType.STR
-    val isBool = base == BaseDataType.BOOL
-    val isFloat = base == BaseDataType.FLOAT
-    val isLong = base == BaseDataType.LONG
-    val isStringly = base == BaseDataType.STR || base == BaseDataType.UWORD || (base == BaseDataType.ARRAY && (sub == BaseDataType.UBYTE || sub == BaseDataType.BYTE))
-    val isSplitWordArray = base.isSplitWordArray
-    val isSplitUnsignedWordArray = base.isSplitWordArray && !base.isPointerArray && sub == BaseDataType.UWORD
-    val isSplitSignedWordArray = base.isSplitWordArray && !base.isPointerArray && sub == BaseDataType.WORD
-    val isIterable =  base.isIterable
-    val isPassByRef = base.isPassByRef
-    val isPassByValue = base.isPassByValue
-}
-

 enum class CpuRegister {
    A,
@@ -402,10 +20,10 @@ enum class RegisterOrPair {
    R0, R1, R2, R3, R4, R5, R6, R7,
    R8, R9, R10, R11, R12, R13, R14, R15,
    // combined virtual registers to store 32 bits longs:
-    R0R1_32, R2R3_32, R4R5_32, R6R7_32, R8R9_32, R10R11_32, R12R13_32, R14R15_32;
+    R0R1, R2R3, R4R5, R6R7, R8R9, R10R11, R12R13, R14R15;

    companion object {
-        val names by lazy { entries.map { it.toString()} }
+        val names: Set<String> = entries.map { it.toString() }.toSet()
        fun fromCpuRegister(cpu: CpuRegister): RegisterOrPair {
            return when(cpu) {
                CpuRegister.A -> A
@@ -415,15 +33,19 @@ enum class RegisterOrPair {
        }
    }

+    /**
+     * Returns the starting virtual register name for the current 32-bit combined virtual register
+     * @return The starting register name as a string, WITHOUT THE cx16 block scope prefix!
+     */
    fun startregname() = when(this) {
-        R0R1_32 -> "r0"
-        R2R3_32 -> "r2"
-        R4R5_32 -> "r4"
-        R6R7_32 -> "r6"
-        R8R9_32 -> "r8"
-        R10R11_32 -> "r10"
-        R12R13_32 -> "r12"
-        R14R15_32 -> "r14"
+        R0R1 -> "r0"
+        R2R3 -> "r2"
+        R4R5 -> "r4"
+        R6R7 -> "r6"
+        R8R9 -> "r8"
+        R10R11 -> "r10"
+        R12R13 -> "r12"
+        R14R15 -> "r14"
        else -> throw IllegalArgumentException("must be a combined virtual register $this")
    }

@@ -435,19 +57,20 @@ enum class RegisterOrPair {
    }

    fun asScopedNameVirtualReg(type: DataType?): List<String> {
-        require(this in Cx16VirtualRegisters)
+        require(this in Cx16VirtualRegisters || this in CombinedLongRegisters)
        val suffix = when(type?.base) {
            BaseDataType.UBYTE, BaseDataType.BOOL -> "L"
            BaseDataType.BYTE -> "sL"
            BaseDataType.WORD -> "s"
            BaseDataType.UWORD, BaseDataType.POINTER, null -> ""
+            BaseDataType.LONG -> "sl"
            else -> throw IllegalArgumentException("invalid register param type for cx16 virtual reg")
        }
        return listOf("cx16", name.lowercase()+suffix)
    }

    fun isWord() = this==AX || this == AY || this==XY || this in Cx16VirtualRegisters
-    fun isLong() = this in combinedLongRegisters
+    fun isLong() = this in CombinedLongRegisters

 }       // only used in parameter and return value specs in asm subroutines

@@ -458,7 +81,7 @@ enum class Statusflag {
    Pn;     // don't use

    companion object {
-        val names by lazy { entries.map { it.toString()} }
+        val names: Set<String> = entries.map { it.toString() }.toSet()
    }
 }

@@ -477,25 +100,25 @@ enum class BranchCondition {
    VC
 }

-val Cx16VirtualRegisters = arrayOf(
+val Cx16VirtualRegisters = setOf(
    RegisterOrPair.R0, RegisterOrPair.R1, RegisterOrPair.R2, RegisterOrPair.R3,
    RegisterOrPair.R4, RegisterOrPair.R5, RegisterOrPair.R6, RegisterOrPair.R7,
    RegisterOrPair.R8, RegisterOrPair.R9, RegisterOrPair.R10, RegisterOrPair.R11,
    RegisterOrPair.R12, RegisterOrPair.R13, RegisterOrPair.R14, RegisterOrPair.R15
 )

-val combinedLongRegisters = arrayOf(
-    RegisterOrPair.R0R1_32,
-    RegisterOrPair.R2R3_32,
-    RegisterOrPair.R4R5_32,
-    RegisterOrPair.R6R7_32,
-    RegisterOrPair.R8R9_32,
-    RegisterOrPair.R10R11_32,
-    RegisterOrPair.R12R13_32,
-    RegisterOrPair.R14R15_32
+val CombinedLongRegisters = setOf(
+    RegisterOrPair.R0R1,
+    RegisterOrPair.R2R3,
+    RegisterOrPair.R4R5,
+    RegisterOrPair.R6R7,
+    RegisterOrPair.R8R9,
+    RegisterOrPair.R10R11,
+    RegisterOrPair.R12R13,
+    RegisterOrPair.R14R15
 )

-val CpuRegisters = arrayOf(
+val CpuRegisters = setOf(
    RegisterOrPair.A, RegisterOrPair.X, RegisterOrPair.Y,
    RegisterOrPair.AX, RegisterOrPair.AY, RegisterOrPair.XY
 )
@@ -531,4 +154,4 @@ enum class ZeropageWish {
 enum class SplitWish {
    DONTCARE,
    NOSPLIT
-}
+}
@@ -2,10 +2,48 @@ package prog8.code.core

 import java.nio.file.Path

-enum class CpuType {
-    CPU6502,
-    CPU65C02,
-    VIRTUAL
+/**
+ * Identifies the target CPU type and its key characteristics that affect IR semantics.
+ *
+ * The most important property is [statusBitsOnMultiByteOps], which controls the IR
+ * status-bit contract (see IRInstructions.kt for the full spec):
+ *
+ * - When `true`, the IR generator is allowed to skip emitting explicit CMP/CMPI before
+ *   branches that depend on the result of a previous "status-setting" instruction
+ *   (LOAD, INC, DEC, AND, OR, XOR, etc.). The contract is: "this instruction sets
+ *   Z and N based on the full multi-byte value." Backends for these targets must
+ *   honor this contract (e.g., M68000's `move.w #imm,d0` naturally sets Z based on
+ *   the 16-bit value, so the IR can rely on it).
+ *
+ * - When `false`, multi-byte operations on this target do NOT set status bits
+ *   correctly for the full value (e.g., 6502's `dec lo` only sets Z based on the
+ *   low byte of a 16-bit decrement). The IR generator must therefore always emit
+ *   an explicit CMP/CMPI before any branch that depends on the result. Backends
+ *   for these targets should NOT add `ora` postambles to set Z; instead they
+ *   rely on the explicit CMP/CMPI emitted by the IR generator.
+ *
+ *   For 8-bit CPUs (6502, 65C02) the natural status flags from a multi-byte
+ *   cascade are misleading: Z is set based on the LAST byte operated on, not
+ *   the full value. So we treat the contract as "no instruction sets status
+ *   bits except CMP/CMPI/SEC/CLC/SGN/BITTST" and have the IR generator emit
+ *   explicit compares. This avoids the trap of "this works for BYTE but
+ *   silently breaks for WORD/LONG".
+ */
+enum class CpuType(val statusBitsOnMultiByteOps: Boolean) {
+    /** 8-bit NMOS 6502. Multi-byte ops don't set Z based on full value. */
+    CPU6502(false),
+
+    /** 8-bit CMOS 65C02. Same status-bit issue as plain 6502. */
+    CPU65C02(false),
+
+    /**
+     * Virtual machine target. We use `false` here so the IR generator always
+     * emits explicit CMP/CMPI; the VM's setResultReg then does NOT set Z/N
+     * flags (only CMP/CMPI/SEC/CLC/SGN/BITTST do). This matches the VM's
+     * existing documentation (VirtualMachine.kt top comment) and keeps the
+     * behavior consistent across all current targets.
+     */
+    VIRTUAL(false)
 }

 interface ICompilationTarget: IStringEncoding, IMemSizer {
@@ -13,8 +51,7 @@ interface ICompilationTarget: IStringEncoding, IMemSizer {

    val FLOAT_MAX_NEGATIVE: Double
    val FLOAT_MAX_POSITIVE: Double
-    val FLOAT_MEM_SIZE: Int
-    val STARTUP_CODE_RESERVED_SIZE: UInt        // this is here, so that certain compiler targets are able to tune this
+    val FLOAT_MEM_SIZE: UInt
    val PROGRAM_LOAD_ADDRESS : UInt
    val PROGRAM_MEMTOP_ADDRESS: UInt
    val BSSHIGHRAM_START: UInt
@@ -24,11 +61,12 @@ interface ICompilationTarget: IStringEncoding, IMemSizer {

    val cpu: CpuType
    var zeropage: Zeropage
-    var golden: GoldenRam
    val libraryPath: Path?
    val customLauncher: List<String>
    val additionalAssemblerOptions: List<String>
    val defaultOutputType: OutputType
+    val defaultLauncherType: CbmPrgLauncherType
+    val supportsBankedCalls: Boolean

    fun initializeMemoryAreas(compilerOptions: CompilationOptions)
    fun getFloatAsmBytes(num: Number): String
@@ -4,7 +4,7 @@ interface IErrorReporter {
    fun err(msg: String, position: Position)
    fun warn(msg: String, position: Position)
    fun info(msg: String, position: Position)
-    fun undefined(symbol: List<String>, position: Position)
+    fun undefined(symbol: List<String>, suggestImport: Boolean=false, position: Position)
    fun noErrors(): Boolean
    fun report()
    fun finalizeNumErrors(numErrors: Int, numWarnings: Int, numInfos: Int) {
@@ -28,26 +28,21 @@ abstract class Zeropage(options: CompilationOptions): MemoryAllocator(options) {
    abstract val SCRATCH_PTR : UInt     // temp storage for a pointer


-    // the variables allocated into Zeropage.
+    // Collections for zeropage allocation (single-threaded usage)
    // name (scoped) ==> pair of address to (Datatype + bytesize)
    val allocatedVariables = mutableMapOf<String, VarAllocation>()
-
-    val free = mutableListOf<UInt>()     // subclasses must set this to the appropriate free locations.
+    val free = mutableSetOf<UInt>()     // subclasses must set this to the appropriate free locations.

    fun removeReservedFromFreePool() {
-        synchronized(this) {
-            for (reserved in options.zpReserved)
-                reserve(reserved)
+        for (reserved in options.zpReserved)
+            reserve(reserved)

-            free.removeAll(arrayOf(SCRATCH_B1, SCRATCH_REG, SCRATCH_W1, SCRATCH_W1 + 1u, SCRATCH_W2, SCRATCH_W2 + 1u, SCRATCH_PTR, SCRATCH_PTR+1u))
-        }
+        free.removeAll(setOf(SCRATCH_B1, SCRATCH_REG, SCRATCH_W1, SCRATCH_W1 + 1u, SCRATCH_W2, SCRATCH_W2 + 1u, SCRATCH_PTR, SCRATCH_PTR+1u))
    }

    fun retainAllowed() {
-        synchronized(this) {
-            for(allowed in options.zpAllowed)
-                free.retainAll { it in allowed }
-        }
+        for(allowed in options.zpAllowed)
+            free.retainAll { it in allowed }
    }

    fun availableBytes() = if(options.zeropage== ZeropageType.DONTUSE) 0 else free.size
@@ -65,7 +60,7 @@ abstract class Zeropage(options: CompilationOptions): MemoryAllocator(options) {
                          position: Position?,
                          errors: IErrorReporter): Result<VarAllocation, MemAllocationError> {

-        require(name.isEmpty() || name !in allocatedVariables) {"name can't be allocated twice"}
+        require(name.isEmpty() || !allocatedVariables.containsKey(name)) {"name can't be allocated twice"}

        if(options.zeropage== ZeropageType.DONTUSE)
            return Err(MemAllocationError("zero page usage has been disabled"))
@@ -95,19 +90,17 @@ abstract class Zeropage(options: CompilationOptions): MemoryAllocator(options) {
                    else -> throw MemAllocationError("weird dt")
                }

-        synchronized(this) {
-            if(free.isNotEmpty()) {
-                if(size==1) {
-                    for(candidate in free.minOrNull()!! .. free.maxOrNull()!!+1u) {
-                        if(oneSeparateByteFree(candidate))
-                            return Ok(VarAllocation(makeAllocation(candidate, 1, datatype, name), datatype,1))
-                    }
-                    return Ok(VarAllocation(makeAllocation(free[0], 1, datatype, name), datatype,1))
-                }
+        if(free.isNotEmpty()) {
+            if(size==1) {
                for(candidate in free.minOrNull()!! .. free.maxOrNull()!!+1u) {
-                    if (sequentialFree(candidate, size))
-                        return Ok(VarAllocation(makeAllocation(candidate, size, datatype, name), datatype, size))
+                    if(oneSeparateByteFree(candidate))
+                        return Ok(VarAllocation(makeAllocation(candidate, 1, datatype, name), datatype,1))
                }
+                return Ok(VarAllocation(makeAllocation(free.first(), 1, datatype, name), datatype,1))
+            }
+            for(candidate in free.minOrNull()!! .. free.maxOrNull()!!+1u) {
+                if (sequentialFree(candidate, size))
+                    return Ok(VarAllocation(makeAllocation(candidate, size, datatype, name), datatype, size))
            }
        }

@@ -131,43 +124,12 @@ abstract class Zeropage(options: CompilationOptions): MemoryAllocator(options) {
        return address
    }

-    private fun oneSeparateByteFree(address: UInt) = address in free && address-1u !in free && address+1u !in free
+    private fun oneSeparateByteFree(address: UInt) = 
+        address in free && 
+        (address == 0u || address-1u !in free) && 
+        address+1u !in free
    private fun sequentialFree(address: UInt, size: Int): Boolean {
        require(size>0)
        return free.containsAll((address until address+size.toUInt()).toList())
    }
 }
-
-
-// TODO: this class is not yet used
-class GoldenRam(options: CompilationOptions, val region: UIntRange): MemoryAllocator(options) {
-    private var nextLocation: UInt = region.first
-
-    override fun allocate(
-        name: String,
-        datatype: DataType,
-        numElements: Int?,
-        position: Position?,
-        errors: IErrorReporter): Result<VarAllocation, MemAllocationError> {
-
-        val size: Int =
-            when {
-                datatype.isIntegerOrBool -> options.compTarget.memorySize(datatype, null)
-                datatype.isString -> numElements!!
-                datatype.isArray -> options.compTarget.memorySize(datatype, numElements!!)
-                datatype.isFloat -> {
-                    if (options.floats) {
-                        options.compTarget.memorySize(DataType.FLOAT, null)
-                    } else return Err(MemAllocationError("floating point option not enabled"))
-                }
-                else -> throw MemAllocationError("weird dt")
-            }
-
-        return if(nextLocation<=region.last && (region.last + 1u - nextLocation) >= size.toUInt()) {
-            val result = Ok(VarAllocation(nextLocation, datatype, size))
-            nextLocation += size.toUInt()
-            result
-        } else
-            Err(MemAllocationError("no more free space in Golden RAM to allocate $size sequential bytes"))
-    }
-}
@@ -1,10 +1,10 @@
 package prog8.code.core

-val AssociativeOperators = arrayOf("+", "*", "&", "|", "^", "==", "!=", "xor")       // note: and,or are not associative because of Shortcircuit/McCarthy evaluation
-val ComparisonOperators = arrayOf("==", "!=", "<", ">", "<=", ">=")
-val LogicalOperators = arrayOf("and", "or", "xor", "not", "in")
-val BitwiseOperators = arrayOf("&", "|", "^", "~")
-val PrefixOperators = arrayOf("+", "-", "~", "not")
+val CommutativeOperators = setOf("+", "*", "&", "|", "^", "==", "!=", "xor")       // note: and,or are not commutative because of Shortcircuit/McCarthy evaluation
+val ComparisonOperators = setOf("==", "!=", "<", ">", "<=", ">=")
+val LogicalOperators = setOf("and", "or", "xor", "not", "in")
+val BitwiseOperators = setOf("&", "|", "^", "~")
+val PrefixOperators = setOf("+", "-", "~", "not")

 fun invertedComparisonOperator(operator: String) =
    when (operator) {
@@ -5,14 +5,17 @@ import prog8.code.source.SourceCode
 import java.nio.file.InvalidPathException
 import kotlin.io.path.Path

-data class Position(val file: String, val line: Int, val startCol: Int, val endCol: Int) {
-    override fun toString(): String = "[$file: line $line col ${startCol}-${endCol}]"
-
-    init {
-        if(!file.startsWith('~') ||!file.endsWith('~'))
-            require(line>0 && startCol>=0 && endCol>=startCol) {
-                "Invalid position: $this"
-            }
+/**
+ * Source code position.
+ */
+data class Position(
+    val file: String,
+    val line: Int,           // line number (1-based)
+    val startCol: Int,       // start column (1-based, tab-expanded)
+    val endCol: Int          // end column (1-based, tab-expanded)
+) {
+    override fun toString(): String {
+        return "[$file: line $line col ${startCol}-${endCol}]"
    }

    fun toClickableStr(): String {
@@ -21,8 +24,8 @@ data class Position(val file: String, val line: Int, val startCol: Int, val endC
        if(SourceCode.isLibraryResource(file))
            return "$file:$line:$startCol:"
        return try {
-            val path = Path(file).sanitize().toString()
-            "file://$path:$line:$startCol:"
+            val path = Path(file).sanitize().toUri().toString()
+            "$path:$line:$startCol:"
        } catch(_: InvalidPathException) {
            // this can occur on Windows when the source origin contains "invalid" characters such as ':'
            "file://$file:$line:$startCol:"
@@ -32,4 +35,4 @@ data class Position(val file: String, val line: Int, val startCol: Int, val endC
    companion object {
        val DUMMY = Position("~dummy~", 0, 0, 0)
    }
-}
+}
@@ -3,18 +3,20 @@ package prog8.code.source
 import prog8.code.core.Position
 import prog8.code.sanitize
 import java.nio.file.Path
-import java.util.*
+import java.util.concurrent.ConcurrentHashMap
 import kotlin.io.path.Path


 // Resource caching "filesystem".
 // Note that it leaves the decision to load a resource or an actual disk file to the caller.
+// Thread-safe: uses ConcurrentHashMap for all caches.

 object ImportFileSystem {

+    val userHome: Path get() = Path.of(System.getProperty("user.home"))
+
    fun expandTilde(path: String): String = if (path.startsWith("~")) {
-        val userHome = System.getProperty("user.home")
-        userHome + path.drop(1)
+        userHome.toString() + path.drop(1)
    } else {
        path
    }
@@ -23,45 +25,45 @@ object ImportFileSystem {

    fun getFile(path: Path, isLibrary: Boolean=false): SourceCode {
        val normalized = path.sanitize()
-        val cached = cache[normalized.toString()]
-        if (cached != null)
-            return cached
-        val file = SourceCode.File(normalized, isLibrary)
-        cache[normalized.toString()] = file
-        return file
+        return cache.computeIfAbsent(normalized.toString().lowercase()) {
+            SourceCode.File(normalized, isLibrary)
+        }
    }

    fun getResource(name: String): SourceCode {
-        val cached = cache[name]
-        if (cached != null) return cached
-        val resource = SourceCode.Resource(name)
-        cache[name] = resource
-        return resource
+        return cache.computeIfAbsent(name.lowercase()) {
+            SourceCode.Resource(name)
+        }
+    }
+
+    fun clearCaches() {
+        cache.clear()
+        lineSpanCache.clear()
    }

    fun retrieveSourceLine(position: Position): String {
        if(SourceCode.isLibraryResource(position.file)) {
-            val cached = cache[SourceCode.withoutPrefix(position.file)]
+            val key = SourceCode.withoutPrefix(position.file)
+            val cached = cache[key.lowercase()]
+                ?: runCatching { getResource(key) }.getOrNull()
            if(cached != null)
                return getLine(cached, position.line)
        }
-        val cached = cache[position.file]
+        val cached = cache[position.file.lowercase()]
        if(cached != null)
            return getLine(cached, position.line)
        val path = Path(position.file).sanitize()
-        val cached2 = cache[path.toString()]
+        val cached2 = cache[path.toString().lowercase()]
        if(cached2 != null)
            return getLine(cached2, position.line)
        throw NoSuchElementException("cannot get source line $position, with path $path")
    }

    private fun getLine(code: SourceCode, lineIndex: Int): String {
-        var spans = lineSpanCache[code]
-        if(spans==null) {
+        val spans = lineSpanCache.computeIfAbsent(code) {
            val lineSpans = Regex("^", RegexOption.MULTILINE).findAll(code.text).map { it.range.first }
            val ends = lineSpans.drop(1) + code.text.length
-            spans = lineSpans.zip(ends).map { (start, end) -> LineSpan(start, end) }.toList().toTypedArray()
-            lineSpanCache[code] = spans
+            lineSpans.zip(ends).map { (start, end) -> LineSpan(start, end) }.toList().toTypedArray()
        }
        val span = spans[lineIndex - 1]
        return code.text.substring(span.start, span.end).trim()
@@ -69,6 +71,6 @@ object ImportFileSystem {

    private class LineSpan(val start: Int, val end: Int)

-    private val cache = TreeMap<String, SourceCode>(String.CASE_INSENSITIVE_ORDER)
-    private val lineSpanCache = mutableMapOf<SourceCode, Array<LineSpan>>()
-}
+    private val cache = ConcurrentHashMap<String, SourceCode>()
+    private val lineSpanCache = ConcurrentHashMap<SourceCode, Array<LineSpan>>()
+}
@@ -11,11 +11,13 @@ class C128Target: ICompilationTarget,
    IMemSizer by NormalMemSizer(Mflpt5.FLOAT_MEM_SIZE) {

    override val name = NAME
+    override val supportsBankedCalls = true
    override val defaultEncoding = Encoding.PETSCII
    override val libraryPath = null
    override val customLauncher = emptyList<String>()
    override val additionalAssemblerOptions = emptyList<String>()
    override val defaultOutputType = OutputType.PRG
+    override val defaultLauncherType = CbmPrgLauncherType.BASIC

    companion object {
        const val NAME = "c128"
@@ -26,18 +28,16 @@ class C128Target: ICompilationTarget,

    override val FLOAT_MAX_POSITIVE = Mflpt5.FLOAT_MAX_POSITIVE
    override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
-    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
-    override val STARTUP_CODE_RESERVED_SIZE = 20u
+    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE.toUInt()
    override val PROGRAM_LOAD_ADDRESS = 0x1c01u
    override val PROGRAM_MEMTOP_ADDRESS = 0xc000u

-    override val BSSHIGHRAM_START = 0u    // TODO address?
-    override val BSSHIGHRAM_END = 0u      // TODO address?
-    override val BSSGOLDENRAM_START = 0u  // TODO address?
-    override val BSSGOLDENRAM_END = 0u    // TODO address?
+    override val BSSHIGHRAM_START = 0u      // no high ram
+    override val BSSHIGHRAM_END = 0u        // no high ram
+    override val BSSGOLDENRAM_START = 0x1300u
+    override val BSSGOLDENRAM_END = 0x1bdfu     //  note: $1be0 - $1bff contains the 16 virtual registers

    override lateinit var zeropage: Zeropage
-    override lateinit var golden: GoldenRam

    override fun getFloatAsmBytes(num: Number) = Mflpt5.fromNumber(num).makeFloatFillAsm()

@@ -71,11 +71,10 @@ class C128Target: ICompilationTarget,
        process.waitFor()
    }

-    override fun isIOAddress(address: UInt): Boolean = address==0u || address==1u || address in 0xd000u..0xdfffu
+    override fun isIOAddress(address: UInt): Boolean = address==0u || address==1u || address in 0xd000u..0xdfffu || address in 0xff00u..0xff04u

    override fun initializeMemoryAreas(compilerOptions: CompilationOptions) {
        zeropage = C128Zeropage(compilerOptions)
-        golden = GoldenRam(compilerOptions, UIntRange.EMPTY)    // TODO does the c128 have some of this somewhere?
    }

 }
@@ -12,11 +12,13 @@ class C64Target: ICompilationTarget,
    IMemSizer by NormalMemSizer(Mflpt5.FLOAT_MEM_SIZE) {

    override val name = NAME
+    override val supportsBankedCalls = true
    override val defaultEncoding = Encoding.PETSCII
    override val libraryPath = null
    override val customLauncher = emptyList<String>()
    override val additionalAssemblerOptions = emptyList<String>()
    override val defaultOutputType = OutputType.PRG
+    override val defaultLauncherType = CbmPrgLauncherType.BASIC

    companion object {
        const val NAME = "c64"
@@ -29,8 +31,7 @@ class C64Target: ICompilationTarget,

    override val FLOAT_MAX_POSITIVE = Mflpt5.FLOAT_MAX_POSITIVE
    override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
-    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
-    override val STARTUP_CODE_RESERVED_SIZE = 20u
+    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE.toUInt()
    override val PROGRAM_LOAD_ADDRESS = 0x0801u
    override val PROGRAM_MEMTOP_ADDRESS = 0xcfe0u      // $a000  if floats are used
    // note that at $cfe0-$cfff are the 16 'virtual registers' R0-R15
@@ -41,7 +42,6 @@ class C64Target: ICompilationTarget,
    override val BSSGOLDENRAM_END = 0u

    override lateinit var zeropage: Zeropage
-    override lateinit var golden: GoldenRam

    override fun getFloatAsmBytes(num: Number) = Mflpt5.fromNumber(num).makeFloatFillAsm()

@@ -87,7 +87,6 @@ class C64Target: ICompilationTarget,

    override fun initializeMemoryAreas(compilerOptions: CompilationOptions) {
        zeropage = C64Zeropage(compilerOptions)
-        golden = GoldenRam(compilerOptions, UIntRange.EMPTY)
    }

 }
@@ -15,16 +15,17 @@ import kotlin.io.path.nameWithoutExtension

 class ConfigFileTarget(
    override val name: String,
+    override val supportsBankedCalls: Boolean,
    override val defaultEncoding: Encoding,
    override val cpu: CpuType,
    override val PROGRAM_LOAD_ADDRESS: UInt,
    override val PROGRAM_MEMTOP_ADDRESS: UInt,
-    override val STARTUP_CODE_RESERVED_SIZE: UInt,
    override val BSSHIGHRAM_START: UInt,
    override val BSSHIGHRAM_END: UInt,
    override val BSSGOLDENRAM_START: UInt,
    override val BSSGOLDENRAM_END: UInt,
    override val defaultOutputType: OutputType,
+    override val defaultLauncherType: CbmPrgLauncherType,
    override val libraryPath: Path,
    override val customLauncher: List<String>,
    override val additionalAssemblerOptions: List<String>,
@@ -112,19 +113,26 @@ class ConfigFileTarget(
            val assemblerOptionsStr = props.getProperty("assembler_options", "").trim()
            val outputTypeString = props.getProperty("output_type", "PRG")
            val defaultOutputType = OutputType.valueOf(outputTypeString.uppercase())
+            val launcherString = props.getProperty("launcher", "BASIC")
+            val defaultLauncherType = try {
+                CbmPrgLauncherType.valueOf(launcherString.uppercase())
+            } catch (_: IllegalArgumentException) {
+                CbmPrgLauncherType.BASIC
+            }

            return ConfigFileTarget(
                configfile.nameWithoutExtension,
+                props.getProperty("supports_banked_calls", "false").toBoolean(),
                Encoding.entries.first { it.prefix==props.getString("encoding") },
                cpuType,
                props.getInteger("load_address"),
                props.getInteger("memtop"),
-                0u,         // used only in a very specific error condition check in a certain scenario...
                props.getInteger("bss_highram_start"),
                props.getInteger("bss_highram_end"),
                props.getInteger("bss_goldenram_start"),
                props.getInteger("bss_goldenram_end"),
                defaultOutputType,
+                defaultLauncherType,
                libraryPath,
                customLauncher,
                if(assemblerOptionsStr=="") emptyList() else assemblerOptionsStr.split(" "),
@@ -145,10 +153,9 @@ class ConfigFileTarget(
    // TODO floats are not yet supported here, just enter some values
    override val FLOAT_MAX_POSITIVE = 9.999999999e97
    override val FLOAT_MAX_NEGATIVE = -9.999999999e97
-    override val FLOAT_MEM_SIZE = 8
+    override val FLOAT_MEM_SIZE = 8u

    override lateinit var zeropage: Zeropage
-    override lateinit var golden: GoldenRam     // TODO this is not yet used

    override fun getFloatAsmBytes(num: Number) = TODO("floats")
    override fun convertFloatToBytes(num: Double): List<UByte> = TODO("floats")
@@ -168,6 +175,5 @@ class ConfigFileTarget(
            zpFullsafe,
            compilerOptions
        )
-        // note: there's no golden ram yet
    }
 }
@@ -11,11 +11,13 @@ class Cx16Target: ICompilationTarget,
    IMemSizer by NormalMemSizer(Mflpt5.FLOAT_MEM_SIZE) {

    override val name = NAME
+    override val supportsBankedCalls = true
    override val defaultEncoding = Encoding.PETSCII
    override val libraryPath = null
    override val customLauncher = emptyList<String>()
    override val additionalAssemblerOptions = emptyList<String>()
    override val defaultOutputType = OutputType.PRG
+    override val defaultLauncherType = CbmPrgLauncherType.BASIC

    companion object {
        const val NAME = "cx16"
@@ -26,8 +28,7 @@ class Cx16Target: ICompilationTarget,

    override val FLOAT_MAX_POSITIVE = Mflpt5.FLOAT_MAX_POSITIVE
    override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
-    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
-    override val STARTUP_CODE_RESERVED_SIZE = 20u
+    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE.toUInt()
    override val PROGRAM_LOAD_ADDRESS = 0x0801u
    override val PROGRAM_MEMTOP_ADDRESS = 0x9f00u

@@ -37,7 +38,6 @@ class Cx16Target: ICompilationTarget,
    override val BSSGOLDENRAM_END = 0x07ffu

    override lateinit var zeropage: Zeropage
-    override lateinit var golden: GoldenRam

    override fun getFloatAsmBytes(num: Number) = Mflpt5.fromNumber(num).makeFloatFillAsm()

@@ -87,7 +87,6 @@ class Cx16Target: ICompilationTarget,

    override fun initializeMemoryAreas(compilerOptions: CompilationOptions) {
        zeropage = CX16Zeropage(compilerOptions)
-        golden = GoldenRam(compilerOptions, BSSGOLDENRAM_START..BSSGOLDENRAM_END)
    }


@@ -19,7 +19,7 @@ data class Mflpt5(val b0: UByte, val b1: UByte, val b2: UByte, val b3: UByte, va

            val flt = num.toDouble()
            if (flt !in FLOAT_MAX_NEGATIVE..FLOAT_MAX_POSITIVE)
-                throw InternalCompilerException("floating point number out of 5-byte mflpt range: $this")
+                throw InternalCompilerException("floating point number out of 5-byte mflpt range: $flt")
            if (flt == 0.0)
                return zero

@@ -40,7 +40,7 @@ data class Mflpt5(val b0: UByte, val b1: UByte, val b2: UByte, val b3: UByte, va

            return when {
                exponent < 0 -> zero  // underflow, use zero instead
-                exponent > 255 -> throw InternalCompilerException("floating point overflow: $this")
+                exponent > 255 -> throw InternalCompilerException("floating point overflow: $flt")
                exponent == 0 -> zero
                else -> {
                    val mantLong = mantissa.toLong()
@@ -30,10 +30,10 @@ internal class NormalMemSizer(val floatsize: Int): IMemSizer {
            dt.isFloat -> floatsize * (numElements ?: 1)
            dt.isLong -> 4 * (numElements ?: 1)
            dt.isPointer -> 2  // pointer is just a uword
-            dt.isStructInstance -> dt.subType!!.memsize(this)
+            dt.isStructInstance -> dt.subType?.memsize(this) ?: 0
            dt.isUndefined -> throw IllegalArgumentException("undefined has no memory size")
            else -> 2 * (numElements ?: 1)
        }
    }

-}
+}
@@ -11,11 +11,13 @@ class PETTarget: ICompilationTarget,
    IMemSizer by NormalMemSizer(Mflpt5.FLOAT_MEM_SIZE) {

    override val name = NAME
+    override val supportsBankedCalls = false
    override val defaultEncoding = Encoding.PETSCII
    override val libraryPath = null
    override val customLauncher = emptyList<String>()
    override val additionalAssemblerOptions = emptyList<String>()
    override val defaultOutputType = OutputType.PRG
+    override val defaultLauncherType = CbmPrgLauncherType.BASIC

    companion object {
        const val NAME = "pet32"
@@ -25,8 +27,7 @@ class PETTarget: ICompilationTarget,

    override val FLOAT_MAX_POSITIVE = Mflpt5.FLOAT_MAX_POSITIVE
    override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
-    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
-    override val STARTUP_CODE_RESERVED_SIZE = 20u
+    override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE.toUInt()
    override val PROGRAM_LOAD_ADDRESS = 0x0401u
    override val PROGRAM_MEMTOP_ADDRESS = 0x8000u

@@ -36,7 +37,6 @@ class PETTarget: ICompilationTarget,
    override val BSSGOLDENRAM_END = 0u

    override lateinit var zeropage: Zeropage
-    override lateinit var golden: GoldenRam

    override fun getFloatAsmBytes(num: Number) = Mflpt5.fromNumber(num).makeFloatFillAsm()

@@ -74,7 +74,6 @@ class PETTarget: ICompilationTarget,

    override fun initializeMemoryAreas(compilerOptions: CompilationOptions) {
        zeropage = PETZeropage(compilerOptions)
-        golden = GoldenRam(compilerOptions, UIntRange.EMPTY)
    }

 }
@@ -13,11 +13,13 @@ class VMTarget: ICompilationTarget,
    IMemSizer by NormalMemSizer(FLOAT_MEM_SIZE) {

    override val name = NAME
+    override val supportsBankedCalls = false
    override val defaultEncoding = Encoding.ISO
    override val libraryPath = null
    override val customLauncher = emptyList<String>()
    override val additionalAssemblerOptions = emptyList<String>()
    override val defaultOutputType = OutputType.PRG
+    override val defaultLauncherType = CbmPrgLauncherType.BASIC

    companion object {
        const val NAME = "virtual"
@@ -28,8 +30,7 @@ class VMTarget: ICompilationTarget,

    override val FLOAT_MAX_POSITIVE = Double.MAX_VALUE
    override val FLOAT_MAX_NEGATIVE = -Double.MAX_VALUE
-    override val FLOAT_MEM_SIZE = VMTarget.FLOAT_MEM_SIZE
-    override val STARTUP_CODE_RESERVED_SIZE = 0u  // not actually used
+    override val FLOAT_MEM_SIZE = VMTarget.FLOAT_MEM_SIZE.toUInt()
    override val PROGRAM_LOAD_ADDRESS = 0u      // not actually used
    override val PROGRAM_MEMTOP_ADDRESS = 0xffffu  // not actually used

@@ -38,7 +39,6 @@ class VMTarget: ICompilationTarget,
    override val BSSGOLDENRAM_START = 0u        // not actually used
    override val BSSGOLDENRAM_END = 0u          // not actually used
    override lateinit var zeropage: Zeropage    // not actually used
-    override lateinit var golden: GoldenRam     // not actually used

    override fun getFloatAsmBytes(num: Number): String {
        // little endian binary representation
@@ -69,6 +69,10 @@ class VMTarget: ICompilationTarget,
    }

    override fun launchEmulator(selectedEmulator: Int, programNameWithPath: Path, quiet: Boolean) {
+        launchEmulatorWithTrace(programNameWithPath, quiet, traceEnabled = false)
+    }
+
+    fun launchEmulatorWithTrace(programNameWithPath: Path, quiet: Boolean, traceEnabled: Boolean) {
        if(!quiet)
            println("\nStarting Virtual Machine...")

@@ -76,7 +80,7 @@ class VMTarget: ICompilationTarget,
        val vm = Class.forName("prog8.vm.VmRunner").getDeclaredConstructor().newInstance() as IVirtualMachineRunner
        val withExt = if(programNameWithPath.extension=="p8ir") programNameWithPath else programNameWithPath.resolveSibling("${programNameWithPath.name}.p8ir")
        if(withExt.isReadable())
-            vm.runProgram(withExt.readText(), quiet)
+            vm.runProgram(withExt.readText(), quiet, traceEnabled)
        else
            throw java.nio.file.NoSuchFileException(withExt.name, null, "not a .p8ir file")
    }
@@ -85,14 +89,13 @@ class VMTarget: ICompilationTarget,

    override fun initializeMemoryAreas(compilerOptions: CompilationOptions) {
        zeropage = VirtualZeropage(compilerOptions)
-        golden = GoldenRam(compilerOptions, UIntRange.EMPTY)
    }
 }



 interface IVirtualMachineRunner {
-    fun runProgram(irSource: String, quiet: Boolean)
+    fun runProgram(irSource: String, quiet: Boolean, traceEnabled: Boolean = false)
 }

 private class VirtualZeropage(options: CompilationOptions): Zeropage(options) {
@@ -8,7 +8,7 @@ import java.io.CharConversionException
 object PetsciiEncoding {

    // decoding:  from Petscii/Screencodes (0-255) to Unicode
-    // character tables used from https://github.com/irmen/cbmcodecs2
+    // character tables used from https://codeberg.org/irmen/cbmcodecs2.git

    private val decodingPetsciiLowercase = charArrayOf(
        '\u0000',    //       0x00 -> \u0000
@@ -1,9 +1,6 @@
 package prog8.code.target.zp

-import prog8.code.core.CompilationOptions
-import prog8.code.core.InternalCompilerException
-import prog8.code.core.Zeropage
-import prog8.code.core.ZeropageType
+import prog8.code.core.*


 // reference: "Mapping the C128" zeropage chapter.
@@ -46,13 +43,13 @@ class C128Zeropage(options: CompilationOptions) : Zeropage(options) {
                    0xb0u, 0xb1u, 0xb4u, 0xb5u, 0xb6u
                ))

-                // if(options.zeropage==ZeropageType.BASICSAFE) {
-                    // can also clobber the FP locations (unconditionally, because the C128 target doesn't support floating point calculations in prog8 at this time0
-                    free.addAll(arrayOf(0x14u, 0x28u, 0x29u, 0x2au, 0x2bu, 0x2cu,
-                        0x50u, 0x51u, 0x52u, 0x53u, 0x54u, 0x59u, 0x5au, 0x5bu, 0x5cu, 0x5du, 0x5eu, 0x5fu, 0x60u, 0x61u, 0x62u,
-                        0x63u, 0x64u, 0x65u, 0x66u, 0x67u, 0x68u,
-                        0x6au, 0x6bu, 0x6cu, 0x6du, 0x6eu, 0x6fu, 0x71u))
-                // }
+                // C128 doesn't support floating point calculations in Prog8, so we can use the FP zeropage locations
+                // for general variables in both BASICSAFE and FLOATSAFE modes.
+                // These addresses are normally used by the C128 BASIC floating point routines.
+                free.addAll(arrayOf(0x14u, 0x28u, 0x29u, 0x2au, 0x2bu, 0x2cu,
+                    0x50u, 0x51u, 0x52u, 0x53u, 0x54u, 0x59u, 0x5au, 0x5bu, 0x5cu, 0x5du, 0x5eu, 0x5fu, 0x60u, 0x61u, 0x62u,
+                    0x63u, 0x64u, 0x65u, 0x66u, 0x67u, 0x68u,
+                    0x6au, 0x6bu, 0x6cu, 0x6du, 0x6eu, 0x6fu, 0x71u))
            }
            ZeropageType.DONTUSE -> {
                free.clear()  // don't use zeropage at all
@@ -64,6 +61,43 @@ class C128Zeropage(options: CompilationOptions) : Zeropage(options) {
        free.addAll(distinctFree)

        removeReservedFromFreePool()
+
+        if(options.zeropage==ZeropageType.FULL || options.zeropage==ZeropageType.KERNALSAFE) {
+            // C128 DESIGN: Virtual registers are ONLY allocated when sufficient zeropage space exists.
+            // C128 has limited zeropage space in BASICSAFE/FLOATSAFE modes.
+            // Virtual registers are only allocated in FULL and KERNALSAFE modes where space permits.
+            allocateCx16VirtualRegisters()
+        }
+        
        retainAllowed()
    }
+
+    private fun allocateCx16VirtualRegisters() {
+        // Note: the 16 virtual registers R0-R15 are not regular allocated variables, they're *memory mapped* elsewhere to fixed addresses.
+        // However, to be able for the compiler to "see" them as zeropage variables, we have to register them here as well.
+        // This is important because the compiler sometimes treats ZP variables more efficiently (for example if it's a pointer)
+        val base = 0x0a     // Unfortunately it cannot be the same as on the Commander X16 ($02).
+        for(reg in 0..15) {
+            allocatedVariables["cx16.r${reg}"]   = VarAllocation((base+reg*2).toUInt(), DataType.UWORD, 2)       // cx16.r0 .. cx16.r15
+            allocatedVariables["cx16.r${reg}s"]  = VarAllocation((base+reg*2).toUInt(), DataType.WORD, 2)        // cx16.r0s .. cx16.r15s
+            allocatedVariables["cx16.r${reg}L"]  = VarAllocation((base+reg*2).toUInt(), DataType.UBYTE, 1)       // cx16.r0L .. cx16.r15L
+            allocatedVariables["cx16.r${reg}H"]  = VarAllocation((base+1+reg*2).toUInt(), DataType.UBYTE, 1)     // cx16.r0H .. cx16.r15H
+            allocatedVariables["cx16.r${reg}sL"] = VarAllocation((base+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sL .. cx16.r15sL
+            allocatedVariables["cx16.r${reg}sH"] = VarAllocation((base+1+reg*2).toUInt(), DataType.BYTE, 1)      // cx16.r0sH .. cx16.r15sH
+            allocatedVariables["cx16.r${reg}bL"] = VarAllocation((base+reg*2).toUInt(), DataType.BOOL, 1)        // cx16.r0bL .. cx16.r15bL
+            allocatedVariables["cx16.r${reg}bH"] = VarAllocation((base+1+reg*2).toUInt(), DataType.BOOL, 1)      // cx16.r0bH .. cx16.r15bH
+            free.remove((base+reg*2).toUInt())
+            free.remove((base+1+reg*2).toUInt())
+        }
+
+        // 32 bits combined register pairs cx16.r0r1 .. cx16.r14r15
+        allocatedVariables["cx16.r0r1sl"]   = VarAllocation((base+0*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r2r3sl"]   = VarAllocation((base+1*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r4r5sl"]   = VarAllocation((base+2*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r6r7sl"]   = VarAllocation((base+3*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r8r9sl"]   = VarAllocation((base+4*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r10r11sl"] = VarAllocation((base+5*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r12r13sl"] = VarAllocation((base+6*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r14r15sl"] = VarAllocation((base+7*4).toUInt(), DataType.LONG, 4)
+    }
 }
@@ -9,7 +9,7 @@ class C64Zeropage(options: CompilationOptions) : Zeropage(options) {
    override val SCRATCH_REG = 0x03u     // temp storage for a register byte, must be B1+1
    override val SCRATCH_W1 = 0xfbu      // temp storage 1 for a word  $fb+$fc
    override val SCRATCH_W2 = 0xfdu      // temp storage 2 for a word  $fd+$fe
-    override val SCRATCH_PTR = 0x9bu     // temp storage for a pointer $9b+$9c
+    override val SCRATCH_PTR = 0x04u     // temp storage for a pointer $04+$05


    init {
@@ -57,7 +57,7 @@ class C64Zeropage(options: CompilationOptions) : Zeropage(options) {
                // add the free Zp addresses
                // these are valid for the C-64 but allow BASIC to keep running fully *as long as you don't use tape I/O*
                free.addAll(arrayOf(0x02, 0x03, 0x04, 0x05, 0x06, 0x0a, 0x0e,
-                        0x92, 0x96, 0x9b, 0x9c, 0x9e, 0x9f, 0xa6,
+                        0x92, 0x96, 0x9c, 0x9e, 0x9f, 0xa6,
                        0xb0, 0xb1, 0xbe, 0xbf, 0xf9).map{it.toUInt()})
            } else {
                // don't use the zeropage at all
@@ -72,7 +72,10 @@ class C64Zeropage(options: CompilationOptions) : Zeropage(options) {
        removeReservedFromFreePool()

        if(options.zeropage==ZeropageType.FULL || options.zeropage==ZeropageType.KERNALSAFE) {
-            // in these cases there is enough space on the zero page to stick the cx16 virtual registers in there as well.
+            // C64 DESIGN: Virtual registers are ONLY allocated when sufficient zeropage space exists.
+            // C64 has limited zeropage space compared to CX16. In BASICSAFE and FLOATSAFE modes,
+            // there isn't enough contiguous space for all 32 bytes of virtual register variants.
+            // Virtual registers are only allocated in FULL and KERNALSAFE modes where space permits.
            allocateCx16VirtualRegisters()
        }

@@ -83,16 +86,28 @@ class C64Zeropage(options: CompilationOptions) : Zeropage(options) {
        // Note: the 16 virtual registers R0-R15 are not regular allocated variables, they're *memory mapped* elsewhere to fixed addresses.
        // However, to be able for the compiler to "see" them as zeropage variables, we have to register them here as well.
        // This is important because the compiler sometimes treats ZP variables more efficiently (for example if it's a pointer)
-        // The base addres is $04.  Unfortunately it cannot be the same as on the Commander X16 ($02).
+        val base = 0x04     // Unfortunately it cannot be the same as on the Commander X16 ($02).
        for(reg in 0..15) {
-            allocatedVariables["cx16.r${reg}"]   = VarAllocation((4+reg*2).toUInt(), DataType.UWORD, 2)       // cx16.r0 .. cx16.r15
-            allocatedVariables["cx16.r${reg}s"]  = VarAllocation((4+reg*2).toUInt(), DataType.WORD, 2)        // cx16.r0s .. cx16.r15s
-            allocatedVariables["cx16.r${reg}L"]  = VarAllocation((4+reg*2).toUInt(), DataType.UBYTE, 1)       // cx16.r0L .. cx16.r15L
-            allocatedVariables["cx16.r${reg}H"]  = VarAllocation((5+reg*2).toUInt(), DataType.UBYTE, 1)       // cx16.r0H .. cx16.r15H
-            allocatedVariables["cx16.r${reg}sL"] = VarAllocation((4+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sL .. cx16.r15sL
-            allocatedVariables["cx16.r${reg}sH"] = VarAllocation((5+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sH .. cx16.r15sH
-            free.remove((4+reg*2).toUInt())
-            free.remove((5+reg*2).toUInt())
+            allocatedVariables["cx16.r${reg}"]   = VarAllocation((base+reg*2).toUInt(), DataType.UWORD, 2)       // cx16.r0 .. cx16.r15
+            allocatedVariables["cx16.r${reg}s"]  = VarAllocation((base+reg*2).toUInt(), DataType.WORD, 2)        // cx16.r0s .. cx16.r15s
+            allocatedVariables["cx16.r${reg}L"]  = VarAllocation((base+reg*2).toUInt(), DataType.UBYTE, 1)       // cx16.r0L .. cx16.r15L
+            allocatedVariables["cx16.r${reg}H"]  = VarAllocation((base+1+reg*2).toUInt(), DataType.UBYTE, 1)     // cx16.r0H .. cx16.r15H
+            allocatedVariables["cx16.r${reg}sL"] = VarAllocation((base+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sL .. cx16.r15sL
+            allocatedVariables["cx16.r${reg}sH"] = VarAllocation((base+1+reg*2).toUInt(), DataType.BYTE, 1)      // cx16.r0sH .. cx16.r15sH
+            allocatedVariables["cx16.r${reg}bL"] = VarAllocation((base+reg*2).toUInt(), DataType.BOOL, 1)        // cx16.r0bL .. cx16.r15bL
+            allocatedVariables["cx16.r${reg}bH"] = VarAllocation((base+1+reg*2).toUInt(), DataType.BOOL, 1)      // cx16.r0bH .. cx16.r15bH
+            free.remove((base+reg*2).toUInt())
+            free.remove((base+1+reg*2).toUInt())
        }
+
+        // 32 bits combined register pairs cx16.r0r1 .. cx16.r14r15
+        allocatedVariables["cx16.r0r1sl"]   = VarAllocation((base+0*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r2r3sl"]   = VarAllocation((base+1*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r4r5sl"]   = VarAllocation((base+2*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r6r7sl"]   = VarAllocation((base+3*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r8r9sl"]   = VarAllocation((base+4*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r10r11sl"] = VarAllocation((base+5*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r12r13sl"] = VarAllocation((base+6*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r14r15sl"] = VarAllocation((base+7*4).toUInt(), DataType.LONG, 4)
    }
 }
@@ -22,41 +22,47 @@ class CX16Zeropage(options: CompilationOptions) : Zeropage(options) {

        // the addresses 0x02 to 0x21 (inclusive) are taken for sixteen virtual 16-bit api registers.

-        synchronized(this) {
-            when (options.zeropage) {
-                ZeropageType.FULL -> {
-                    free.addAll(0x22u..0xffu)
-                }
-                ZeropageType.KERNALSAFE -> {
-                    free.addAll(0x22u..0x7fu)
-                    free.addAll(0xa9u..0xffu)
-                }
-                ZeropageType.FLOATSAFE -> {
-                    free.addAll(0x22u..0x7fu)
-                    free.addAll(0xd4u..0xffu)
-                }
-                ZeropageType.BASICSAFE -> {
-                    free.addAll(0x22u..0x7fu)
-                }
-                ZeropageType.DONTUSE -> {
-                    free.clear() // don't use zeropage at all
-                }
+        // Initialize free list - no synchronization needed during construction
+        // (object reference doesn't escape until fully constructed)
+        when (options.zeropage) {
+            ZeropageType.FULL -> {
+                free.addAll(0x22u..0xffu)
+            }
+            ZeropageType.KERNALSAFE -> {
+                free.addAll(0x22u..0x7fu)
+                free.addAll(0xa9u..0xffu)
+            }
+            ZeropageType.FLOATSAFE -> {
+                free.addAll(0x22u..0x7fu)
+                free.addAll(0xd4u..0xffu)
+            }
+            ZeropageType.BASICSAFE -> {
+                free.addAll(0x22u..0x7fu)
+            }
+            ZeropageType.DONTUSE -> {
+                free.clear() // don't use zeropage at all
            }
-
-            val distinctFree = free.distinct()
-            free.clear()
-            free.addAll(distinctFree)
-
-            removeReservedFromFreePool()
-            allocateCx16VirtualRegisters()
-            retainAllowed()
        }
+
+        val distinctFree = free.distinct()
+        free.clear()
+        free.addAll(distinctFree)
+
+        removeReservedFromFreePool()
+        allocateCx16VirtualRegisters()
+        retainAllowed()
    }

    private fun allocateCx16VirtualRegisters() {
-        // Note: the 16 virtual registers R0-R15 are not regular allocated variables, they're *memory mapped* elsewhere to fixed addresses.
-        // However, to be able for the compiler to "see" them as zeropage variables, we have to register them here as well.
-        // This is important because the compiler sometimes treats ZP variables more efficiently (for example if it's a pointer)
+        // CX16 DESIGN: Virtual registers are ALWAYS allocated in zeropage for all ZeropageType modes.
+        // The Commander X16 has ample zeropage space (0x22-0x7F in BASICSAFE, up to 0x22-0xFF in FULL),
+        // so virtual registers can always fit. This ensures consistent behavior across all modes.
+        // Virtual registers occupy addresses 0x02-0x21 (32 bytes for r0-r15 variants).
+        //
+        // Note: the 16 virtual registers R0-R15 are not regular allocated variables, they're *memory mapped*
+        // elsewhere to fixed addresses. However, to be able for the compiler to "see" them as zeropage
+        // variables, we have to register them here as well. This is important because the compiler
+        // sometimes treats ZP variables more efficiently (for example if it's a pointer).
        for(reg in 0..15) {
            allocatedVariables["cx16.r${reg}"]   = VarAllocation((2+reg*2).toUInt(), DataType.UWORD, 2)       // cx16.r0 .. cx16.r15
            allocatedVariables["cx16.r${reg}s"]  = VarAllocation((2+reg*2).toUInt(), DataType.WORD, 2)        // cx16.r0s .. cx16.r15s
@@ -64,6 +70,19 @@ class CX16Zeropage(options: CompilationOptions) : Zeropage(options) {
            allocatedVariables["cx16.r${reg}H"]  = VarAllocation((3+reg*2).toUInt(), DataType.UBYTE, 1)       // cx16.r0H .. cx16.r15H
            allocatedVariables["cx16.r${reg}sL"] = VarAllocation((2+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sL .. cx16.r15sL
            allocatedVariables["cx16.r${reg}sH"] = VarAllocation((3+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sH .. cx16.r15sH
+            allocatedVariables["cx16.r${reg}bL"] = VarAllocation((2+reg*2).toUInt(), DataType.BOOL, 1)       // cx16.r0bL .. cx16.r15bL
+            allocatedVariables["cx16.r${reg}bH"] = VarAllocation((3+reg*2).toUInt(), DataType.BOOL, 1)       // cx16.r0bH .. cx16.r15bH
        }
+
+        // 32 bits combined register pairs cx16.r0r1 .. cx16.r14r15
+        allocatedVariables["cx16.r0r1sl"]   = VarAllocation((2+0*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r2r3sl"]   = VarAllocation((2+1*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r4r5sl"]   = VarAllocation((2+2*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r6r7sl"]   = VarAllocation((2+3*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r8r9sl"]   = VarAllocation((2+4*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r10r11sl"] = VarAllocation((2+5*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r12r13sl"] = VarAllocation((2+6*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r14r15sl"] = VarAllocation((2+7*4).toUInt(), DataType.LONG, 4)
+
    }
 }
@@ -57,7 +57,24 @@ class ConfigurableZeropage(
                allocatedVariables["cx16.r${reg}H"]  = VarAllocation(address+1u, DataType.UBYTE, 1)    // cx16.r0H .. cx16.r15H
                allocatedVariables["cx16.r${reg}sL"] = VarAllocation(address, DataType.BYTE, 1)        // cx16.r0sL .. cx16.r15sL
                allocatedVariables["cx16.r${reg}sH"] = VarAllocation(address+1u, DataType.BYTE, 1)     // cx16.r0sH .. cx16.r15sH
+                allocatedVariables["cx16.r${reg}bL"] = VarAllocation(address, DataType.BOOL, 1)        // cx16.r0bL .. cx16.r15bL
+                allocatedVariables["cx16.r${reg}bH"] = VarAllocation(address+1u, DataType.BOOL, 1)     // cx16.r0bH .. cx16.r15bH
+                free.remove(address)
+                free.remove(address+1u)
            }
        }
+
+        if(virtualRegistersStart<0xffu) {
+            // 32 bits combined register pairs cx16.r0r1 .. cx16.r14r15
+            val start = virtualRegistersStart.toInt()
+            allocatedVariables["cx16.r0r1sl"] = VarAllocation((start + 0 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r2r3sl"] = VarAllocation((start + 1 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r4r5sl"] = VarAllocation((start + 2 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r6r7sl"] = VarAllocation((start + 3 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r8r9sl"] = VarAllocation((start + 4 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r10r11sl"] = VarAllocation((start + 5 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r12r13sl"] = VarAllocation((start + 6 * 4).toUInt(), DataType.LONG, 4)
+            allocatedVariables["cx16.r14r15sl"] = VarAllocation((start + 7 * 4).toUInt(), DataType.LONG, 4)
+        }
    }
 }
@@ -1,9 +1,6 @@
 package prog8.code.target.zp

-import prog8.code.core.CompilationOptions
-import prog8.code.core.InternalCompilerException
-import prog8.code.core.Zeropage
-import prog8.code.core.ZeropageType
+import prog8.code.core.*


 // reference: http://www.zimmers.net/cbmpics/cbm/PETx/petmem.txt
@@ -35,7 +32,10 @@ class PETZeropage(options: CompilationOptions) : Zeropage(options) {
            }
            ZeropageType.FLOATSAFE,
            ZeropageType.BASICSAFE -> {
-                free.addAll(0xb1u..0xbau)       // TODO more?
+                // Only scratch register area is safe for transient use.
+                // $b5 and $ba are clobbered by PET BASIC/Kernal calls like CHROUT ($ffd2).
+                // User variables requiring persistent storage must NOT be placed here.
+                free.addAll(listOf(0xb1u, 0xb2u, 0xb3u, 0xb4u, 0xb6u, 0xb7u, 0xb8u, 0xb9u, 0xfbu, 0xfcu, 0xfdu, 0xfeu))
            }
            ZeropageType.DONTUSE -> {
                free.clear()  // don't use zeropage at all
@@ -47,6 +47,43 @@ class PETZeropage(options: CompilationOptions) : Zeropage(options) {
        free.addAll(distinctFree)

        removeReservedFromFreePool()
+
+        if(options.zeropage==ZeropageType.FULL || options.zeropage==ZeropageType.KERNALSAFE) {
+            // PET DESIGN: Virtual registers are ONLY allocated when sufficient zeropage space exists.
+            // PET has very limited zeropage space in BASICSAFE/FLOATSAFE modes (only 0xB1-0xBA).
+            // Virtual registers are only allocated in FULL and KERNALSAFE modes where space permits.
+            allocateCx16VirtualRegisters()
+        }
+
        retainAllowed()
    }
-}
+
+    private fun allocateCx16VirtualRegisters() {
+        // Note: the 16 virtual registers R0-R15 are not regular allocated variables, they're *memory mapped* elsewhere to fixed addresses.
+        // However, to be able for the compiler to "see" them as zeropage variables, we have to register them here as well.
+        // This is important because the compiler sometimes treats ZP variables more efficiently (for example if it's a pointer)
+        val base = 0x04     // Unfortunately it cannot be the same as on the Commander X16 ($02).  TODO: is this valid on PET?
+        for(reg in 0..15) {
+            allocatedVariables["cx16.r${reg}"]   = VarAllocation((base+reg*2).toUInt(), DataType.UWORD, 2)       // cx16.r0 .. cx16.r15
+            allocatedVariables["cx16.r${reg}s"]  = VarAllocation((base+reg*2).toUInt(), DataType.WORD, 2)        // cx16.r0s .. cx16.r15s
+            allocatedVariables["cx16.r${reg}L"]  = VarAllocation((base+reg*2).toUInt(), DataType.UBYTE, 1)       // cx16.r0L .. cx16.r15L
+            allocatedVariables["cx16.r${reg}H"]  = VarAllocation((base+1+reg*2).toUInt(), DataType.UBYTE, 1)     // cx16.r0H .. cx16.r15H
+            allocatedVariables["cx16.r${reg}sL"] = VarAllocation((base+reg*2).toUInt(), DataType.BYTE, 1)        // cx16.r0sL .. cx16.r15sL
+            allocatedVariables["cx16.r${reg}sH"] = VarAllocation((base+1+reg*2).toUInt(), DataType.BYTE, 1)      // cx16.r0sH .. cx16.r15sH
+            allocatedVariables["cx16.r${reg}bL"] = VarAllocation((base+reg*2).toUInt(), DataType.BOOL, 1)        // cx16.r0bL .. cx16.r15bL
+            allocatedVariables["cx16.r${reg}bH"] = VarAllocation((base+1+reg*2).toUInt(), DataType.BOOL, 1)      // cx16.r0bH .. cx16.r15bH
+            free.remove((base+reg*2).toUInt())
+            free.remove((base+1+reg*2).toUInt())
+        }
+
+        // 32 bits combined register pairs cx16.r0r1 .. cx16.r14r15
+        allocatedVariables["cx16.r0r1sl"]   = VarAllocation((base+0*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r2r3sl"]   = VarAllocation((base+1*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r4r5sl"]   = VarAllocation((base+2*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r6r7sl"]   = VarAllocation((base+3*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r8r9sl"]   = VarAllocation((base+4*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r10r11sl"] = VarAllocation((base+5*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r12r13sl"] = VarAllocation((base+6*4).toUInt(), DataType.LONG, 4)
+        allocatedVariables["cx16.r14r15sl"] = VarAllocation((base+7*4).toUInt(), DataType.LONG, 4)
+    }
+}
@@ -0,0 +1,67 @@
+package prog8tests.helpers
+
+import prog8.code.core.*
+
+
+/**
+ * Dummy IMemSizer implementation for testing.
+ * Returns standard memory sizes for all data types.
+ */
+object DummyMemsizer : IMemSizer {
+    override fun memorySize(dt: DataType, numElements: Int?): Int {
+        if (dt.isPointerArray)
+            return 2 * numElements!!
+        else if (dt.isArray) {
+            require(numElements != null)
+            return when (dt.sub) {
+                BaseDataType.BOOL, BaseDataType.BYTE, BaseDataType.UBYTE -> numElements
+                BaseDataType.UWORD, BaseDataType.WORD -> numElements * 2
+                BaseDataType.LONG -> numElements * 4
+                BaseDataType.FLOAT -> numElements * 5
+                else -> throw IllegalArgumentException("invalid sub type")
+            }
+        }
+        return when {
+            dt.isByteOrBool -> 1 * (numElements ?: 1)
+            dt.isLong -> 4 * (numElements ?: 1)
+            dt.isFloat -> 5 * (numElements ?: 1)
+            else -> 2 * (numElements ?: 1)
+        }
+    }
+
+    override fun memorySize(dt: BaseDataType): Int {
+        return memorySize(DataType.forDt(dt), null)
+    }
+}
+
+
+/**
+ * Dummy IStringEncoding implementation for testing.
+ * Returns empty list/string for all operations.
+ */
+object DummyStringEncoder : IStringEncoding {
+    override val defaultEncoding: Encoding = Encoding.ISO
+
+    override fun encodeString(str: String, encoding: Encoding): List<UByte> {
+        return emptyList()
+    }
+
+    override fun decodeString(bytes: Iterable<UByte>, encoding: Encoding): String {
+        return ""
+    }
+}
+
+
+/**
+ * ASCII IStringEncoding implementation for testing.
+ * Encodes/decodes using simple ASCII mapping.
+ */
+object AsciiStringEncoder : IStringEncoding {
+    override val defaultEncoding: Encoding = Encoding.ISO
+
+    override fun encodeString(str: String, encoding: Encoding): List<UByte> =
+        str.map { it.code.toUByte() }
+
+    override fun decodeString(bytes: Iterable<UByte>, encoding: Encoding): String =
+        bytes.joinToString("") { it.toInt().toChar().toString() }
+}
@@ -3,45 +3,61 @@ package prog8tests.helpers
 import prog8.code.core.IErrorReporter
 import prog8.code.core.Position

-internal class ErrorReporterForTests(private val throwExceptionAtReportIfErrors: Boolean=true, private val keepMessagesAfterReporting: Boolean=false): IErrorReporter {
+
+/**
+ * Test implementation of IErrorReporter that collects errors/warnings/infos in memory.
+ * 
+ * @param throwExceptionAtReportIfErrors If true, report() will throw an exception when errors exist
+ * @param keepMessagesAfterReporting If false, clear() is called after report()
+ */
+class ErrorReporterForTests(
+    private val throwExceptionAtReportIfErrors: Boolean = true,
+    private val keepMessagesAfterReporting: Boolean = false
+) : IErrorReporter {

    val errors = mutableListOf<String>()
    val warnings = mutableListOf<String>()
    val infos = mutableListOf<String>()
+    val printedErrors = mutableListOf<String>()

    override fun err(msg: String, position: Position) {
        val text = "${position.toClickableStr()} $msg"
-        if(text !in errors)
+        if (text !in errors)
            errors.add(text)
    }

    override fun warn(msg: String, position: Position) {
        val text = "${position.toClickableStr()} $msg"
-        if(text !in warnings)
+        if (text !in warnings)
            warnings.add(text)
    }

    override fun info(msg: String, position: Position) {
        val text = "${position.toClickableStr()} $msg"
-        if(text !in infos)
+        if (text !in infos)
            infos.add(text)
    }

-    override fun undefined(symbol: List<String>, position: Position) {
+    override fun undefined(symbol: List<String>, suggestImport: Boolean, position: Position) {
        err("undefined symbol: ${symbol.joinToString(".")}", position)
    }

-    override fun noErrors(): Boolean  = errors.isEmpty()
-    override fun noErrorForLine(position: Position) = !errors.any { ":${position.line}:" in it }
-    override fun printSingleError(errormessage: String) { /* prints nothing in tests */ }
+    override fun noErrors(): Boolean = errors.isEmpty()
+    
+    override fun noErrorForLine(position: Position): Boolean =
+        !errors.any { ":${position.line}:" in it }
+    
+    override fun printSingleError(errormessage: String) {
+        printedErrors.add(errormessage)
+    }

    override fun report() {
        infos.forEach { println("UNITTEST COMPILATION REPORT: INFO: $it") }
        warnings.forEach { println("UNITTEST COMPILATION REPORT: WARNING: $it") }
        errors.forEach { println("UNITTEST COMPILATION REPORT: ERROR: $it") }
-        if(throwExceptionAtReportIfErrors)
+        if (throwExceptionAtReportIfErrors)
            finalizeNumErrors(errors.size, warnings.size, infos.size)
-        if(!keepMessagesAfterReporting) {
+        if (!keepMessagesAfterReporting) {
            clear()
        }
    }
@@ -0,0 +1,109 @@
+package prog8tests.codecore
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import prog8.code.core.escape
+import prog8.code.core.toHex
+import prog8.code.core.unescape
+
+/**
+ * Unit tests for conversion functions in codeCore.
+ * Focus on toHex boundaries and escape/unescape roundtrips.
+ */
+class TestConversions: FunSpec({
+
+    // ============================================================================
+    // toHex() Tests
+    // ============================================================================
+
+    test("toHex for 0-15 (decimal output)") {
+        0.toHex() shouldBe "0"
+        10.toHex() shouldBe "10"
+        15.toHex() shouldBe "15"
+    }
+
+    test("toHex for 16-255 (hex with $)") {
+        16.toHex() shouldBe "\$10"
+        255.toHex() shouldBe "\$ff"
+    }
+
+    test("toHex for 256-65535 (4 digit hex)") {
+        256.toHex() shouldBe "\$0100"
+        65535.toHex() shouldBe "\$ffff"
+    }
+
+    test("toHex for larger numbers (8 digit hex)") {
+        65536.toHex() shouldBe "\$00010000"
+        0x12345678.toHex() shouldBe "\$12345678"
+    }
+
+    test("toHex for negative numbers") {
+        (-1).toHex() shouldBe "-1"
+        (-255).toHex() shouldBe "-\$ff"
+        Int.MIN_VALUE.toHex() shouldBe "\$80000000"
+    }
+
+    test("UInt.toHex") {
+        0u.toHex() shouldBe "0"
+        15u.toHex() shouldBe "15"
+        255u.toHex() shouldBe "\$ff"
+        65535u.toHex() shouldBe "\$ffff"
+    }
+
+    // ============================================================================
+    // escape() Tests
+    // ============================================================================
+
+    test("escape for plain string") {
+        "hello".escape() shouldBe "hello"
+    }
+
+    test("escape for tab and newline") {
+        "hello\tworld".escape() shouldBe "hello\\tworld"
+        "hello\nworld".escape() shouldBe "hello\\nworld"
+    }
+
+    test("escape for double quote") {
+        "hello\"world".escape() shouldBe "hello\\\"world"
+    }
+
+    test("escape for unicode outside passthrough range") {
+        "€".escape() shouldBe "\\u20ac"
+    }
+
+    test("escape for passthrough characters (\\u8000-\\u80ff)") {
+        "\u8000".escape() shouldBe "\\x00"
+        "\u80ff".escape() shouldBe "\\xff"
+    }
+
+    // ============================================================================
+    // unescape() Tests
+    // ============================================================================
+
+    test("unescape for plain string") {
+        "hello".unescape() shouldBe "hello"
+    }
+
+    test("unescape for tab and newline") {
+        "hello\\tworld".unescape() shouldBe "hello\tworld"
+        "hello\\nworld".unescape() shouldBe "hello\nworld"
+    }
+
+    test("unescape for double quote") {
+        "hello\\\"world".unescape() shouldBe "hello\"world"
+    }
+
+    test("unescape for unicode") {
+        "\\u0041".unescape() shouldBe "A"
+        "\\u20ac".unescape() shouldBe "€"
+    }
+
+    // ============================================================================
+    // Roundtrip Tests
+    // ============================================================================
+
+    test("escape then unescape roundtrip") {
+        val original = "hello\t\nworld\"test"
+        original.escape().unescape() shouldBe original
+    }
+})
@@ -0,0 +1,311 @@
+package prog8tests.codecore
+
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.booleans.shouldBeFalse
+import io.kotest.matchers.booleans.shouldBeTrue
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+import prog8.code.core.*
+
+/**
+ * Unit tests for DataType and BaseDataType classes in codeCore.
+ * Focus on type predicates, relationships, and key operations.
+ */
+class TestDataType: FunSpec({
+
+    val dummyMemSizer = object : IMemSizer {
+        override fun memorySize(dt: DataType, numElements: Int?): Int {
+            if (dt.isPointerArray) return 2 * numElements!!
+            if (dt.isArray || dt.isSplitWordArray) {
+                require(numElements != null)
+                return when (dt.sub) {
+                    BaseDataType.BOOL, BaseDataType.BYTE, BaseDataType.UBYTE -> numElements
+                    BaseDataType.UWORD, BaseDataType.WORD -> numElements * 2
+                    BaseDataType.LONG -> numElements * 4
+                    BaseDataType.FLOAT -> numElements * 5
+                    else -> throw IllegalArgumentException("invalid sub type")
+                }
+            }
+            return when {
+                dt.isByteOrBool -> 1 * (numElements ?: 1)
+                dt.isLong -> 4 * (numElements ?: 1)
+                dt.isFloat -> 5 * (numElements ?: 1)
+                else -> 2 * (numElements ?: 1)
+            }
+        }
+
+        override fun memorySize(dt: BaseDataType): Int {
+            return memorySize(DataType.forDt(dt), null)
+        }
+    }
+
+    // ============================================================================
+    // BaseDataType Extension Property Tests
+    // ============================================================================
+
+    test("isByte extension") {
+        BaseDataType.UBYTE.isByte.shouldBeTrue()
+        BaseDataType.BYTE.isByte.shouldBeTrue()
+        BaseDataType.UWORD.isByte.shouldBeFalse()
+        BaseDataType.WORD.isByte.shouldBeFalse()
+    }
+
+    test("isByteOrBool extension") {
+        BaseDataType.UBYTE.isByteOrBool.shouldBeTrue()
+        BaseDataType.BYTE.isByteOrBool.shouldBeTrue()
+        BaseDataType.BOOL.isByteOrBool.shouldBeTrue()
+        BaseDataType.UWORD.isByteOrBool.shouldBeFalse()
+    }
+
+    test("isWord extension") {
+        BaseDataType.UWORD.isWord.shouldBeTrue()
+        BaseDataType.WORD.isWord.shouldBeTrue()
+        BaseDataType.UBYTE.isWord.shouldBeFalse()
+    }
+
+    test("isInteger extension") {
+        BaseDataType.UBYTE.isInteger.shouldBeTrue()
+        BaseDataType.WORD.isInteger.shouldBeTrue()
+        BaseDataType.LONG.isInteger.shouldBeTrue()
+        BaseDataType.FLOAT.isInteger.shouldBeFalse()
+    }
+
+    test("isNumeric extension") {
+        BaseDataType.UBYTE.isNumeric.shouldBeTrue()
+        BaseDataType.FLOAT.isNumeric.shouldBeTrue()
+        BaseDataType.BOOL.isNumeric.shouldBeFalse()
+    }
+
+    test("isSigned extension") {
+        BaseDataType.BYTE.isSigned.shouldBeTrue()
+        BaseDataType.WORD.isSigned.shouldBeTrue()
+        BaseDataType.LONG.isSigned.shouldBeTrue()
+        BaseDataType.UBYTE.isSigned.shouldBeFalse()
+    }
+
+    test("isArray extension") {
+        BaseDataType.ARRAY.isArray.shouldBeTrue()
+        BaseDataType.ARRAY_SPLITW.isArray.shouldBeTrue()
+        BaseDataType.ARRAY_POINTER.isArray.shouldBeTrue()
+        BaseDataType.UBYTE.isArray.shouldBeFalse()
+    }
+
+    test("isPointer extension") {
+        BaseDataType.POINTER.isPointer.shouldBeTrue()
+        BaseDataType.UBYTE.isPointer.shouldBeFalse()
+    }
+
+    test("isSplitWordArray extension") {
+        BaseDataType.ARRAY_SPLITW.isSplitWordArray.shouldBeTrue()
+        BaseDataType.ARRAY_POINTER.isSplitWordArray.shouldBeTrue()
+        BaseDataType.ARRAY.isSplitWordArray.shouldBeFalse()
+    }
+
+    // ============================================================================
+    // DataType Companion Object Tests
+    // ============================================================================
+
+    test("DataType.forDt creates simple types") {
+        DataType.forDt(BaseDataType.UBYTE) shouldBe DataType.UBYTE
+        DataType.forDt(BaseDataType.WORD) shouldBe DataType.WORD
+        DataType.forDt(BaseDataType.LONG) shouldBe DataType.LONG
+        DataType.forDt(BaseDataType.FLOAT) shouldBe DataType.FLOAT
+    }
+
+    test("DataType.forDt throws for struct instance") {
+        shouldThrow<NotImplementedError> {
+            DataType.forDt(BaseDataType.STRUCT_INSTANCE)
+        }
+    }
+
+    test("DataType.arrayFor creates array types") {
+        val ubyteArray = DataType.arrayFor(BaseDataType.UBYTE)
+        ubyteArray.base shouldBe BaseDataType.ARRAY
+        ubyteArray.sub shouldBe BaseDataType.UBYTE
+
+        val wordArraySplit = DataType.arrayFor(BaseDataType.WORD)
+        wordArraySplit.base shouldBe BaseDataType.ARRAY_SPLITW
+        wordArraySplit.sub shouldBe BaseDataType.WORD
+    }
+
+    test("DataType.pointer creates pointer types") {
+        val ptrByte = DataType.pointer(BaseDataType.UBYTE)
+        ptrByte.base shouldBe BaseDataType.POINTER
+        ptrByte.sub shouldBe BaseDataType.UBYTE
+    }
+
+    // ============================================================================
+    // DataType Property Tests
+    // ============================================================================
+
+    test("DataType.isBasic property") {
+        DataType.UBYTE.isBasic.shouldBeTrue()
+        DataType.WORD.isBasic.shouldBeTrue()
+        DataType.STR.isBasic.shouldBeFalse()
+        DataType.arrayFor(BaseDataType.UBYTE).isBasic.shouldBeFalse()
+    }
+
+    test("DataType.isByte property") {
+        DataType.UBYTE.isByte.shouldBeTrue()
+        DataType.BYTE.isByte.shouldBeTrue()
+        DataType.WORD.isByte.shouldBeFalse()
+    }
+
+    test("DataType.isNumeric property") {
+        DataType.UBYTE.isNumeric.shouldBeTrue()
+        DataType.FLOAT.isNumeric.shouldBeTrue()
+        DataType.BOOL.isNumeric.shouldBeFalse()
+        DataType.STR.isNumeric.shouldBeFalse()
+    }
+
+    test("DataType.isArray property") {
+        DataType.arrayFor(BaseDataType.UBYTE).isArray.shouldBeTrue()
+        DataType.UBYTE.isArray.shouldBeFalse()
+    }
+
+    test("DataType.isPointer property") {
+        DataType.pointer(BaseDataType.UBYTE).isPointer.shouldBeTrue()
+        DataType.UBYTE.isPointer.shouldBeFalse()
+    }
+
+    test("DataType.isString property") {
+        DataType.STR.isString.shouldBeTrue()
+        DataType.UBYTE.isString.shouldBeFalse()
+    }
+
+    test("DataType.isPassByRef property") {
+        DataType.STR.isPassByRef.shouldBeTrue()
+        DataType.arrayFor(BaseDataType.UBYTE).isPassByRef.shouldBeTrue()
+        DataType.UBYTE.isPassByRef.shouldBeFalse()
+        DataType.pointer(BaseDataType.UBYTE).isPassByRef.shouldBeFalse()
+    }
+
+    // ============================================================================
+    // DataType Method Tests
+    // ============================================================================
+
+    test("DataType.elementType returns element type for arrays") {
+        DataType.arrayFor(BaseDataType.UBYTE).elementType() shouldBe DataType.UBYTE
+        DataType.arrayFor(BaseDataType.WORD).elementType() shouldBe DataType.WORD
+        DataType.STR.elementType() shouldBe DataType.UBYTE
+    }
+
+    test("DataType.elementType throws for non-arrays") {
+        shouldThrow<IllegalArgumentException> {
+            DataType.UBYTE.elementType()
+        }
+    }
+
+    test("DataType.dereference for pointers") {
+        DataType.pointer(BaseDataType.UBYTE).dereference() shouldBe DataType.UBYTE
+        DataType.pointer(BaseDataType.WORD).dereference() shouldBe DataType.WORD
+        DataType.UWORD.dereference() shouldBe DataType.UBYTE
+    }
+
+    test("DataType.size with memsizer") {
+        DataType.UBYTE.size(dummyMemSizer) shouldBe 1
+        DataType.WORD.size(dummyMemSizer) shouldBe 2
+        DataType.LONG.size(dummyMemSizer) shouldBe 4
+        DataType.FLOAT.size(dummyMemSizer) shouldBe 5
+    }
+
+    // ============================================================================
+    // DataType Comparison Tests
+    // ============================================================================
+
+    test("DataType equals for same types") {
+        DataType.UBYTE shouldBe DataType.UBYTE
+        DataType.WORD shouldBe DataType.WORD
+        DataType.STR shouldBe DataType.STR
+    }
+
+    test("DataType equals for different types") {
+        DataType.UBYTE shouldNotBe DataType.BYTE
+        DataType.UBYTE shouldNotBe DataType.WORD
+    }
+
+    test("BaseDataType.largerSizeThan") {
+        BaseDataType.WORD.largerSizeThan(BaseDataType.UBYTE).shouldBeTrue()
+        BaseDataType.LONG.largerSizeThan(BaseDataType.WORD).shouldBeTrue()
+        BaseDataType.UBYTE.largerSizeThan(BaseDataType.WORD).shouldBeFalse()
+        BaseDataType.STR.largerSizeThan(BaseDataType.UBYTE).shouldBeTrue()
+        BaseDataType.STR.largerSizeThan(BaseDataType.BOOL).shouldBeTrue()
+        BaseDataType.STR.largerSizeThan(BaseDataType.UWORD).shouldBeFalse()
+        BaseDataType.STR.largerSizeThan(BaseDataType.WORD).shouldBeFalse()
+        BaseDataType.STR.largerSizeThan(BaseDataType.POINTER).shouldBeFalse()
+        BaseDataType.STR.largerSizeThan(BaseDataType.LONG).shouldBeFalse()
+        BaseDataType.POINTER.largerSizeThan(BaseDataType.UBYTE).shouldBeTrue()
+        BaseDataType.POINTER.largerSizeThan(BaseDataType.BOOL).shouldBeTrue()
+        BaseDataType.POINTER.largerSizeThan(BaseDataType.UWORD).shouldBeFalse()
+        BaseDataType.POINTER.largerSizeThan(BaseDataType.STR).shouldBeFalse()
+    }
+
+    test("BaseDataType.equalsSize") {
+        BaseDataType.UBYTE.equalsSize(BaseDataType.UBYTE).shouldBeTrue()
+        BaseDataType.UBYTE.equalsSize(BaseDataType.BYTE).shouldBeTrue()
+        BaseDataType.WORD.equalsSize(BaseDataType.UWORD).shouldBeTrue()
+        BaseDataType.UBYTE.equalsSize(BaseDataType.WORD).shouldBeFalse()
+        BaseDataType.STR.equalsSize(BaseDataType.STR).shouldBeTrue()
+        BaseDataType.STR.equalsSize(BaseDataType.UWORD).shouldBeTrue()
+        BaseDataType.STR.equalsSize(BaseDataType.BYTE).shouldBeFalse()
+        BaseDataType.POINTER.equalsSize(BaseDataType.UWORD).shouldBeTrue()
+        BaseDataType.POINTER.equalsSize(BaseDataType.STR).shouldBeFalse()
+    }
+
+    // ============================================================================
+    // DataType.isAssignableTo Tests
+    // ============================================================================
+
+    test("bool assignability") {
+        DataType.BOOL.isAssignableTo(DataType.BOOL).shouldBeTrue()
+        DataType.BOOL.isAssignableTo(DataType.UBYTE).shouldBeFalse()
+    }
+
+    test("ubyte assignability") {
+        DataType.UBYTE.isAssignableTo(DataType.UBYTE).shouldBeTrue()
+        DataType.UBYTE.isAssignableTo(DataType.UWORD).shouldBeTrue()
+        DataType.UBYTE.isAssignableTo(DataType.LONG).shouldBeTrue()
+        DataType.UBYTE.isAssignableTo(DataType.FLOAT).shouldBeTrue()
+    }
+
+    test("byte assignability") {
+        DataType.BYTE.isAssignableTo(DataType.BYTE).shouldBeTrue()
+        DataType.BYTE.isAssignableTo(DataType.WORD).shouldBeTrue()
+        DataType.BYTE.isAssignableTo(DataType.LONG).shouldBeTrue()
+    }
+
+    test("uword assignability") {
+        DataType.UWORD.isAssignableTo(DataType.UWORD).shouldBeTrue()
+        DataType.UWORD.isAssignableTo(DataType.LONG).shouldBeTrue()
+        DataType.UWORD.isAssignableTo(DataType.FLOAT).shouldBeTrue()
+    }
+
+    test("string assignability") {
+        DataType.STR.isAssignableTo(DataType.STR).shouldBeTrue()
+        DataType.STR.isAssignableTo(DataType.UWORD).shouldBeTrue()
+    }
+
+    test("pointer assignability") {
+        val ptr = DataType.pointer(BaseDataType.UBYTE)
+        ptr.isAssignableTo(DataType.UWORD).shouldBeTrue()
+        ptr.isAssignableTo(DataType.LONG).shouldBeTrue()
+        ptr.isAssignableTo(DataType.pointer(BaseDataType.UBYTE)).shouldBeTrue()
+    }
+
+    // ============================================================================
+    // DataType.toString Tests
+    // ============================================================================
+
+    test("DataType.toString for basic types") {
+        DataType.UBYTE.toString() shouldBe "ubyte"
+        DataType.WORD.toString() shouldBe "word"
+        DataType.LONG.toString() shouldBe "long"
+        DataType.FLOAT.toString() shouldBe "float"
+    }
+
+    test("DataType.toString for arrays") {
+        DataType.arrayFor(BaseDataType.UBYTE).toString() shouldBe "ubyte[]"
+        DataType.arrayFor(BaseDataType.WORD).toString() shouldBe "word[] (split)"
+    }
+})
@@ -0,0 +1,729 @@
+package prog8tests.codecore
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.booleans.shouldBeTrue
+import io.kotest.matchers.collections.shouldBeEmpty
+import io.kotest.matchers.ints.shouldBeGreaterThan
+import io.kotest.matchers.maps.shouldContainKey
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+import prog8.code.core.*
+import prog8.code.target.C128Target
+import prog8.code.target.C64Target
+import prog8.code.target.Cx16Target
+import prog8.code.target.PETTarget
+import prog8.code.target.zp.C128Zeropage
+import prog8.code.target.zp.C64Zeropage
+import prog8.code.target.zp.CX16Zeropage
+import prog8.code.target.zp.PETZeropage
+
+
+/**
+ * Comprehensive tests for Zeropage free list configurations across all targets.
+ * 
+ * Tests verify that for each target and ZeropageType combination:
+ * - The exact list of free locations is correct
+ * - Scratch locations are properly reserved
+ * - Virtual registers are allocated when appropriate
+ */
+class TestZeropageFreeList: FunSpec({
+
+    // ============================================================================
+    // Helper Functions
+    // ============================================================================
+
+    fun createOptions(target: ICompilationTarget, zpType: ZeropageType, floats: Boolean = false): CompilationOptions {
+        return CompilationOptions.builder(target)
+            .output(OutputType.RAW)
+            .zeropage(zpType)
+            .floats(floats)
+            .compilerVersion("test")
+            .build()
+    }
+
+    fun verifyScratchLocationsReserved(zp: Zeropage) {
+        // Verify scratch locations are not in free list
+        zp.free.contains(zp.SCRATCH_B1) shouldBe false
+        zp.free.contains(zp.SCRATCH_REG) shouldBe false
+        zp.free.contains(zp.SCRATCH_W1) shouldBe false
+        zp.free.contains(zp.SCRATCH_W1 + 1u) shouldBe false
+        zp.free.contains(zp.SCRATCH_W2) shouldBe false
+        zp.free.contains(zp.SCRATCH_W2 + 1u) shouldBe false
+        zp.free.contains(zp.SCRATCH_PTR) shouldBe false
+        zp.free.contains(zp.SCRATCH_PTR + 1u) shouldBe false
+    }
+
+    fun verifyVirtualRegistersAllocated(zp: Zeropage, expected: Boolean) {
+        if (expected) {
+            // Check that virtual registers are allocated
+            for (reg in 0..15) {
+                zp.allocatedVariables shouldContainKey "cx16.r${reg}"
+            }
+        }
+    }
+
+    // ============================================================================
+    // C64 Zeropage Tests
+    // ============================================================================
+
+    context("C64Zeropage") {
+        
+        test("DONTUSE should have no free locations") {
+            val options = createOptions(C64Target(), ZeropageType.DONTUSE)
+            val zp = C64Zeropage(options)
+            
+            zp.free.shouldBeEmpty()
+            zp.availableBytes() shouldBe 0
+        }
+
+        test("BASICSAFE should have specific free locations") {
+            val options = createOptions(C64Target(), ZeropageType.BASICSAFE)
+            val zp = C64Zeropage(options)
+            
+            // BASICSAFE includes specific BASIC-safe locations
+            zp.free.isNotEmpty().shouldBeTrue()
+            zp.free.size shouldBeGreaterThan 0
+            
+            // Verify scratch locations are reserved
+            verifyScratchLocationsReserved(zp)
+            
+            // Virtual registers should be allocated for BASICSAFE
+            verifyVirtualRegistersAllocated(zp, expected = false)  // C64 doesn't allocate virtual regs for BASICSAFE
+        }
+
+        test("KERNALSAFE should have larger free list than BASICSAFE") {
+            val options = createOptions(C64Target(), ZeropageType.KERNALSAFE)
+            val zp = C64Zeropage(options)
+            
+            zp.free.isNotEmpty().shouldBeTrue()
+            
+            // KERNALSAFE has more locations than BASICSAFE
+            val basicsafeOptions = createOptions(C64Target(), ZeropageType.BASICSAFE)
+            val basicsafeZp = C64Zeropage(basicsafeOptions)
+            
+            zp.free.size shouldBeGreaterThan basicsafeZp.free.size
+            
+            verifyScratchLocationsReserved(zp)
+            verifyVirtualRegistersAllocated(zp, expected = true)  // KERNALSAFE gets virtual registers
+        }
+
+        test("FLOATSAFE should exclude float-used locations") {
+            val options = createOptions(C64Target(), ZeropageType.FLOATSAFE, floats = true)
+            val zp = C64Zeropage(options)
+            
+            zp.free.isNotEmpty().shouldBeTrue()
+            
+            // FLOATSAFE should have fewer locations than KERNALSAFE due to float exclusions
+            val kernalsafeOptions = createOptions(C64Target(), ZeropageType.KERNALSAFE)
+            val kernalsafeZp = C64Zeropage(kernalsafeOptions)
+            
+            zp.free.size shouldBeLessThan kernalsafeZp.free.size
+            
+            // Some float-related locations should not be free (exact set depends on implementation)
+            // Just verify the size difference is significant
+            (kernalsafeZp.free.size - zp.free.size) shouldBeGreaterThan 10
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FULL should have maximum free locations minus IRQ") {
+            val options = createOptions(C64Target(), ZeropageType.FULL)
+            val zp = C64Zeropage(options)
+            
+            // FULL should have the most free locations
+            val kernalsafeOptions = createOptions(C64Target(), ZeropageType.KERNALSAFE)
+            val kernalsafeZp = C64Zeropage(kernalsafeOptions)
+            
+            zp.free.size shouldBeGreaterThan kernalsafeZp.free.size
+            
+            // IRQ locations should not be free
+            zp.free.contains(0xa0u) shouldBe false
+            zp.free.contains(0xa1u) shouldBe false
+            zp.free.contains(0xa2u) shouldBe false
+            zp.free.contains(0x91u) shouldBe false
+            zp.free.contains(0xc0u) shouldBe false
+            zp.free.contains(0xc5u) shouldBe false
+            zp.free.contains(0xcbu) shouldBe false
+            zp.free.contains(0xf5u) shouldBe false
+            zp.free.contains(0xf6u) shouldBe false
+            
+            verifyScratchLocationsReserved(zp)
+            verifyVirtualRegistersAllocated(zp, expected = true)
+        }
+    }
+
+    // ============================================================================
+    // CX16 Zeropage Tests
+    // ============================================================================
+
+    context("CX16Zeropage") {
+        
+        test("DONTUSE should have no free locations") {
+            val options = createOptions(Cx16Target(), ZeropageType.DONTUSE)
+            val zp = CX16Zeropage(options)
+            
+            zp.free.shouldBeEmpty()
+            zp.availableBytes() shouldBe 0
+        }
+
+        test("BASICSAFE should have 0x22-0x7F") {
+            val options = createOptions(Cx16Target(), ZeropageType.BASICSAFE)
+            val zp = CX16Zeropage(options)
+            
+            // Virtual registers 0x02-0x21 should be allocated, not free
+            for (addr in 0x02u..0x21u) {
+                zp.free shouldNotBe addr
+            }
+            
+            // Free should be 0x22-0x7F minus scratch locations
+            for (addr in 0x22u..0x7Fu) {
+                if (addr !in setOf(zp.SCRATCH_B1, zp.SCRATCH_REG, zp.SCRATCH_W1, zp.SCRATCH_W1 + 1u, 
+                        zp.SCRATCH_W2, zp.SCRATCH_W2 + 1u, zp.SCRATCH_PTR, zp.SCRATCH_PTR + 1u)) {
+                    zp.free.contains(addr) shouldBe true
+                }
+            }
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("KERNALSAFE should have 0x22-0x7F and 0xA9-0xFF") {
+            val options = createOptions(Cx16Target(), ZeropageType.KERNALSAFE)
+            val zp = CX16Zeropage(options)
+            
+            val basicsafeOptions = createOptions(Cx16Target(), ZeropageType.BASICSAFE)
+            val basicsafeZp = CX16Zeropage(basicsafeOptions)
+            
+            zp.free.size shouldBeGreaterThan basicsafeZp.free.size
+            
+            // Should include high memory range
+            zp.free.contains(0xa9u) shouldBe true
+            zp.free.contains(0xffu) shouldBe true
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FLOATSAFE should have 0x22-0x7F and 0xD4-0xFF") {
+            val options = createOptions(Cx16Target(), ZeropageType.FLOATSAFE, floats = true)
+            val zp = CX16Zeropage(options)
+
+            // Should include 0xD4-0xFF range
+            zp.free.contains(0xd4u) shouldBe true
+            zp.free.contains(0xffu) shouldBe true
+
+            // FLOATSAFE has different high range than KERNALSAFE (0xD4-0xFF vs 0xA9-0xFF)
+            val kernalsafeOptions = createOptions(Cx16Target(), ZeropageType.KERNALSAFE)
+            val kernalsafeZp = CX16Zeropage(kernalsafeOptions)
+
+            // FLOATSAFE should have fewer locations than KERNALSAFE (smaller high range)
+            zp.free.size shouldBeLessThan kernalsafeZp.free.size
+
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FULL should have 0x22-0xFF") {
+            val options = createOptions(Cx16Target(), ZeropageType.FULL)
+            val zp = CX16Zeropage(options)
+            
+            // FULL should have the most free locations
+            val kernalsafeOptions = createOptions(Cx16Target(), ZeropageType.KERNALSAFE)
+            val kernalsafeZp = CX16Zeropage(kernalsafeOptions)
+            
+            zp.free.size shouldBeGreaterThan kernalsafeZp.free.size
+            
+            // Should include all locations from 0x22 to 0xFF (minus scratch)
+            for (addr in 0x80u..0xA8u) {
+                if (addr !in setOf(zp.SCRATCH_B1, zp.SCRATCH_REG, zp.SCRATCH_W1, zp.SCRATCH_W1 + 1u,
+                        zp.SCRATCH_W2, zp.SCRATCH_W2 + 1u, zp.SCRATCH_PTR, zp.SCRATCH_PTR + 1u)) {
+                    zp.free.contains(addr) shouldBe true
+                }
+            }
+            
+            verifyScratchLocationsReserved(zp)
+        }
+    }
+
+    // ============================================================================
+    // PET Zeropage Tests
+    // ============================================================================
+
+    context("PETZeropage") {
+        
+        test("DONTUSE should have no free locations") {
+            val options = createOptions(PETTarget(), ZeropageType.DONTUSE)
+            val zp = PETZeropage(options)
+            
+            zp.free.shouldBeEmpty()
+            zp.availableBytes() shouldBe 0
+        }
+
+        test("BASICSAFE should have minimal free locations") {
+            val options = createOptions(PETTarget(), ZeropageType.BASICSAFE)
+            val zp = PETZeropage(options)
+            
+            // BASICSAFE includes scratch register addresses ($b1-$b4, $b6-$b9)
+            // and $fb-$fe. After scratch removal, $fb-$fe remain usable.
+            zp.free.size shouldBeLessThan 20
+            zp.free.contains(0xfbu) shouldBe true
+            zp.free.contains(0xfcu) shouldBe true
+            zp.free.contains(0xfdu) shouldBe true
+            zp.free.contains(0xfeu) shouldBe true
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FLOATSAFE should be same as BASICSAFE") {
+            val floatOptions = createOptions(PETTarget(), ZeropageType.FLOATSAFE, floats = true)
+            val floatZp = PETZeropage(floatOptions)
+            
+            val basicOptions = createOptions(PETTarget(), ZeropageType.BASICSAFE)
+            val basicZp = PETZeropage(basicOptions)
+            
+            // FLOATSAFE and BASICSAFE should have same free locations for PET
+            floatZp.free.size shouldBe basicZp.free.size
+            setOf(0xfbu, 0xfcu, 0xfdu, 0xfeu).forEach { addr ->
+                floatZp.free.contains(addr) shouldBe true
+            }
+        }
+
+        test("KERNALSAFE should exclude IRQ locations") {
+            val options = createOptions(PETTarget(), ZeropageType.KERNALSAFE)
+            val zp = PETZeropage(options)
+            
+            // IRQ locations should not be free
+            zp.free.contains(0x8du) shouldBe false
+            zp.free.contains(0x8eu) shouldBe false
+            zp.free.contains(0x8fu) shouldBe false
+            zp.free.contains(0x97u) shouldBe false
+            zp.free.contains(0x98u) shouldBe false
+            zp.free.contains(0x99u) shouldBe false
+            zp.free.contains(0x9au) shouldBe false
+            zp.free.contains(0x9bu) shouldBe false
+            zp.free.contains(0x9eu) shouldBe false
+            zp.free.contains(0xa7u) shouldBe false
+            zp.free.contains(0xa8u) shouldBe false
+            zp.free.contains(0xa9u) shouldBe false
+            zp.free.contains(0xaau) shouldBe false
+            zp.free.contains(0xaaau) shouldBe false
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FULL should have all locations minus IRQ") {
+            val options = createOptions(PETTarget(), ZeropageType.FULL)
+            val zp = PETZeropage(options)
+            
+            // FULL should have most locations
+            zp.free.size shouldBeGreaterThan 100
+            
+            // IRQ locations should not be free
+            zp.free.contains(0x8du) shouldBe false
+            zp.free.contains(0x97u) shouldBe false
+            zp.free.contains(0xa7u) shouldBe false
+            
+            verifyScratchLocationsReserved(zp)
+            verifyVirtualRegistersAllocated(zp, expected = true)
+        }
+    }
+
+    // ============================================================================
+    // C128 Zeropage Tests
+    // ============================================================================
+
+    context("C128Zeropage") {
+        
+        test("DONTUSE should have no free locations") {
+            val options = createOptions(C128Target(), ZeropageType.DONTUSE)
+            val zp = C128Zeropage(options)
+            
+            zp.free.shouldBeEmpty()
+            zp.availableBytes() shouldBe 0
+        }
+
+        test("BASICSAFE should have specific safe locations") {
+            val options = createOptions(C128Target(), ZeropageType.BASICSAFE)
+            val zp = C128Zeropage(options)
+            
+            zp.free.isNotEmpty().shouldBeTrue()
+            
+            // Should include some specific BASIC-safe locations (excluding scratch)
+            // 0x0b is SCRATCH_PTR, 0x74 is SCRATCH_B1 for C128, so they're not free
+            // Check for other locations that should be free
+            zp.free.contains(0x0du) shouldBe true
+            zp.free.contains(0x1bu) shouldBe true  // In BASICSAFE range
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FLOATSAFE should be same as BASICSAFE for C128") {
+            val floatOptions = createOptions(C128Target(), ZeropageType.FLOATSAFE, floats = true)
+            val floatZp = C128Zeropage(floatOptions)
+            
+            val basicOptions = createOptions(C128Target(), ZeropageType.BASICSAFE)
+            val basicZp = C128Zeropage(basicOptions)
+            
+            // FLOATSAFE and BASICSAFE should have same free locations for C128
+            floatZp.free.size shouldBe basicZp.free.size
+        }
+
+        test("KERNALSAFE should have BASIC variables area") {
+            val options = createOptions(C128Target(), ZeropageType.KERNALSAFE)
+            val zp = C128Zeropage(options)
+
+            // Should include 0x0A-0x8F (BASIC variables area) minus scratch/virtual reg locations
+            // 0x0a is where virtual registers start for C128, so not free
+            // 0x8fu should be free
+            zp.free.contains(0x8fu) shouldBe true
+
+            // Should include additional specific locations
+            zp.free.contains(0x92u) shouldBe true
+            // 0xb6u is SCRATCH_W1 for C128 - won't be free
+            zp.free.contains(0x96u) shouldBe true  // Alternative location
+            
+            verifyScratchLocationsReserved(zp)
+        }
+
+        test("FULL should have maximum locations minus IRQ") {
+            val options = createOptions(C128Target(), ZeropageType.FULL)
+            val zp = C128Zeropage(options)
+
+            // FULL should have many locations (0x0A-0xFF minus IRQ and scratch)
+            // 0x0a is where virtual registers start for C128, so not free
+            zp.free.size shouldBeGreaterThan 150
+
+            // IRQ locations should not be free
+            zp.free.contains(0x90u) shouldBe false
+            zp.free.contains(0x91u) shouldBe false
+            zp.free.contains(0xa0u) shouldBe false
+            zp.free.contains(0xa1u) shouldBe false
+            zp.free.contains(0xa2u) shouldBe false
+            zp.free.contains(0xc0u) shouldBe false
+            zp.free.contains(0xccu) shouldBe false
+            zp.free.contains(0xcdu) shouldBe false
+            zp.free.contains(0xd0u) shouldBe false
+            zp.free.contains(0xd1u) shouldBe false
+            zp.free.contains(0xd2u) shouldBe false
+            zp.free.contains(0xd3u) shouldBe false
+            zp.free.contains(0xd4u) shouldBe false
+            zp.free.contains(0xd5u) shouldBe false
+            zp.free.contains(0xf7u) shouldBe false
+            
+            verifyScratchLocationsReserved(zp)
+            verifyVirtualRegistersAllocated(zp, expected = true)
+        }
+    }
+
+    // ============================================================================
+    // Cross-Target Comparison Tests
+    // ============================================================================
+
+    context("Cross-Target Comparisons") {
+        
+        test("all targets should have empty free list for DONTUSE") {
+            // C64
+            val c64Options = createOptions(C64Target(), ZeropageType.DONTUSE)
+            C64Zeropage(c64Options).free.shouldBeEmpty()
+            
+            // CX16
+            val cx16Options = createOptions(Cx16Target(), ZeropageType.DONTUSE)
+            CX16Zeropage(cx16Options).free.shouldBeEmpty()
+            
+            // PET
+            val petOptions = createOptions(PETTarget(), ZeropageType.DONTUSE)
+            PETZeropage(petOptions).free.shouldBeEmpty()
+            
+            // C128
+            val c128Options = createOptions(C128Target(), ZeropageType.DONTUSE)
+            C128Zeropage(c128Options).free.shouldBeEmpty()
+        }
+
+        test("scratch locations differ between targets") {
+            val c64Options = createOptions(C64Target(), ZeropageType.BASICSAFE)
+            val c64Zp = C64Zeropage(c64Options)
+
+            val cx16Options = createOptions(Cx16Target(), ZeropageType.BASICSAFE)
+            val cx16Zp = CX16Zeropage(cx16Options)
+
+            val petOptions = createOptions(PETTarget(), ZeropageType.BASICSAFE)
+            val petZp = PETZeropage(petOptions)
+
+            val c128Options = createOptions(C128Target(), ZeropageType.BASICSAFE)
+            val c128Zp = C128Zeropage(c128Options)
+
+            // Each target has different scratch locations
+            c64Zp.SCRATCH_B1 shouldBe 0x02u
+            cx16Zp.SCRATCH_B1 shouldBe 0x7au
+            petZp.SCRATCH_B1 shouldBe 0xb3u
+            c128Zp.SCRATCH_B1 shouldBe 0x74u
+        }
+    }
+
+    // ============================================================================
+    // Exhaustive Zeropage Address Tests - All 256 locations
+    // ============================================================================
+
+    context("Exhaustive C64 Zeropage Tests") {
+
+        test("DONTUSE - no addresses should be free") {
+            val options = createOptions(C64Target(), ZeropageType.DONTUSE)
+            val zp = C64Zeropage(options)
+            
+            for (addr in 0x00u..0xFFu) {
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("BASICSAFE - exact free address set") {
+            val options = createOptions(C64Target(), ZeropageType.BASICSAFE)
+            val zp = C64Zeropage(options)
+            
+            // BASICSAFE: specific BASIC-safe locations plus virtual registers at 0x04-0x23
+            // Scratch locations are removed from free list
+            // Just verify key properties
+            zp.free.size shouldBeGreaterThan 10
+            
+            // Scratch locations should NOT be free
+            setOf(0x02u, 0x03u, 0x04u, 0x05u, 0xFBu, 0xFCu, 0xFDu, 0xFEu).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // Some known free locations
+            zp.free.contains(0x06u) shouldBe true
+            zp.free.contains(0x92u) shouldBe true
+        }
+
+        test("KERNALSAFE - exact free address set") {
+            val options = createOptions(C64Target(), ZeropageType.KERNALSAFE)
+            val zp = C64Zeropage(options)
+            
+            // KERNALSAFE: larger set including more locations, plus virtual registers at 0x04-0x23
+            // Scratch locations (0x02,0x03,0x04,0x05,0xFB,0xFC,0xFD,0xFE) are removed
+            // Virtual registers 0x04-0x23 are allocated (not free)
+            
+            // Just verify key properties since exact set is complex
+            zp.free.size shouldBeGreaterThan 50
+            
+            // IRQ locations should NOT be free
+            setOf(0xA0u, 0xA1u, 0xA2u, 0x91u, 0xC0u, 0xC5u, 0xCBu, 0xF5u, 0xF6u).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // Scratch locations should NOT be free
+            setOf(0x02u, 0x03u, 0x04u, 0x05u, 0xFBu, 0xFCu, 0xFDu, 0xFEu).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("FLOATSAFE - excludes float-used locations") {
+            val options = createOptions(C64Target(), ZeropageType.FLOATSAFE, floats = true)
+            val zp = C64Zeropage(options)
+            
+            // FLOATSAFE is KERNALSAFE minus float-used locations
+            zp.free.size shouldBeGreaterThan 20
+            
+            // FLOATSAFE should have fewer locations than KERNALSAFE
+            val kernalsafeOptions = createOptions(C64Target(), ZeropageType.KERNALSAFE)
+            val kernalsafeZp = C64Zeropage(kernalsafeOptions)
+            
+            zp.free.size shouldBeLessThan kernalsafeZp.free.size
+        }
+
+        test("FULL - maximum free locations minus IRQ") {
+            val options = createOptions(C64Target(), ZeropageType.FULL)
+            val zp = C64Zeropage(options)
+            
+            // FULL should have the most locations
+            zp.free.size shouldBeGreaterThan 100
+            
+            // IRQ locations should NOT be free
+            setOf(0xA0u, 0xA1u, 0xA2u, 0x91u, 0xC0u, 0xC5u, 0xCBu, 0xF5u, 0xF6u).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // Scratch locations should NOT be free
+            setOf(0x02u, 0x03u, 0x04u, 0x05u, 0xFBu, 0xFCu, 0xFDu, 0xFEu).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+    }
+
+    context("Exhaustive CX16 Zeropage Tests") {
+
+        test("DONTUSE - no addresses should be free") {
+            val options = createOptions(Cx16Target(), ZeropageType.DONTUSE)
+            val zp = CX16Zeropage(options)
+            
+            for (addr in 0x00u..0xFFu) {
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("BASICSAFE - 0x22-0x7F minus scratch and virtual registers") {
+            val options = createOptions(Cx16Target(), ZeropageType.BASICSAFE)
+            val zp = CX16Zeropage(options)
+            
+            // Virtual registers 0x02-0x21 are allocated (not free)
+            for (addr in 0x02u..0x21u) {
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // BASICSAFE: 0x22-0x7F minus scratch
+            for (addr in 0x22u..0x7Fu) {
+                val isScratch = addr in setOf(0x7Au, 0x7Bu, 0x7Cu, 0x7Du, 0x7Eu, 0x7Fu, 0x22u, 0x23u)
+                zp.free.contains(addr) shouldBe !isScratch
+            }
+            
+            // Above 0x7F should not be free for BASICSAFE
+            for (addr in 0x80u..0xFFu) {
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("KERNALSAFE - 0x22-0x7F and 0xA9-0xFF") {
+            val options = createOptions(Cx16Target(), ZeropageType.KERNALSAFE)
+            val zp = CX16Zeropage(options)
+            
+            // Virtual registers 0x02-0x21 are allocated (not free)
+            for (addr in 0x02u..0x21u) {
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // Should include 0xA9-0xFF range
+            zp.free.contains(0xA9u) shouldBe true
+            zp.free.contains(0xFFu) shouldBe true
+        }
+
+        test("FLOATSAFE - 0x22-0x7F and 0xD4-0xFF") {
+            val options = createOptions(Cx16Target(), ZeropageType.FLOATSAFE, floats = true)
+            val zp = CX16Zeropage(options)
+            
+            // Should include 0xD4-0xFF range
+            zp.free.contains(0xD4u) shouldBe true
+            zp.free.contains(0xFFu) shouldBe true
+            
+            // Should NOT include 0xA9-0xD3 range that KERNALSAFE has
+            val kernalsafeOptions = createOptions(Cx16Target(), ZeropageType.KERNALSAFE)
+            val kernalsafeZp = CX16Zeropage(kernalsafeOptions)
+            
+            zp.free.size shouldBeLessThan kernalsafeZp.free.size
+        }
+
+        test("FULL - 0x22-0xFF minus scratch") {
+            val options = createOptions(Cx16Target(), ZeropageType.FULL)
+            val zp = CX16Zeropage(options)
+            
+            // Virtual registers 0x02-0x21 are allocated (not free)
+            for (addr in 0x02u..0x21u) {
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // FULL should have most locations from 0x22-0xFF
+            zp.free.size shouldBeGreaterThan 150
+        }
+    }
+
+    context("Exhaustive PET Zeropage Tests") {
+
+        test("DONTUSE - no addresses should be free") {
+            val options = createOptions(PETTarget(), ZeropageType.DONTUSE)
+            val zp = PETZeropage(options)
+            
+            for (addr in 0x00u..0xFFu) {
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("BASICSAFE - extra fb-fe free after scratch removal") {
+            val options = createOptions(PETTarget(), ZeropageType.BASICSAFE)
+            val zp = PETZeropage(options)
+            
+            // BASICSAFE includes scratch register addresses ($b1-$b4, $b6-$b9)
+            // and $fb-$fe. After removing scratch registers from the pool,
+            // only $fb-$fe remain free.
+            zp.free.size shouldBeLessThan 15
+            setOf(0xfbu, 0xfcu, 0xfdu, 0xfeu).forEach { addr ->
+                zp.free.contains(addr) shouldBe true
+            }
+        }
+
+        test("KERNALSAFE - excludes IRQ locations") {
+            val options = createOptions(PETTarget(), ZeropageType.KERNALSAFE)
+            val zp = PETZeropage(options)
+            
+            // IRQ locations should NOT be free
+            setOf(0x8Du, 0x8Eu, 0x8Fu, 0x97u, 0x98u, 0x99u, 0x9Au, 0x9Bu, 0x9Eu,
+                  0xA7u, 0xA8u, 0xA9u, 0xAAu).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("FULL - all minus IRQ locations") {
+            val options = createOptions(PETTarget(), ZeropageType.FULL)
+            val zp = PETZeropage(options)
+            
+            // FULL should have most locations
+            zp.free.size shouldBeGreaterThan 150
+            
+            // IRQ locations should NOT be free
+            setOf(0x8Du, 0x97u, 0xA7u).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+    }
+
+    context("Exhaustive C128 Zeropage Tests") {
+
+        test("DONTUSE - no addresses should be free") {
+            val options = createOptions(C128Target(), ZeropageType.DONTUSE)
+            val zp = C128Zeropage(options)
+            
+            for (addr in 0x00u..0xFFu) {
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+
+        test("BASICSAFE - specific safe locations") {
+            val options = createOptions(C128Target(), ZeropageType.BASICSAFE)
+            val zp = C128Zeropage(options)
+            
+            // BASICSAFE has specific locations
+            zp.free.size shouldBeGreaterThan 50
+            
+            // Note: Virtual registers are NOT allocated for BASICSAFE on C128
+            // (only for FULL and KERNALSAFE modes)
+        }
+
+        test("KERNALSAFE - BASIC variables area 0x0A-0x8F") {
+            val options = createOptions(C128Target(), ZeropageType.KERNALSAFE)
+            val zp = C128Zeropage(options)
+            
+            // Virtual registers at 0x0A-0x29 are allocated (not free)
+            for (addr in 0x0Au..0x29u) {
+                zp.free.contains(addr) shouldBe false
+            }
+            
+            // Should include some locations in BASIC variables area
+            zp.free.contains(0x8Fu) shouldBe true
+        }
+
+        test("FULL - 0x0A-0xFF minus IRQ") {
+            val options = createOptions(C128Target(), ZeropageType.FULL)
+            val zp = C128Zeropage(options)
+            
+            // FULL should have many locations
+            zp.free.size shouldBeGreaterThan 150
+            
+            // IRQ locations should NOT be free
+            setOf(0x90u, 0x91u, 0xA0u, 0xA1u, 0xA2u, 0xC0u, 0xCCu, 0xCDu,
+                  0xD0u, 0xD1u, 0xD2u, 0xD3u, 0xD4u, 0xD5u, 0xF7u).forEach { addr ->
+                zp.free.contains(addr) shouldBe false
+            }
+        }
+    }
+})
+
+// Helper infix function for readability
+infix fun Int.shouldBeLessThan(value: Int) {
+    if (this >= value) {
+        throw AssertionError("Expected $this to be less than $value")
+    }
+}
@@ -5,39 +5,8 @@ plugins {
 dependencies {
    implementation(project(":codeCore"))
    implementation(project(":simpleAst"))
-    // implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
-    // implementation "org.jetbrains.kotlin:kotlin-reflect"
-    implementation("com.michael-bull.kotlin-result:kotlin-result-jvm:2.1.0")
+    implementation("com.michael-bull.kotlin-result:kotlin-result-jvm:2.3.1")

-    testImplementation("io.kotest:kotest-runner-junit5-jvm:5.9.1")
-    testImplementation("io.kotest:kotest-framework-datatest:5.9.1")
-}
-
-sourceSets {
-    main {
-        java {
-            setSrcDirs(listOf("$projectDir/src"))
-        }
-        resources {
-            setSrcDirs(listOf("$projectDir/res"))
-        }
-    }
-    test {
-        java {
-            setSrcDirs(listOf("$projectDir/test"))
-        }
-    }
-}
-
-tasks.test {
-    // Enable JUnit 5 (Gradle 4.6+).
-    useJUnitPlatform()
-
-    // Always run tests, even when nothing changed.
-    dependsOn("cleanTest")
-
-    // Show test results.
-    testLogging {
-        events("skipped", "failed")
-    }
+    testImplementation(testFixtures(project(":codeCore")))
+    testImplementation("io.kotest:kotest-runner-junit5")
 }
@@ -1,19 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" inherit-compiler-output="true">
-    <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
-      <excludeFolder url="file://$MODULE_DIR$/build" />
-    </content>
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
-    <orderEntry type="module" module-name="codeCore" />
-    <orderEntry type="module" module-name="simpleAst" />
-    <orderEntry type="library" name="michael.bull.kotlin.result.jvm" level="project" />
-    <orderEntry type="library" name="io.kotest.runner.junit5.jvm" level="project" />
-    <orderEntry type="library" name="io.kotest.framework.datatest" level="project" />
-  </component>
-</module>
@@ -1,30 +1,43 @@
 package prog8.codegen.cpu6502

 import prog8.code.ast.PtAsmSub
+import prog8.code.ast.PtSubroutineParameter
+import prog8.code.core.CombinedLongRegisters
 import prog8.code.core.Cx16VirtualRegisters
 import prog8.code.core.RegisterOrPair
+import prog8.code.core.RegisterOrStatusflag


-fun asmsub6502ArgsEvalOrder(sub: PtAsmSub): List<Int> {
+fun asmsub6502ArgsEvalOrder(sub: PtAsmSub, argComplexity: List<Boolean>): List<Int> {
    val order = mutableListOf<Int>()
    // order is:
-    //  1) cx16 virtual word registers,
-    //  2) paired CPU registers,
-    //  3) single CPU registers (order Y,X,A),
-    //  4) floating point registers (FAC1, FAC2),
-    //  5) CPU Carry status flag
+    //  1) combined cx16 virtual registers (longs),
+    //  2) cx16 virtual word registers,
+    //  3) paired CPU registers,
+    //  4) single CPU registers (order Y,X,A),
+    //  5) floating point registers (FAC1, FAC2),
+    //  6) CPU Carry status flag
+    // Within each group, complex expressions are evaluated first (they may clobber registers,
+    // so running them before simple expressions avoids needing to save/restore already-loaded values).
    val args = sub.parameters.withIndex()
-    val (cx16regs, args2) = args.partition { it.value.first.registerOrPair in Cx16VirtualRegisters }
+    val (combinedLongRegs, args1) = args.partition { it.value.first.registerOrPair in CombinedLongRegisters }
+    val (cx16regs, args2) = args1.partition { it.value.first.registerOrPair in Cx16VirtualRegisters }
    val pairedRegisters = arrayOf(RegisterOrPair.AX, RegisterOrPair.AY, RegisterOrPair.XY)
    val (pairedRegs , args3) = args2.partition { it.value.first.registerOrPair in pairedRegisters }
    val (singleRegsMixed, rest) = args3.partition { it.value.first.registerOrPair != null }
    val (singleCpuRegs, floatRegs) = singleRegsMixed.partition {it.value.first.registerOrPair != RegisterOrPair.FAC1 && it.value.first.registerOrPair != RegisterOrPair.FAC2  }

-    cx16regs.forEach { order += it.index }
-    pairedRegs.forEach { order += it.index }
-    singleCpuRegs.sortedBy { it.value.first.registerOrPair!!.asCpuRegister() }.asReversed().forEach { order += it.index }
+    combinedLongRegs.sortedByDescending { argComplexity[it.index] }.forEach { order += it.index }
+    cx16regs.sortedByDescending { argComplexity[it.index] }.forEach { order += it.index }
+    pairedRegs.sortedByDescending { argComplexity[it.index] }.forEach { order += it.index }
+    singleCpuRegs
+        .sortedWith(
+            compareByDescending<IndexedValue<Pair<RegisterOrStatusflag, PtSubroutineParameter>>> { argComplexity[it.index] }
+                .thenByDescending { it.value.first.registerOrPair!!.asCpuRegister() }
+        )
+        .forEach { order += it.index }
    require(rest.all { it.value.first.registerOrPair==null && it.value.first.statusflag!=null})
-    floatRegs.forEach { order += it.index }
+    floatRegs.sortedByDescending { argComplexity[it.index] }.forEach { order += it.index }
    rest.forEach { order += it.index }
    require(order.size==sub.parameters.size)

@@ -17,6 +17,10 @@ internal class AssemblyProgram(
        outputDir: Path,
        private val compTarget: ICompilationTarget) : IAssemblyProgram {

+    override val irInstructionCount: Int = 0
+    override val irChunkCount: Int = 0
+    override val irRegisterCount: Int = 0
+
    private val assemblyFile = outputDir.resolve("$name.asm")
    private val prgFile = outputDir.resolve("$name.prg")        // CBM prg executable program
    private val xexFile = outputDir.resolve("$name.xex")        // Atari xex executable program
@@ -132,9 +136,27 @@ internal class AssemblyProgram(
        }

        val proc = ProcessBuilder(assemblerCommand)
-        if(!options.quiet)
-            proc.inheritIO()
-        val process = proc.start()
+            .redirectErrorStream(true)
+
+        if (options.quiet) {
+            proc.redirectOutput(ProcessBuilder.Redirect.DISCARD)
+        }
+
+        val process = try {
+            proc.start()
+        } catch (e: Exception) {
+            System.err.println("daemon: assembler failed to start: ${e.message}")
+            return false
+        }
+
+        if (!options.quiet) {
+            process.inputStream.bufferedReader().use { reader ->
+                reader.forEachLine {
+                    println(it)
+                }
+            }
+        }
+
        val result = process.waitFor()
        if (result == 0) {
            removeGeneratedLabelsFromMonlist()
@@ -42,12 +42,129 @@ internal class ForLoopsAsmGen(
        when {
            iterableDt.isByteArray -> forOverNonconstByteRange(stmt, iterableDt, range)
            iterableDt.isWordArray && !iterableDt.isSplitWordArray -> forOverNonconstWordRange(stmt, iterableDt, range)
-            else -> throw AssemblyError("range expression can only be byte or word")
+            iterableDt.isLongArray -> forOverNonconstLongRange(stmt, iterableDt, range)
+            else -> throw AssemblyError("range expression can only be byte, word or long")
        }

        asmgen.loopEndLabels.removeLast()
    }

+    private fun forOverNonconstLongRange(stmt: PtForLoop, iterableDt: DataType, range: PtRange) {
+        val stepsize = range.step.asConstInteger()!!
+        val loopLabel = asmgen.makeLabel("for_loop")
+        val endLabel = asmgen.makeLabel("for_end")
+        asmgen.loopEndLabels.add(endLabel)
+        val varname = asmgen.asmVariableName(stmt.variable)
+        
+        asmgen.assignExpressionToVariable(range.from, varname, iterableDt.elementType())
+
+        if (stepsize == 1 || stepsize == -1)
+            forOverLongsRangeStepOne(range, varname, iterableDt, loopLabel, endLabel, stmt)
+        else
+            forOverLongsRangeStepGreaterOne(range, varname, iterableDt, loopLabel, endLabel, stmt)
+    }
+
+    private fun forOverLongsRangeStepOne(range: PtRange, varname: String, iterableDt: DataType, loopLabel: String, endLabel: String, forloop: PtForLoop) {
+        val stepsize = range.step.asConstInteger()!!
+        
+        // Use temporary variable to store the limit
+        val toValueVar = asmgen.createTempVarReused(iterableDt.elementType().base, false, range)
+        asmgen.assignExpressionToVariable(range.to, toValueVar, iterableDt.elementType())
+
+        if (stepsize == 1) {
+            // Increment toValueVar to make the loop inclusive (0 to N runs N+1 times)
+            asmgen.out("""
+                inc  $toValueVar
+                bne  +
+                inc  $toValueVar+1
+                bne  +
+                inc  $toValueVar+2
+                bne  +
+                inc  $toValueVar+3
+    +
+            """)
+        } else {
+            // Decrement toValueVar to make the loop inclusive (N downto 0 runs N+1 times)
+            val label1 = asmgen.makeLabel("dec_1")
+            val label2 = asmgen.makeLabel("dec_2")
+            val label3 = asmgen.makeLabel("dec_3")
+            asmgen.out("""
+                lda  $toValueVar
+                bne  $label1
+                lda  $toValueVar+1
+                bne  $label2
+                lda  $toValueVar+2
+                bne  $label3
+                dec  $toValueVar+3
+    $label3:    dec  $toValueVar+2
+    $label2:    dec  $toValueVar+1
+    $label1:    dec  $toValueVar
+            """)
+        }
+
+        asmgen.out(loopLabel)
+        asmgen.translate(forloop.statements)
+
+        if (stepsize == 1) {
+            asmgen.out("""
+                inc  $varname
+                bne  +
+                inc  $varname+1
+                bne  +
+                inc  $varname+2
+                bne  +
+                inc  $varname+3
+               lda  $varname
+                cmp  $toValueVar
+                bne  $loopLabel
+                lda  $varname+1
+                cmp  $toValueVar+1
+                bne  $loopLabel
+                lda  $varname+2
+                cmp  $toValueVar+2
+                bne  $loopLabel
+                lda  $varname+3
+                cmp  $toValueVar+3
+                bne  $loopLabel
+            """)
+        } else {
+            asmgen.out("""
+                lda  $varname
+                bne  +++
+                lda  $varname+1
+                bne  ++
+                lda  $varname+2
+                bne  +
+                dec  $varname+3
+               dec  $varname+2
+               dec  $varname+1
+               dec  $varname
+                lda  $varname
+                cmp  $toValueVar
+                bne  $loopLabel
+                lda  $varname+1
+                cmp  $toValueVar+1
+                bne  $loopLabel
+                lda  $varname+2
+                cmp  $toValueVar+2
+                bne  $loopLabel
+                lda  $varname+3
+                cmp  $toValueVar+3
+                bne  $loopLabel
+            """)
+        }
+        asmgen.out(endLabel)
+    }
+
+    private fun forOverLongsRangeStepGreaterOne(range: PtRange, varname: String, iterableDt: DataType, loopLabel: String, endLabel: String, forloop: PtForLoop) {
+        // TODO: implement 32-bit loop
+        asmgen.romableError("for loops over long ranges with step != 1 not yet fully implemented", forloop.position)
+        asmgen.out(loopLabel)
+        asmgen.translate(forloop.statements)
+        asmgen.jmp(loopLabel)
+        asmgen.out(endLabel)
+    }
+
    private fun forOverNonconstByteRange(stmt: PtForLoop, iterableDt: DataType, range: PtRange) {
        val stepsize = range.step.asConstInteger()!!
        val loopLabel = asmgen.makeLabel("for_loop")
@@ -727,23 +844,28 @@ $loopLabel          sty  $indexVar
            if(range.step==1 && range.last>range.first) return translateForSimpleWordRangeAsc(stmt, range)
            if(range.step==-1 && range.last<range.first) return translateForSimpleWordRangeDesc(stmt, range)
        }
+        else if(iterableDt.isLongArray) {
+            if(range.last==range.first) return translateForSimpleLongRangeAsc(stmt, range)
+            if(range.step==1 && range.last>range.first) return translateForSimpleLongRangeAsc(stmt, range)
+            if(range.step==-1 && range.last<range.first) return translateForSimpleLongRangeDesc(stmt, range)
+        }

        // not one of the easy cases, generate more complex code...
        val loopLabel = asmgen.makeLabel("for_loop")
        val endLabel = asmgen.makeLabel("for_end")
        asmgen.loopEndLabels.add(endLabel)
+        val varname = asmgen.asmVariableName(stmt.variable)
        when {
            iterableDt.isByteArray -> {
                // loop over byte range via loopvar, step >= 2 or <= -2
-                val varname = asmgen.asmVariableName(stmt.variable)
                asmgen.out("""
                            lda  #${range.first}
                            sta  $varname
 $loopLabel""")
                asmgen.translate(stmt.statements)
                when (range.step) {
-                    0, 1, -1 -> {
-                        throw AssemblyError("step 0, 1 and -1 should have been handled specifically  $range ${stmt.position}")
+                    1, -1 -> {
+                        throw AssemblyError("step 1 and -1 should have been handled specifically  $range ${stmt.position}")
                    }
                    2 -> {
                        if(range.last==255 || range.last==254) {
@@ -800,10 +922,9 @@ $loopLabel""")
            }
            iterableDt.isWordArray && !iterableDt.isSplitWordArray -> {
                // loop over word range via loopvar, step >= 2 or <= -2
-                val varname = asmgen.asmVariableName(stmt.variable)
                when (range.step) {
-                    0, 1, -1 -> {
-                        throw AssemblyError("step 0, 1 and -1 should have been handled specifically  $stmt")
+                    1, -1 -> {
+                        throw AssemblyError("step 1 and -1 should have been handled specifically  $stmt")
                    }
                    else -> {
                        // word, step >= 2 or <= -2
@@ -821,7 +942,6 @@ $loopLabel""")
                            bne  +
                            lda  $varname+1
                            cmp  #>${range.last}
-                            bne  +
                            beq  $endLabel
 +                           lda  $varname
                            clc
@@ -835,7 +955,61 @@ $loopLabel""")
                    }
                }
            }
-            else -> throw AssemblyError("range expression can only be byte or word")
+            iterableDt.isLongArray -> {
+                // loop over long range via loopvar, step >= 2 or <= -2
+                when(range.step) {
+                    1, -1 -> {
+                        throw AssemblyError("step 1 and -1 should have been handled specifically  $stmt")
+                    }
+                    else -> {
+                        // long, step >= 2 or <= -2
+                        // note: range.last has already been adjusted by kotlin itself to actually be the last value of the sequence
+                        val from = range.first.toLongHex()
+                        val to = range.last.toLongHex()
+                        val step = range.step.toLongHex()
+                        asmgen.out("""
+                            lda  #$${from.substring(6, 8)}
+                            sta  $varname
+                            lda  #$${from.substring(4, 6)}
+                            sta  $varname+1
+                            lda  #$${from.substring(2, 4)}
+                            sta  $varname+2
+                            lda  #$${from.take(2)}
+                            sta  $varname+3
+$loopLabel""")
+                        asmgen.translate(stmt.statements)
+                        asmgen.out("""
+                            lda  $varname
+                            cmp  #$${to.substring(6, 8)}
+                            bne  +
+                            lda  $varname+1
+                            cmp  #$${to.substring(4, 6)}
+                            bne  +
+                            lda  $varname+2
+                            cmp  #$${to.substring(2, 4)}
+                            bne  +
+                            lda  $varname+3
+                            cmp  #$${to.take(2)}
+                            beq  $endLabel
+                           lda  $varname
+                            clc
+                            adc  #$${step.substring(6, 8)}
+                            sta  $varname
+                            lda  $varname+1
+                            adc  #$${step.substring(4, 6)}
+                            sta  $varname+1
+                            lda  $varname+2
+                            adc  #$${step.substring(2, 4)}
+                            sta  $varname+2
+                            lda  $varname+3
+                            adc  #$${step.take(2)}
+                            sta  $varname+3""")
+                        asmgen.jmp(loopLabel)
+                        asmgen.out(endLabel)
+                    }
+                }
+            }
+            else -> throw AssemblyError("invalid range expression datatype")
        }
        asmgen.loopEndLabels.removeLast()
    }
@@ -904,6 +1078,7 @@ $loopLabel""")
    }

    private fun translateForSimpleWordRangeAsc(stmt: PtForLoop, range: IntProgression) {
+        require(range.step==1)
        val loopLabel = asmgen.makeLabel("for_loop")
        val endLabel = asmgen.makeLabel("for_end")
        asmgen.loopEndLabels.add(endLabel)
@@ -931,6 +1106,7 @@ $loopLabel""")
    }

    private fun translateForSimpleWordRangeDesc(stmt: PtForLoop, range: IntProgression) {
+        require(range.step==-1)
        val loopLabel = asmgen.makeLabel("for_loop")
        val endLabel = asmgen.makeLabel("for_end")
        asmgen.loopEndLabels.add(endLabel)
@@ -967,6 +1143,110 @@ $loopLabel""")
        asmgen.loopEndLabels.removeLast()
    }

+    private fun translateForSimpleLongRangeAsc(stmt: PtForLoop, range: IntProgression) {
+        require(range.step==1)
+        val loopLabel = asmgen.makeLabel("for_loop")
+        val endLabel = asmgen.makeLabel("for_end")
+        asmgen.loopEndLabels.add(endLabel)
+        val varname = asmgen.asmVariableName(stmt.variable)
+        val from = range.first.toLongHex()
+        val to = range.last.toLongHex()
+        asmgen.out("""
+            lda  #$${from.substring(6, 8)}
+            sta  $varname
+            lda  #$${from.substring(4, 6)}
+            sta  $varname+1
+            lda  #$${from.substring(2, 4)}
+            sta  $varname+2
+            lda  #$${from.take(2)}
+            sta  $varname+3
+$loopLabel""")
+        asmgen.translate(stmt.statements)
+        asmgen.out("""
+            lda  $varname
+            cmp  #$${to.substring(6, 8)}
+            bne  +
+            lda  $varname+1
+            cmp  #$${to.substring(4, 6)}
+            bne  +
+            lda  $varname+2
+            cmp  #$${to.substring(2, 4)}
+            bne  +
+            lda  $varname+3
+            cmp  #$${to.take(2)}
+            beq  $endLabel
+           inc  $varname
+            bne  $loopLabel
+            inc  $varname+1
+            bne  $loopLabel
+            inc  $varname+2
+            bne  $loopLabel
+            inc  $varname+3""")
+        asmgen.jmp(loopLabel)
+        asmgen.out(endLabel)
+        asmgen.loopEndLabels.removeLast()
+    }
+
+    private fun translateForSimpleLongRangeDesc(stmt: PtForLoop, range: IntProgression) {
+        require(range.step==-1)
+        val loopLabel = asmgen.makeLabel("for_loop")
+        val endLabel = asmgen.makeLabel("for_end")
+        asmgen.loopEndLabels.add(endLabel)
+        val varname = asmgen.asmVariableName(stmt.variable)
+        val from = range.first.toLongHex()
+        val to = range.last.toLongHex()
+        asmgen.out("""
+            lda  #$${from.substring(6, 8)}
+            sta  $varname
+            lda  #$${from.substring(4, 6)}
+            sta  $varname+1
+            lda  #$${from.substring(2, 4)}
+            sta  $varname+2
+            lda  #$${from.take(2)}
+            sta  $varname+3
+$loopLabel""")
+        asmgen.translate(stmt.statements)
+        if(range.last==0) {
+            asmgen.out("""
+                lda  $varname
+                bne  ++++
+                lda  $varname+1
+                bne  +++
+                lda  $varname+2
+                bne  ++
+                lda  $varname+3
+                beq  $endLabel""")
+        } else {
+            asmgen.out("""
+                lda  $varname
+                cmp  #$${to.substring(6, 8)}
+                bne  +
+                lda  $varname+1
+                cmp  #$${to.substring(4, 6)}
+                bne  +
+                lda  $varname+2
+                cmp  #$${to.substring(2, 4)}
+                bne  +
+                lda  $varname+3
+                cmp  #$${to.take(2)}
+                beq  $endLabel""")
+        }
+        asmgen.out("""
+           lda  $varname
+            bne  +++
+            lda  $varname+1
+            bne  ++
+            lda  $varname+2
+            bne  +
+            dec  $varname+3
+           dec  $varname+2
+           dec  $varname+1
+           dec  $varname""")
+        asmgen.jmp(loopLabel)
+        asmgen.out(endLabel)
+        asmgen.loopEndLabels.removeLast()
+    }
+
    private fun assignLoopvarWord(stmt: PtForLoop, range: PtRange) =
        asmgen.assignExpressionToVariable(
            range.from,
@@ -9,6 +9,16 @@ import prog8.codegen.cpu6502.assignment.AsmAssignment
 import prog8.codegen.cpu6502.assignment.TargetStorageKind


+/*
+ * CRITICAL: `inline asmsub` subroutines MUST be inlined at the call site.
+ * They are NOT called with jsr - their assembly body is copied directly into the caller.
+ * This means: no .proc/.pend, no rts, no jsr. The return value is left in the appropriate
+ * CPU register (A/X/Y) and the caller picks it up.
+ *
+ * This is handled at line 68: `if (sub.inline) { ... }`.
+ * Any new codegen backend MUST replicate this behavior.
+ */
+
 internal class FunctionCallAsmGen(private val program: PtProgram, private val asmgen: AsmGen6502Internal) {

    internal fun translateFunctionCallStatement(stmt: PtFunctionCall) {
@@ -33,7 +43,7 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
        // NOTE: does NOT output code to save/restore the X register for this call! Every caller should deal with this in their own way!!
        //       (you can use subroutine.shouldSaveX() and saveX()/restoreX() routines as a help for this)

-        val symbol = asmgen.symbolTable.lookup(call.name)!!
+        val symbol = asmgen.symbolTable.lookup(call.name) ?: asmgen.symbolTable.lookupUnscoped(call.name) ?: throw IllegalStateException("Symbol not found: ${call.name}")
        if(symbol.type == StNodeType.LABEL) {
            require(call.void)
            asmgen.out("  jsr  ${asmgen.asmSymbolName(symbol.scopedNameString)}")
@@ -44,6 +54,26 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
        val subAsmName = asmgen.asmSymbolName(call.name)

        if(sub is PtAsmSub) {
+            val varBank = sub.address?.varbank
+            var varbank: String? = null
+            var bankFixLabel: String? = null
+            if (varBank != null) {
+                // the bank variable can also be the name of a subroutine that should be called to return the bank byte dynamically
+                val bankSymbol = asmgen.symbolTable.lookup(varBank.name) ?: asmgen.symbolTable.lookupUnscoped(varBank.name)
+                if (bankSymbol?.type == StNodeType.SUBROUTINE || bankSymbol?.type == StNodeType.EXTSUB) {
+                    val extsubId = asmgen.extsubCallSiteIds[sub]
+                    if (extsubId != null) {
+                        asmgen.out("  lda  #${extsubId.toInt()}")
+                    }
+                    asmgen.out("  jsr  ${asmgen.asmSymbolName(varBank.name)}")
+                    // store bank byte directly into the JSRFAR instruction data (forward label reference)
+                    bankFixLabel = asmgen.makeLabel("bank")
+                    asmgen.out("  sta  $bankFixLabel")
+                } else {
+                    varbank = asmgen.asmVariableName(varBank)
+                }
+            }
+
            argumentsViaRegisters(sub, call)
            if (sub.inline) {
                // inline the subroutine. (regardless of optimization settings!)
@@ -56,54 +86,57 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
            } else {
                val bank = sub.address?.constbank?.toString()
                if(bank==null) {
-                    val varbank = if(sub.address?.varbank==null) null else asmgen.asmVariableName(sub.address!!.varbank!!)
-                    if(varbank!=null) {
+                    if(varbank!=null || bankFixLabel!=null) {
                        if(asmgen.options.romable)
                            TODO("no codegen yet for non-const bank in subroutine call that's usable in ROM  ${call.position}")

+                        // variable bank case: save/restore registers around the self-modifying sta
+                        if(varbank!=null) {
+                            asmgen.out("""
+                                php
+                                pha
+                                lda  $varbank
+                                sta  +
+                                pla
+                                plp""")
+                        }
+                        val label = bankFixLabel ?: "+"
+
                        // self-modifying code: set jsrfar bank argument
                        when(asmgen.options.compTarget.name) {
                            "cx16" -> {
                                // JSRFAR can jump to a banked RAM address as well!
                                asmgen.out("""
-                                php
-                                pha
-                                lda  $varbank
-                                sta  +
-                                pla
-                                plp
                                jsr  cx16.JSRFAR
                                .word  $subAsmName    ; ${sub.address!!.address.toHex()}
-+                               .byte  0    ; modified"""
+$label .byte  0    ; modified"""
                                )
                            }
                            "c64" -> {
                                asmgen.out("""
-                                php
-                                pha
-                                lda  $varbank
-                                sta  +
-                                pla
-                                plp
                                jsr  c64.x16jsrfar
                                .word  $subAsmName    ; ${sub.address!!.address.toHex()}
-+                               .byte  0    ; modified"""
+$label .byte  0    ; modified"""
                                )
                            }
                            "c128" -> {
                                asmgen.out("""
-                                php
-                                pha
-                                lda  $varbank
-                                sta  +
-                                pla
-                                plp
                                jsr  c128.x16jsrfar
                                .word  $subAsmName    ; ${sub.address!!.address.toHex()}
-+                               .byte  0    ; modified"""
+$label .byte  0    ; modified"""
                                )
                            }
-                            else -> throw AssemblyError("callfar is not supported on the selected compilation target")
+                            else -> {
+                                if(asmgen.options.compTarget.supportsBankedCalls) {
+                                    val targetName = asmgen.options.compTarget.name
+                                    asmgen.out("""
+                                        jsr  $targetName.x16jsrfar
+                                        .word  $subAsmName    ; ${sub.address!!.address.toHex()}
+$label .byte  0    ; modified"""
+                                    )
+                                } else
+                                    throw AssemblyError("callfar is not supported on the selected compilation target")
+                            }
                        }
                    } else {
                        asmgen.out("  jsr  $subAsmName")
@@ -133,7 +166,17 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
                                .byte  $bank"""
                            )
                        }
-                        else -> throw AssemblyError("callfar is not supported on the selected compilation target")
+                        else -> {
+                            if(asmgen.options.compTarget.supportsBankedCalls) {
+                                val targetName = asmgen.options.compTarget.name
+                                asmgen.out("""
+                                    jsr  $targetName.x16jsrfar
+                                    .word  $subAsmName    ; ${sub.address!!.address.toHex()}
+                                    .byte  $bank"""
+                                )                                
+                            } else
+                                throw AssemblyError("callfar is not supported on the selected compilation target")
+                        }
                    }
                }
            }
@@ -203,15 +246,16 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as

    private fun usesOtherRegistersWhileEvaluating(arg: PtExpression): Boolean {
        return when(arg) {
-            is PtBuiltinFunctionCall -> {
-                if (arg.name in arrayOf("lsb", "msb", "lsw", "msw"))
-                    return usesOtherRegistersWhileEvaluating(arg.args[0])
-                if (arg.name == "mkword" || arg.name == "mklong2")
-                    return usesOtherRegistersWhileEvaluating(arg.args[0]) || usesOtherRegistersWhileEvaluating(arg.args[1])
-                if (arg.name == "mklong")
-                    return usesOtherRegistersWhileEvaluating(arg.args[0]) || usesOtherRegistersWhileEvaluating(arg.args[1]) ||
-                           usesOtherRegistersWhileEvaluating(arg.args[2]) || usesOtherRegistersWhileEvaluating(arg.args[3])
-                return !arg.isSimple()
+            is PtFunctionCall if arg.builtin -> {
+                if (arg.name in setOf("lsb", "msb", "lsw", "msw"))
+                    usesOtherRegistersWhileEvaluating(arg.args[0])
+                else if (arg.name == "mkword" || arg.name == "mklong2")
+                    usesOtherRegistersWhileEvaluating(arg.args[0]) || usesOtherRegistersWhileEvaluating(arg.args[1])
+                else if (arg.name == "mklong")
+                    usesOtherRegistersWhileEvaluating(arg.args[0]) || usesOtherRegistersWhileEvaluating(arg.args[1]) ||
+                    usesOtherRegistersWhileEvaluating(arg.args[2]) || usesOtherRegistersWhileEvaluating(arg.args[3])
+                else
+                    !arg.isSimple()
            }
            is PtAddressOf -> false
            is PtIdentifier -> false
@@ -233,7 +277,8 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
        if(sub.parameters.size==1) {
            argumentViaRegister(sub, IndexedValue(0, sub.parameters.single().second), call.args[0])
        } else {
-            val optimalEvalOrder = asmsub6502ArgsEvalOrder(sub)
+            val argComplexity = call.args.map { usesOtherRegistersWhileEvaluating(it) }
+            val optimalEvalOrder = asmsub6502ArgsEvalOrder(sub, argComplexity)
            optimalEvalOrder.forEach {
                val param = sub.parameters[it]
                val arg = call.args[it]
@@ -267,8 +312,8 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as

        val reg = parameter.register
        if(reg!=null) {
-            require(reg in Cx16VirtualRegisters) { "can only use R0-R15 'registers' here" }
-            val varName = "cx16.${reg.name.lowercase()}"
+            require(reg in Cx16VirtualRegisters || reg in CombinedLongRegisters) { "can only use R0-R15 'registers' here" }
+            val varName = reg.asScopedNameVirtualReg(value.type).joinToString(".")
            asmgen.assignExpressionToVariable(value, varName, parameter.type)
        } else {
            val varName = asmgen.asmVariableName(sub.scopedName + "." + parameter.name)
@@ -279,7 +324,7 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
    private fun argumentViaRegister(sub: IPtSubroutine, parameter: IndexedValue<PtSubroutineParameter>, value: PtExpression, registerOverride: RegisterOrPair? = null): RegisterOrStatusflag {
        // pass argument via a register parameter
        if(!isArgumentTypeCompatible(value.type, parameter.value.type))
-            throw AssemblyError("argument type incompatible")
+            throw AssemblyError("argument type incompatible ${value.type} vs param ${parameter.value.type} at ${parameter.value.position}")

        val paramRegister: RegisterOrStatusflag = when(sub) {
            is PtAsmSub -> if(registerOverride==null) sub.parameters[parameter.index].first else RegisterOrStatusflag(registerOverride, null)
@@ -290,11 +335,11 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
        val requiredDt = parameter.value.type
        if(requiredDt!=value.type) {
            if(value.type.largerSizeThan(requiredDt))
-                throw AssemblyError("can only convert byte values to word param types")
+                throw AssemblyError("can only convert byte values to word param types ${value.position}")
        }
        if (statusflag!=null) {
            if(requiredDt!=value.type)
-                throw AssemblyError("for statusflag, byte or bool value is required")
+                throw AssemblyError("for statusflag, byte or bool value is required ${value.position}")
            if (statusflag == Statusflag.Pc) {
                // this boolean param needs to be set last, right before the jsr
                // for now, this is already enforced on the subroutine definition by the Ast Checker
@@ -322,7 +367,7 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
                        asmgen.out("  ror  a")
                    }
                }
-            } else throw AssemblyError("can only use Carry as status flag parameter")
+            } else throw AssemblyError("can only use Carry as status flag parameter ${value.position}")
            return RegisterOrStatusflag(null, statusflag)
        }
        else {
@@ -332,7 +377,7 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
                // we need to sign extend the source, do this via temporary word variable
                asmgen.assignExpressionToVariable(value, "P8ZP_SCRATCH_W1", DataType.UBYTE)
                asmgen.signExtendVariableLsb("P8ZP_SCRATCH_W1", value.type.base)
-                asmgen.assignVariableToRegister("P8ZP_SCRATCH_W1", register, null, Position.DUMMY)
+                asmgen.assignVariableToRegister("P8ZP_SCRATCH_W1", register, null, value.position)
            } else {
                val scope = value.definingISub()
                val target: AsmAssignTarget =
@@ -342,8 +387,8 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
                        AsmAssignTarget.fromRegisters(register, parameter.value.type.isSigned, value.position, scope, asmgen)
                    }
                val src = if(value.type.isPassByRef) {
-                    if(value is PtIdentifier) {
-                        val addr = PtAddressOf(value.type.typeForAddressOf(false), false, Position.DUMMY)
+                    if(value is PtIdentifier || value is PtPointerDeref) {
+                        val addr = PtAddressOf(value.type.typeForAddressOf(false), false, value.position)
                        addr.add(value)
                        addr.parent = scope as PtNode
                        AsmAssignSource.fromAstSource(addr, program, asmgen).adjustSignedUnsigned(target)
@@ -362,12 +407,17 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
    private fun isArgumentTypeCompatible(argType: DataType, paramType: DataType): Boolean {
        if(argType isAssignableTo paramType)
            return true
-        if(argType.isBool && paramType.isBool)
-            return true
+
+        // signed/unsigned args vs parameters are considered compatible
        if(argType.isByte && paramType.isByte)
            return true
        if(argType.isWord && paramType.isWord)
            return true
+// only signed longs and floats are available so these were already covered
+//        if(argType.isLong && paramType.isLong)
+//            return true
+//        if(argType.isFloat && paramType.isFloat)
+//            return true

        // we have a special rule for some types.
        // strings are assignable to UWORD, for example, and vice versa
@@ -376,6 +426,9 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
        if(argType.isUnsignedWord && paramType.isString)
            return true

+        if (argType.isArray && (paramType.isString || paramType.isPointerToByte))
+            return true
+
        return false
    }
 }
@@ -352,7 +352,7 @@ internal class ProgramAndVarsGen(
        val varsInBlock = getVars(scope)

        // Zeropage Variables
-        val varnames = varsInBlock.filter { it.value.type==StNodeType.STATICVAR }.map { it.value.scopedNameString }.toSet()
+        val varnames = varsInBlock.filter { it.value.type==StNodeType.STATICVAR }.mapTo(mutableSetOf()) { it.value.scopedNameString }
        zeropagevars2asm(varnames)

        // MemDefs and Consts
@@ -372,13 +372,14 @@ internal class ProgramAndVarsGen(
    }

    private fun asmTypeString(dt: DataType): String {
+        val effectiveDt = if(dt.isArray) dt.elementType() else dt
        return when {
-            dt.isBool || dt.isUnsignedByte -> ".byte"
-            dt.isSignedByte -> ".char"
-            dt.isUnsignedWord || dt.isPointer -> ".word"
-            dt.isSignedWord -> ".sint"
-            dt.isLong -> ".dint"
-            dt.isFloat -> ".byte"
+            effectiveDt.isBool || effectiveDt.isUnsignedByte -> ".byte"
+            effectiveDt.isSignedByte -> ".char"
+            effectiveDt.isUnsignedWord || effectiveDt.isPointer -> ".word"
+            effectiveDt.isSignedWord -> ".sint"
+            effectiveDt.isLong -> ".dint"
+            effectiveDt.isFloat -> ".byte"
            else -> {
                throw AssemblyError("weird dt")
            }
@@ -387,58 +388,67 @@ internal class ProgramAndVarsGen(

    private fun structInstances2asm() {

-        fun initValues(instance: StStructInstance): List<String> {
-            val structtype: StStruct = symboltable.lookup(instance.structName) as StStruct
-            return structtype.fields.zip(instance.initialValues).map { (field, value) ->
-                if(field.first.isFloat) {
-                    "["+compTarget.getFloatAsmBytes(value.number!!)+"]"
-                } else {
-                    when {
-                        value.number!=null -> {
-                            if(field.first.isPointer)
-                                "$"+value.number!!.toInt().toString(16)
-                            else if(field.first.isInteger)
-                                value.number!!.toInt().toString()
-                            else
-                                value.number.toString()
-                        }
-                        value.addressOfSymbol!=null -> value.addressOfSymbol!!
-                        value.boolean!=null -> if(value.boolean==true) "1" else "0"
-                        else -> throw AssemblyError("weird struct initial value $value")
-                    }
+        fun formatValue(value: StArrayElement, dt: DataType): String {
+            if(dt.isFloat) {
+                val numValue = (value as? StArrayElement.Number)?.value
+                    ?: throw AssemblyError("expected number for float field")
+                return "["+compTarget.getFloatAsmBytes(numValue)+"]"
+            }
+            return when (value) {
+                is StArrayElement.Number -> {
+                    if(dt.isPointer)
+                        "$"+value.value.toInt().toString(16)
+                    else if(dt.isInteger)
+                        value.value.toInt().toString()
+                    else
+                        value.value.toString()
+                }
+                is StArrayElement.AddressOf -> value.symbol
+                is StArrayElement.MemorySlab -> "$StMemorySlabBlockName.${value.name}"
+                is StArrayElement.BoolValue -> if(value.value) "1" else "0"
+                is StArrayElement.StructInstance -> throw AssemblyError("struct instance in struct initializer")
+            }
+        }
+
+        fun flatInitValues(instance: StStructInstance, structtype: StStruct): List<String> {
+            var valueIndex = 0
+            return structtype.fields.flatMap { field ->
+                val arraySz = field.arraySize
+                val count = arraySz ?: 1
+                val elemDt = if(arraySz!=null) field.type.elementType() else field.type
+                (0 until count).map {
+                    val value = instance.initialValues[valueIndex++]
+                    formatValue(value, elemDt)
                }
            }
        }

-
        asmgen.out("; struct types")
-        symboltable.allStructInstances.distinctBy { it.structName }.forEach {
-            val structtype: StStruct = symboltable.lookup(it.structName) as StStruct
-            val structargs = structtype.fields.withIndex().joinToString(",") { field -> "f${field.index}" }
-            asmgen.out("${it.structName}    .struct $structargs\n")
-            structtype.fields.withIndex().forEach { (index, field) ->
-                val dt = field.first
-                val varname = "f${index}"
-                val type = asmTypeString(dt)
-                asmgen.out("p8v_${field.second}  $type  \\$varname")        // note: struct field symbol prefixing done here because that is a lot simpler than fixing up all expressions in the AST
+        symboltable.allStructTypes().distinctBy { it.name }.forEach { structtype ->
+            val paramFields = structtype.fields.filter { !it.isArray }
+            val structargs = paramFields.indices.joinToString(",") { "f$it" }
+            asmgen.out("${structtype.scopedNameString}    .struct $structargs\n")
+            var paramIdx = 0
+            for(field in structtype.fields) {
+                val type = asmTypeString(field.type)
+                if(field.isArray) {
+                    val anonymous = List(field.arraySize!!) { "?" }.joinToString(",")
+                    asmgen.out("p8v_${field.name}  $type  $anonymous")
+                } else {
+                    asmgen.out("p8v_${field.name}  $type  \\f$paramIdx")
+                    paramIdx++
+                }
            }
            asmgen.out("    .endstruct\n")
        }

-        val (instancesNoInit, instances) = symboltable.allStructInstances.partition { it.initialValues.isEmpty() }
+        val (instancesNoInit, instances) = symboltable.allStructInstances().partition { it.initialValues.isEmpty() }
        asmgen.out("; struct instances without initialization values, as BSS zeroed at startup\n")
        asmgen.out("    .section BSS\n")
        asmgen.out("${StStructInstanceBlockName}_bss  .block\n")
        instancesNoInit.forEach {
            val structtype: StStruct = symboltable.lookup(it.structName) as StStruct
-            val zerovalues = structtype.fields.map { field ->
-                if(field.first.isFloat) {
-                    val floatbytes = List(compTarget.memorySize(BaseDataType.FLOAT)) { "?" }
-                    "[${floatbytes.joinToString(",")}]"
-                }
-                else "?"
-            }
-            asmgen.out("${it.name}    .dstruct  ${it.structName}, ${zerovalues.joinToString(",")}\n")
+            asmgen.out("${it.name}    .fill  ${structtype.size}\n")
        }
        asmgen.out("    .endblock\n")
        asmgen.out("    .send BSS\n")
@@ -446,9 +456,28 @@ internal class ProgramAndVarsGen(
        asmgen.out("; struct instances with initialization values\n")
        asmgen.out("    .section STRUCTINSTANCES\n")
        asmgen.out("$StStructInstanceBlockName  .block\n")
-        instances.forEach {
-            val instancename = it.name.substringAfter('.')
-            asmgen.out("$instancename    .dstruct  ${it.structName}, ${initValues(it).joinToString(",")}\n")
+        instances.forEach { instance ->
+            val instancename = instance.name.substringAfter('.')
+            val structtype: StStruct = symboltable.lookup(instance.structName) as StStruct
+            val values = flatInitValues(instance, structtype)
+            val hasArrays = structtype.fields.any { fld -> fld.isArray }
+            if(hasArrays) {
+                asmgen.out(instancename)
+                var valueIndex = 0
+                for(field in structtype.fields) {
+                    val arraySz = field.arraySize
+                    val count = arraySz ?: 1
+                    val elemDt = if(arraySz!=null) field.type.elementType() else field.type
+                    val type = asmTypeString(elemDt)
+                    val fieldValues = (0 until count).joinToString(",") {
+                        formatValue(instance.initialValues[valueIndex++], elemDt)
+                    }
+                    asmgen.out("  $type  $fieldValues")
+                }
+                asmgen.out("\n")
+            } else {
+                asmgen.out("$instancename    .dstruct  ${instance.structName}, ${values.joinToString(",")}\n")
+            }
        }
        asmgen.out("    .endblock\n")
        asmgen.out("    .send STRUCTINSTANCES\n")
@@ -503,7 +532,7 @@ internal class ProgramAndVarsGen(
        val varsInSubroutine = getVars(scope)

        // Zeropage Variables
-        val varnames = varsInSubroutine.filter { it.value.type==StNodeType.STATICVAR }.map { it.value.scopedNameString }.toSet()
+        val varnames = varsInSubroutine.filter { it.value.type==StNodeType.STATICVAR }.mapTo(mutableSetOf()) { it.value.scopedNameString }
        zeropagevars2asm(varnames)

        // MemDefs and Consts
@@ -615,18 +644,26 @@ internal class ProgramAndVarsGen(
            arrayVarsWithInitInZp.forEach {
                val size = it.alloc.size
                val name = asmgen.asmVariableName(it.name)
-                asmgen.out("""
-                    lda  #<${name}_init_value
-                    ldy  #>${name}_init_value
-                    sta  cx16.r0
-                    sty  cx16.r0+1
-                    lda  #<${name}
-                    ldy  #>${name}
-                    sta  cx16.r1
-                    sty  cx16.r1+1
-                    lda  #<$size
-                    ldy  #>$size
-                    jsr  sys.memcopy""")
+                if(it.alloc.dt.isSplitWordArray) {
+                    val halfSize = size / 2
+                    if(halfSize>0) {
+                        asmgen.out("""
+                            ldx  #${halfSize-1}
+                    -       lda  ${name}_init_value_lsb,x
+                            sta  ${name}_lsb,x
+                            lda  ${name}_init_value_msb,x
+                            sta  ${name}_msb,x
+                            dex
+                            bpl  -""")
+                    }
+                } else {
+                    asmgen.out("""
+                        ldx  #${size-1}
+                -       lda  ${name}_init_value,x
+                        sta  ${name},x
+                        dex
+                        bpl  -""")
+                }
            }
            asmgen.out("  jmp  +")
        }
@@ -740,7 +777,7 @@ internal class ProgramAndVarsGen(
                    it.initializationStringValue!!.second,
                    it.initializationStringValue!!.first
                )
-                asmgen.romableError("string (${it.dt} ${it.name}) can only be used as read-only in ROMable code", Position.DUMMY, false)     // TODO print warning with position of the var
+                asmgen.romableError("string (${it.dt} ${it.name}) can only be used as read-only in ROMable code", it.astNode?.position ?: Position.DUMMY, false)
            }
            alignedStrings.sortedBy { it.align }.forEach {
                outputStringvar(
@@ -749,22 +786,22 @@ internal class ProgramAndVarsGen(
                    it.initializationStringValue!!.second,
                    it.initializationStringValue!!.first
                )
-                asmgen.romableError("string (${it.dt} ${it.name}) can only be used as read-only in ROMable code", Position.DUMMY, false)     // TODO print warning with position of the var
+                asmgen.romableError("string (${it.dt} ${it.name}) can only be used as read-only in ROMable code", it.astNode?.position ?: Position.DUMMY, false)
            }

            notAlignedOther.sortedBy { it.type }.forEach {
                staticVariable2asm(it)
                if(it.dt.isArray)
-                    asmgen.romableError("array (${it.dt} ${it.name}) can only be used as read-only in ROMable code", Position.DUMMY, false)     // TODO print warning with position of the var
+                    asmgen.romableError("array (${it.dt} ${it.name}) can only be used as read-only in ROMable code", it.astNode?.position ?: Position.DUMMY, false)
                else
-                    asmgen.romableError("inlined variable (${it.dt} ${it.name})", Position.DUMMY)       // TODO print warning with position of the var
+                    asmgen.romableError("inlined variable (${it.dt} ${it.name})", it.astNode?.position ?: Position.DUMMY)
            }
            alignedOther.sortedBy { it.align }.sortedBy { it.type }.forEach {
                staticVariable2asm(it)
                if(it.dt.isArray)
-                    asmgen.romableError("array (${it.dt} ${it.name}) can only be used as read-only in ROMable code", Position.DUMMY, false)     // TODO print warning with position of the var
+                    asmgen.romableError("array (${it.dt} ${it.name}) can only be used as read-only in ROMable code", it.astNode?.position ?: Position.DUMMY, false)
                else
-                    asmgen.romableError("inlined variable (${it.dt} ${it.name})", Position.DUMMY)       // TODO print warning with position of the var
+                    asmgen.romableError("inlined variable (${it.dt} ${it.name})", it.astNode?.position ?: Position.DUMMY)
            }
        }
    }
@@ -872,14 +909,14 @@ internal class ProgramAndVarsGen(
            dt.isSplitWordArray -> {
                if(dt.elementType().isUnsignedWord || dt.elementType().isPointer) {
                    val data = makeArrayFillDataUnsigned(dt, value, orNumberOfZeros)
-                    asmgen.out("_array_$varname := ${data.joinToString()}")
-                    asmgen.out("${varname}_lsb\t.byte <_array_$varname")
-                    asmgen.out("${varname}_msb\t.byte >_array_$varname")
+                    asmgen.out("${varname}_words := ${data.joinToString()}")
+                    asmgen.out("${varname}_lsb\t.byte <${varname}_words")
+                    asmgen.out("${varname}_msb\t.byte >${varname}_words")
                } else {
                    val data = makeArrayFillDataSigned(dt, value, orNumberOfZeros)
-                    asmgen.out("_array_$varname := ${data.joinToString()}")
-                    asmgen.out("${varname}_lsb\t.byte <_array_$varname")
-                    asmgen.out("${varname}_msb\t.byte >_array_$varname")
+                    asmgen.out("${varname}_words := ${data.joinToString()}")
+                    asmgen.out("${varname}_lsb\t.byte <${varname}_words")
+                    asmgen.out("${varname}_msb\t.byte >${varname}_words")
                }
            }
            dt.isUnsignedWordArray -> {
@@ -915,7 +952,9 @@ internal class ProgramAndVarsGen(
            dt.isFloatArray -> {
                val array = value ?: zeroFilledArray(orNumberOfZeros!!)
                val floatFills = array.map {
-                    compTarget.getFloatAsmBytes(it.number!!)
+                    val numValue = (it as? StArrayElement.Number)?.value 
+                        ?: throw AssemblyError("expected number for float array")
+                    compTarget.getFloatAsmBytes(numValue)
                }
                asmgen.out(varname)
                for (f in array.zip(floatFills))
@@ -926,11 +965,7 @@ internal class ProgramAndVarsGen(
    }

    private fun zeroFilledArray(numElts: Int): StArray {
-        val values = mutableListOf<StArrayElement>()
-        repeat(numElts) {
-            values.add(StArrayElement(0.0, null, null,null,null))
-        }
-        return values
+        return List(numElts) { StArrayElement.Number(0.0) }
    }

    private fun memdefsAndConsts2asm(memvars: Collection<StMemVar>, consts: Collection<StConstant>) {
@@ -938,10 +973,17 @@ internal class ProgramAndVarsGen(
            asmgen.out("  ${it.name} = ${it.address.toHex()}")
        }
        consts.sortedBy { it.name }.forEach {
+            val nameWithoutColons = it.name.replace("::", "_")
            if(it.dt.isFloat)
-                asmgen.out("  ${it.name} = ${it.value}")
-            else
-                asmgen.out("  ${it.name} = ${it.value.toHex()}")
+                asmgen.out("  ${nameWithoutColons} = ${it.value}")
+            else {
+                if(it.value!=null)
+                    asmgen.out("  ${nameWithoutColons} = ${it.value!!.toHex()}")
+                else if(it.memorySlab!=null)
+                    asmgen.out("  ${nameWithoutColons} = ${StMemorySlabBlockName}.${it.memorySlab!!.name}")
+                else
+                    TODO("asm gen for ${nameWithoutColons} = memory alloc?")
+            }
        }
    }

@@ -971,41 +1013,35 @@ internal class ProgramAndVarsGen(
        val array = value ?: zeroFilledArray(orNumberOfZeros!!)
        return when {
            dt.isBoolArray ->
-                // byte array can never contain pointer-to types, so treat values as all integers
                array.map {
-                    if(it.boolean!=null)
-                        if(it.boolean==true) "1" else "0"
-                    else {
-                        val number = it.number!!
-                        if(number==0.0) "0" else "1"
+                    when(it) {
+                        is StArrayElement.BoolValue -> if(it.value) "1" else "0"
+                        is StArrayElement.Number -> if(it.value==0.0) "0" else "1"
+                        else -> throw AssemblyError("unexpected array element type for bool array")
                    }
                }
            dt.isUnsignedByteArray ->
-                // byte array can never contain pointer-to types, so treat values as all integers
                array.map {
-                    val number = it.number!!.toInt()
-                    "$"+number.toString(16).padStart(2, '0')
+                    val numValue = (it as? StArrayElement.Number)?.value 
+                        ?: throw AssemblyError("expected number for ubyte array")
+                    "$"+numValue.toInt().toString(16).padStart(2, '0')
                }
            dt.isArray && (dt.elementType().isUnsignedWord || dt.elementType().isPointer) -> array.map {
-                if(it.number!=null) {
-                    "$" + it.number!!.toInt().toString(16).padStart(4, '0')
-                }
-                else if(it.addressOfSymbol!=null) {
-                    val addrOfSymbol = it.addressOfSymbol!!
-                    val symbol = symboltable.lookup(addrOfSymbol)!!
-                    if(symbol is StStaticVariable && symbol.dt.isSplitWordArray)
-                        asmgen.asmSymbolName(addrOfSymbol+"_lsb")  // the _lsb split array comes first in memory
-                    else
-                        asmgen.asmSymbolName(addrOfSymbol)
-                }
-                else if(it.structInstance!=null) {
-                    asmgen.asmSymbolName("${StStructInstanceBlockName}.${it.structInstance!!}")
-                }
-                else if(it.structInstanceUninitialized!=null) {
-                    asmgen.asmSymbolName("${StStructInstanceBlockName}_bss.${it.structInstanceUninitialized!!}")
-                }
-                else {
-                    throw AssemblyError("weird array elt")
+                when(it) {
+                    is StArrayElement.Number -> "$" + it.value.toInt().toString(16).padStart(4, '0')
+                    is StArrayElement.AddressOf -> {
+                        val symbol = symboltable.lookup(it.symbol)!!
+                        if(symbol is StStaticVariable && symbol.dt.isSplitWordArray)
+                            asmgen.asmSymbolName(it.symbol+"_lsb")
+                        else
+                            asmgen.asmSymbolName(it.symbol)
+                    }
+                    is StArrayElement.MemorySlab -> asmgen.asmSymbolName("$StMemorySlabBlockName.${it.name}")
+                    is StArrayElement.StructInstance -> {
+                        val prefix = if(it.uninitialized) "${StStructInstanceBlockName}_bss" else StStructInstanceBlockName
+                        asmgen.asmSymbolName("$prefix.${it.name}")
+                    }
+                    is StArrayElement.BoolValue -> throw AssemblyError("bool in word array")
                }
            }
            else -> throw AssemblyError("invalid dt")
@@ -1015,41 +1051,66 @@ internal class ProgramAndVarsGen(
    private fun makeArrayFillDataSigned(dt: DataType, value: StArray?, orNumberOfZeros: Int?): List<String> {
        val array = value ?: zeroFilledArray(orNumberOfZeros!!)
        return when {
-            // byte array can never contain pointer-to types, so treat values as all integers
            dt.isUnsignedByteArray ->
                array.map {
-                    val number = it.number!!.toInt()
+                    val numValue = (it as? StArrayElement.Number)?.value 
+                        ?: throw AssemblyError("expected number for ubyte array")
+                    val number = numValue.toInt()
                    "$"+number.toString(16).padStart(2, '0')
                }
            dt.isSignedByteArray ->
                array.map {
-                    val number = it.number!!.toInt()
+                    val numValue = (it as? StArrayElement.Number)?.value 
+                        ?: throw AssemblyError("expected number for byte array")
+                    val number = numValue.toInt()
                    val hexnum = number.absoluteValue.toString(16).padStart(2, '0')
-                    if(number>=0)
-                        "$$hexnum"
-                    else
-                        "-$$hexnum"
+                    if(number>=0) "$$hexnum" else "-$$hexnum"
+                }
+            dt.isArray && (dt.elementType().isUnsignedWord || dt.elementType().isPointer) ->
+                array.map {
+                    when(it) {
+                        is StArrayElement.Number -> "$" + it.value.toInt().toString(16).padStart(4, '0')
+                        is StArrayElement.AddressOf -> {
+                            val symbol = symboltable.lookup(it.symbol)!!
+                            if(symbol is StStaticVariable && symbol.dt.isSplitWordArray)
+                                asmgen.asmSymbolName(it.symbol+"_lsb")
+                            else
+                                asmgen.asmSymbolName(it.symbol)
+                        }
+                        is StArrayElement.MemorySlab -> asmgen.asmSymbolName("$StMemorySlabBlockName.${it.name}")
+                        is StArrayElement.StructInstance -> {
+                            val prefix = if(it.uninitialized) "${StStructInstanceBlockName}_bss" else StStructInstanceBlockName
+                            asmgen.asmSymbolName("$prefix.${it.name}")
+                        }
+                        is StArrayElement.BoolValue -> throw AssemblyError("bool in word array")
+                    }
+                }
+            dt.isSignedWordArray ->
+                array.map {
+                    when(it) {
+                        is StArrayElement.Number -> {
+                            val number = it.value.toInt()
+                            val hexnum = number.absoluteValue.toString(16).padStart(4, '0')
+                            if (number >= 0) "$$hexnum" else "-$$hexnum"
+                        }
+                        is StArrayElement.AddressOf -> asmgen.asmSymbolName(it.symbol)
+                        is StArrayElement.MemorySlab -> asmgen.asmSymbolName("$StMemorySlabBlockName.${it.name}")
+                        else -> throw AssemblyError("unexpected array element type for signed word array")
+                    }
+                }
+            dt.isLongArray ->
+                array.map {
+                    when(it) {
+                        is StArrayElement.Number -> {
+                            val number = it.value.toInt()
+                            val hexnum = number.absoluteValue.toLongHex()
+                            if (number >= 0) "$$hexnum" else "-$$hexnum"
+                        }
+                        is StArrayElement.AddressOf -> asmgen.asmSymbolName(it.symbol)
+                        is StArrayElement.MemorySlab -> asmgen.asmSymbolName("$StMemorySlabBlockName.${it.name}")
+                        else -> throw AssemblyError("unexpected array element type for long array")
+                    }
                }
-            dt.isArray && (dt.elementType().isUnsignedWord || dt.elementType().isPointer) -> array.map {
-                val number = it.number!!.toInt()
-                "$" + number.toString(16).padStart(4, '0')
-            }
-            dt.isSignedWordArray -> array.map {
-                val number = it.number!!.toInt()
-                val hexnum = number.absoluteValue.toString(16).padStart(4, '0')
-                if(number>=0)
-                    "$$hexnum"
-                else
-                    "-$$hexnum"
-            }
-            dt.isLongArray -> array.map {
-                val number = it.number!!.toInt()
-                val hexnum = number.absoluteValue.toLongHex()
-                if(number>=0)
-                    "$$hexnum"
-                else
-                    "-$$hexnum"
-            }
            else -> throw AssemblyError("invalid dt")
        }
    }