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151 lines
6.6 KiB
Markdown
151 lines
6.6 KiB
Markdown
[](https://saythanks.io/to/irmen)
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[](https://travis-ci.org/irmen/prog8)
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[](https://prog8.readthedocs.io/)
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Prog8 - Structured Programming Language for 8-bit 6502/65c02 microprocessors
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============================================================================
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*Written by Irmen de Jong (irmen@razorvine.net)*
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*Software license: GNU GPL 3.0, see file LICENSE*
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This is a structured programming language for the 8-bit 6502/6510/65c02 microprocessor from the late 1970's and 1980's
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as used in many home computers from that era. It is a medium to low level programming language,
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which aims to provide many conveniences over raw assembly code (even when using a macro assembler).
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Documentation
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-------------
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Full documentation (syntax reference, how to use the language and the compiler, etc.) can be found at:
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https://prog8.readthedocs.io/
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What does Prog8 provide?
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------------------------
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- reduction of source code length over raw assembly
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- fast execution speed due to compilation to native assembly code. It's possible to write certain raster interrupt 'demoscene' effects purely in Prog8.
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- modularity, symbol scoping, subroutines
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- various data types other than just bytes (16-bit words, floats, strings)
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- Strings can contain excaped characters but also many symbols directly if they have a petscii equivalent, such as "♠♥♣♦π▚●○╳". Characters like ^, _, \, {, } and | are also accepted and converted to the closest petscii equivalents.
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- automatic static variable allocations, automatic string and array variables and string sharing
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- subroutines with input parameters and result values
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- high-level program optimizations
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- small program boilerplate/compilersupport overhead
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- Programs can be run multiple times without reloading because of automatic variable (re)initializations.
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- conditional branches
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- floating point operations (requires the C64 Basic ROM routines for this)
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- 'when' statement to provide a concise jump table alternative to if/elseif chains
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- many built-in functions such as ``sin``, ``cos``, ``rnd``, ``abs``, ``min``, ``max``, ``sqrt``, ``msb``, ``rol``, ``ror``, ``swap``, ``sort`` and ``reverse``
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- various powerful built-in libraries to do I/O, number conversions, graphics and more
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- convenience abstractions for low level aspects such as ZeroPage handling, program startup, explicit memory addresses
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- inline assembly allows you to have full control when every cycle or byte matters
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- supports the sixteen 'virtual' 16-bit registers R0 .. R15 from the Commander X16, and provides them also on the C64.
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- encode strings and characters into petscii or screencodes as desired (C64/Cx16)
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*Rapid edit-compile-run-debug cycle:*
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- use a modern PC to do the work on, use nice editors and enjoy quick compilation times
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- can automatically run the program in the Vice emulator after succesful compilation
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- breakpoints, that let the Vice emulator drop into the monitor if execution hits them
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- source code labels automatically loaded in Vice emulator so it can show them in disassembly
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*Two supported compiler targets* (contributions to improve these or to add support for other machines are welcome!):
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- "c64": Commodore-64 (6510 CPU = almost a 6502)
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- "cx16": [CommanderX16](https://www.commanderx16.com) (65c02 CPU)
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- If you only use standard kernal and prog8 library routines, it is possible to compile the *exact same program* for both machines (just change the compiler target flag)!
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Additional required tools
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-------------------------
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[64tass](https://sourceforge.net/projects/tass64/) - cross assembler. Install this on your shell path.
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A recent .exe version of this tool for Windows can be obtained from my [clone](https://github.com/irmen/64tass/releases) of this project.
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For other platforms it is very easy to compile it yourself (make ; make install).
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A **Java runtime (jre or jdk), version 11 or newer** is required to run a prepackaged version of the compiler.
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If you want to build it from source, you'll need a Java SDK + Kotlin 1.3.x SDK (or for instance,
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IntelliJ IDEA with the Kotlin plugin).
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It's handy to have an emulator (or a real machine perhaps!) to run the programs on. The compiler assumes the presence
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of the [Vice emulator](http://vice-emu.sourceforge.net/) for the C64 target,
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and the [x16emu emulator](https://github.com/commanderx16/x16-emulator) for the CommanderX16 target.
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Example code
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------------
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This code calculates prime numbers using the Sieve of Eratosthenes algorithm::
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%import textio
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%zeropage basicsafe
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main {
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ubyte[256] sieve
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ubyte candidate_prime = 2 ; is increased in the loop
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sub start() {
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sys.memset(sieve, 256, false) ; clear the sieve
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txt.print("prime numbers up to 255:\n\n")
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ubyte amount=0
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repeat {
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ubyte prime = find_next_prime()
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if prime==0
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break
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txt.print_ub(prime)
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txt.print(", ")
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amount++
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}
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txt.nl()
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txt.print("number of primes (expected 54): ")
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txt.print_ub(amount)
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txt.nl()
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}
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sub find_next_prime() -> ubyte {
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while sieve[candidate_prime] {
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candidate_prime++
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if candidate_prime==0
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return 0 ; we wrapped; no more primes
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}
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; found next one, mark the multiples and return it.
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sieve[candidate_prime] = true
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uword multiple = candidate_prime
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while multiple < len(sieve) {
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sieve[lsb(multiple)] = true
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multiple += candidate_prime
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}
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return candidate_prime
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}
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}
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when compiled an ran on a C-64 you'll get:
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One of the included examples (wizzine.p8) animates a bunch of sprite balloons and looks like this:
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Another example (cube3d-sprites.p8) draws the vertices of a rotating 3d cube:
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If you want to play a video game, a fully working Tetris clone is included in the examples:
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There are a couple of examples specially made for the CommanderX16 compiler target.
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For instance here's a well known space ship animated in 3D with hidden line removal,
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in the CommanderX16 emulator:
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