Commander X16 improvements

README.md

@@ -20,7 +20,7 @@ For build instructions, see [Build instructions](./COMPILING.md).
     
     * other Commodore computers: C16, Plus/4, C128, PET, VIC-20 (stock or with RAM extensions)
     
-    * other 6502-based machines: Famicom/NES, Atari 8-bit computers, BBC Micro, Apple II+/IIe/Enhanced IIe, Atari 2600 (experimental)
+    * other 6502-based machines: Famicom/NES, Atari 8-bit computers, BBC Micro, Apple II+/IIe/Enhanced IIe, Atari 2600 (experimental), Commander X16 (experimental)
     
     * Z80-based machines: ZX Spectrum 48k, NEC PC-88, Amstrad CPC, MSX
     

docs/README.md

@@ -60,6 +60,8 @@
 
 * [Game Boy–only modules](stdlib/gb.md)
 
+* [X16–only modules](stdlib/x16.md)
+
 ## Implementation details
 
 * [Variable storage](abi/variable-storage.md)

docs/doc_index.md

@@ -60,6 +60,8 @@
 
 * [Game Boy–only modules](stdlib/gb.md)
 
+* [X16–only modules](stdlib/x16.md)
+
 ## Implementation details
 
 * [Variable storage](abi/variable-storage.md)

docs/lang/preprocessor.md

@@ -112,6 +112,8 @@ See [the ROM vs RAM guide](../api/rom-vs-ram.md) for more information.
 
 * `NULLPTR` – physical value of `nullptr`, default 0
 
+* `VERA_VERSION` – on Commander X16, the version of the VERA chip: `7` for 0.7, `8` for 0.8
+
 ### Built-in preprocessor functions and operators
 
 The `defined` function returns 1 if the feature is defined, 0 otherwise.  

docs/stdlib/x16.md

@@ -0,0 +1,122 @@
+[< back to index](../doc_index.md)
+
+# Commander X16-oriented modules
+
+**WARNING!** Commander X16 is not yet a finalised design.
+Therefore, both the device itself and the modules for its support may change at any moment.
+
+## x16_kernal module
+
+The `x16_kernal` module is imported automatically on the X16 target.
+
+Currently, it automatically imports the [`c64_kernal` module](./c64.md).
+
+## `x16_hardware` module
+
+The `x16_hardware` module is imported automatically on the X16 target.
+
+#### `void set_ram_bank(byte)`
+
+Switches the RAM segment at $A000-$BFFF.
+
+#### `void set_rom_bank(byte)`
+
+Switches the ROM segment at $C000-$DFFF.
+
+#### `void vera_poke(int24 address, byte value)`
+
+Writes a byte into the VERA memory space.
+
+#### `void vera_fill(int24 address, byte value, word size)`
+
+Writes `size` bytes into the VERA memory space.
+
+#### `void vera_upload(int24 address, pointer source, byte size)`
+#### `void vera_upload_large(int24 address, pointer source, word size)`
+
+Copies `size` bytes from the RAM at address `source` into the VERA memory space at address `address`.
+
+#### `struct vera_layer_setup`
+
+Hardware register values for a video layer:
+
+    byte ctrl0
+    byte ctrl1
+    word map_base
+    word tile_base
+    word hscroll
+    word vscroll
+
+#### `void set_vera_layer1(pointer.vera_layer_setup)`
+
+Sets up the layer 1.
+
+#### `void set_vera_layer2(pointer.vera_layer_setup)`
+
+Sets up the layer 2.
+    
+#### `struct vera_sprite_data`
+
+Hardware register values for a sprite:
+
+    word address
+    word x
+    word y
+    byte ctrl0
+    byte ctrl1
+    
+#### `const int24 VERA_COMPOSER_CTRL`
+#### `const int24 VERA_PALETTE`
+#### `const int24 VERA_LAYER_1`
+#### `const int24 VERA_LAYER_2`
+#### `const int24 VERA_SPRITE_CTRL`
+#### `const int24 VERA_SPRITES`
+
+Various addresses in the VERA memory space.
+
+## `x16_joy` module
+
+The `x16_joy` module implements a joystick driver compatible with the `joy` module.
+
+#### `void read_joy1()`
+
+Reads the joystick from the port 1.
+
+#### `void read_joy2()`
+
+Reads the joystick from the port 1.
+
+#### `void read_also_joy1()`
+
+Reads the joystick from the port 1 and adds its readouts to the current readouts.
+
+#### `void read_also_joy2()`
+
+Reads the joystick from the port 2 and adds its readouts to the current readouts.
+
+#### `byte input_*`
+
+The following variables have the value 1 if the key is pressed and 0 if not:
+
+**Warning:** The assignment of NES controller buttons and keyboard keys may change in the future.   
+
+Variable       | SNES controller | NES controller | Keyboard (joy 1 only)
+---------------|-----------------|----------------|----------------------
+`input_a`      | A               |                |
+`input_b`      | B               | A              | Ctrl
+`input_x`      | X               | B              | Alt
+`input_y`      | Y               |                |
+`input_start`  | Start           | Start          | Enter
+`input_select` | Select          | Select         | Space
+`input_l`      | L               |                |
+`input_r`      | R               |                |
+ 
+ 
+`input_b` is an alias for `input_btn`. Single-button games should use `input_btn` for compatibility.
+ 
+## x16_joy1_default module
+
+Defines the joystick in port 1 as the default joystick.
+
+#### `alias read_joy = read_joy1`
+

examples/x16/balls.mfk

@@ -33,9 +33,9 @@ void main () {
         vy[i] = 1 - (rand() & 2)
     }
     vera_upload_large($10000, sprite_bitmap.addr, sizeof(sprite_bitmap))
-    vera_upload_large($40800, sprites.addr, sizeof(sprites))
+    vera_upload_large(VERA_SPRITES, sprites.addr, sizeof(sprites))
     // enable sprites:
-    vera_poke($40020, 1)
+    vera_poke(VERA_SPRITE_CTRL, 1)
     while true {
         for i,0,paralleluntil,SPRITE_COUNT {
             p = sprites[i].pointer
@@ -50,7 +50,7 @@ void main () {
             if y == 0 { vy[i] = 1 }
             if y >= 480-32 { vy[i] = 0-1 }
         }
-        vera_upload_large($40800, sprites.addr, sizeof(sprites))
+        vera_upload_large(VERA_SPRITES, sprites.addr, sizeof(sprites))
     }
 }
 

examples/x16/palette.mfk

@@ -2,12 +2,12 @@ void main() {
     word i
     byte hn, ln
     // 256-colour text mode for layer 0
-    vera_poke($40000, $21)
+    vera_poke(VERA_LAYER_1, $21)
     // 8×8 tiles, 64×64 tile map
-    vera_poke($40001, $35)
+    vera_poke(VERA_LAYER_1+1, $35)
     // 2× zoom in
-    vera_poke($40041, $40)
-    vera_poke($40042, $40)
+    vera_poke(VERA_COMPOSER_CTRL+1, $40)
+    vera_poke(VERA_COMPOSER_CTRL+2, $40)
     i = 0
     while i < $2000 {
         vera_poke(i, $A0)

include/x16_experimental.ini

@@ -7,29 +7,39 @@
 arch=cmos
 encoding=petscii
 screen_encoding=petscr
-modules=loader_0801,c64_kernal,x16_hardware,c64_panic,stdlib
+modules=loader_0801,x16_kernal,x16_hardware,c64_panic,stdlib
 
 [allocation]
-; list of free zp pointer locations is the same as C64
-zp_pointers=$FB,$FD,$43,$45,$47,$4B,$F7,$F9,$9E,$9B,$3D
-segments=default,himem0
+; Let's not use the BASIC:
+zp_pointers=0-$8F,$FB-$FF
+segments=default,himem_00,himem_ff
 default_code_segment=default
 segment_default_start=$80D
 segment_default_codeend=$9eff
 segment_default_datastart=after_code
 segment_default_end=$9eff
 
-segment_himem0_start=$c000
-segment_himem0_codeend=$dfff
-segment_himem0_datastart=after_code
-segment_himem0_end=$dfff
+segment_himem_00_start=$a000
+segment_himem_00_codeend=$bfff
+segment_himem_00_datastart=after_code
+segment_himem_00_end=$bfff
+segment_himem_00_bank=$00
+
+segment_himem_ff_start=$a000
+segment_himem_ff_codeend=$bfff
+segment_himem_ff_datastart=after_code
+segment_himem_ff_end=$bfff
+segment_himem_ff_bank=$ff
 
 [define]
 CBM=1
+COMMANDER_X16=1
 WIDESCREEN=1
 KEYBOARD=1
-JOYSTICKS=0
+JOYSTICKS=2
 HAS_BITMAP_MODE=1
+; Use VERA 0.7, as this is what the emulator implements:
+VERA_VERSION=7
 
 [output]
 style=single

include/x16_hardware.mfk

@@ -1,9 +1,35 @@
-// TODO: bankswitching
 
+#if VERA_VERSION == 7
+
+const int24 VERA_COMPOSER_CTRL = $40040
+const int24 VERA_PALETTE = $40200
+const int24 VERA_LAYER_1 = $40000
+const int24 VERA_LAYER_2 = $40010
+const int24 VERA_SPRITE_CTRL = $40020
+const int24 VERA_SPRITES = $40800
 
 volatile byte vera_addr_hi @ $9f20
 volatile byte vera_addr_mi @ $9f21
 volatile byte vera_addr_lo @ $9f22
+
+#elseif VERA_VERSION == 8
+
+const int24 VERA_COMPOSER_CTRL = $F0000
+const int24 VERA_PALETTE = $F1000
+const int24 VERA_LAYER_1 = $F2000
+const int24 VERA_LAYER_2 = $F3000
+const int24 VERA_SPRITE_CTRL = $F4000
+const int24 VERA_SPRITES = $F5000
+
+volatile byte vera_addr_hi @ $9f22
+volatile byte vera_addr_mi @ $9f21
+volatile byte vera_addr_lo @ $9f20
+volatile int24 vera_addr @ $9f20
+
+#else
+#error Unsupported VERA_VERSION
+#endif
+
 volatile byte vera_data1 @ $9f23
 volatile byte vera_data2 @ $9f24
 volatile byte vera_ctrl @ $9f25
@@ -23,10 +49,19 @@ asm void set_vera_layer_internal(pointer.vera_layer_setup ax, byte y) {
     sta __reg
     stx __reg+1
     stz vera_ctrl
+#if VERA_VERSION == 7
     lda $14
     sta vera_addr_hi
     stz vera_addr_mi
     sty vera_addr_lo
+#elseif VERA_VERSION == 8
+    lda $1F
+    sta vera_addr_hi
+    sty vera_addr_mi
+    stz vera_addr_lo
+#else
+#error Unsupported VERA_VERSION
+#endif
     ldy #0
     __set_layer_internal_loop:
     lda (__reg),y
@@ -37,13 +72,25 @@ asm void set_vera_layer_internal(pointer.vera_layer_setup ax, byte y) {
     ? rts
 }
 
-asm void set_vera_layer0(pointer.vera_layer_setup ax) {
+asm void set_vera_layer1(pointer.vera_layer_setup ax) {
+#if VERA_VERSION == 7
     ? ldy #0
+#elseif VERA_VERSION == 8
+    ? ldy #$20
+#else
+#error Unsupported VERA_VERSION
+#endif
     ? jmp set_vera_layer_internal
 }
 
-asm void set_vera_layer1(pointer.vera_layer_setup ax) {
-    ? ldy #0
+asm void set_vera_layer2(pointer.vera_layer_setup ax) {
+#if VERA_VERSION == 7
+    ? ldy #$10
+#elseif VERA_VERSION == 8
+    ? ldy #$30
+#else
+#error Unsupported VERA_VERSION
+#endif
     ? jmp set_vera_layer_internal
 }
 
@@ -87,7 +134,7 @@ inline void vera_upload(int24 address, pointer source, byte size) {
         ? ldy #0
         __vera_upload_loop:
         ? lda (__reg),y
-        ? sta vera_data1
+        ! sta vera_data1
         ? iny
         ? cpy size
         ? bne __vera_upload_loop
@@ -101,3 +148,13 @@ struct vera_sprite_data {
     byte ctrl0
     byte ctrl1
 }
+
+inline asm void set_ram_bank(byte a) {
+    ! STA $9F61
+    ? RTS
+}
+
+inline asm void set_rom_bank(byte a) {
+    ! STA $9F60
+    ? RTS
+}

include/x16_joy.mfk

@@ -0,0 +1,89 @@
+
+void x16_reset_joy() {
+	input_dx = 0
+	input_dy = 0
+	input_a = 0
+	input_b = 0
+	input_x = 0
+	input_y = 0
+	input_start = 0
+	input_select = 0
+	input_l = 0
+	input_r = 0
+}
+
+alias reset_joy = x16_reset_joy!
+
+// TODO: be more controller-agnostic?
+
+// SNES:B NES:A keyboard:Ctrl
+alias input_b = input_btn
+
+// SNES:A
+byte input_a
+
+// SNES:X
+byte input_x
+
+// SNES:Y NES:B keyboard:Alt
+byte input_y
+
+// SNES/NES:Start keyboard:Enter
+byte input_start
+
+// SNES/NES:Select keyboard:Space
+byte input_select
+
+// SNES:L
+byte input_l
+
+// SNES:R
+byte input_r
+
+void read_joy1() {
+    x16_reset_joy()
+    read_also_joy1()
+}
+void read_joy2() {
+    x16_reset_joy()
+    read_also_joy2()
+}
+asm void read_also_joy1() {
+    JSR $FF06
+    LDA $F1
+    BNE __read_also_joy1_skip
+    LDA $EF
+    JSR x16_joy_byte0
+    LDA $F0
+    JSR x16_joy_byte1
+__read_also_joy1_skip:
+    RTS
+}
+asm void read_also_joy2() {
+    JSR $FF06
+    LDA $F4
+    BNE __read_also_joy2_skip
+    LDA $F2
+    JSR x16_joy_byte0
+    LDA $F3
+    JSR x16_joy_byte1
+__read_also_joy2_skip:
+    RTS
+}
+
+void x16_joy_byte0(byte value) {
+	if value & 8 == 0 { input_dy -= 1 }
+	if value & 4 == 0 { input_dy += 1 }
+	if value & 2 == 0 { input_dx -= 1 }
+	if value & 1 == 0 { input_dx += 1 }
+	if value & 16 == 0 { input_start += 1 }
+	if value & 32 == 0 { input_select += 1 }
+	if value & 64 == 0 { input_y += 1 }
+	if value & 128 == 0 { input_b += 1 }
+}
+void x16_joy_byte1(byte value) {
+	if value & 16 == 0 { input_r += 1 }
+	if value & 32 == 0 { input_l += 1 }
+	if value & 64 == 0 { input_x += 1 }
+	if value & 128 == 0 { input_a += 1 }
+}

include/x16_joy1_default.mfk

@@ -0,0 +1,5 @@
+// set X16 joypad in port 1 as the default
+
+import x16_joy
+
+alias read_joy = read_joy1

include/x16_kernal.mfk

@@ -0,0 +1,2 @@
+// Let's be lazy:
+import c64_kernal

mkdocs.yml

@@ -42,6 +42,7 @@ nav:
     - C64-only modules: stdlib/c64.md
     - NES-only modules: stdlib/nes.md
     - Game Boy–only modules: stdlib/gb.md
+    - X16–only modules: stdlib/x16.md
   - Implementation details:
     - Calling convention: abi/calling-convention.md
     - Generated labels: abi/generated-labels.md