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133 lines
5.0 KiB
Markdown
133 lines
5.0 KiB
Markdown
[](https://saythanks.io/to/irmen)
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[](https://travis-ci.org/irmen/prog8)
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Prog8 - Structured Programming Language for 8-bit 6502/6510 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 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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- reduction of source code length
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- easier program understanding (because it's higher level, and way more compact)
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- modularity, symbol scoping, subroutines
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- subroutines have enforced input- and output parameter definitions
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- various data types other than just bytes (16-bit words, floats, strings, 16-bit register pairs)
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- automatic variable allocations, automatic string variables and string sharing
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- constant folding in expressions (compile-time evaluation)
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- conditional branches
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- when statement to provide a 'jump table' alternative to if/elseif chains
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- structs to group together sets of variables and manipulate them at once
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- automatic type conversions
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- floating point operations (uses the C64 Basic ROM routines for this)
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- abstracting away low level aspects such as ZeroPage handling, program startup, explicit memory addresses
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- various code optimizations (code structure, logical and numerical expressions, unused code removal...)
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- inline assembly allows you to have full control when every cycle or byte matters
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Rapid edit-compile-run-debug cycle:
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- use modern PC to work on
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- quick compilation times (less than 1 second)
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- option to automatically run the program in the Vice emulator
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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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- the compiler includes a virtual machine that can execute compiled code directy on the
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host system without having to actually convert it to assembly to run on a real 6502.
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This allows for very quick experimentation and debugging
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It is mainly targeted at the Commodore-64 machine at this time.
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Contributions to add support for other 8-bit (or other?!) machines are welcome.
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Documentation is online at https://prog8.readthedocs.io/
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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 8 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 a C-64 emulator or a real C-64 to run the programs on. The compiler assumes the presence
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of the [Vice emulator](http://vice-emu.sourceforge.net/)
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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 c64utils
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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
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sub start() {
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memset(sieve, 256, false)
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c64scr.print("prime numbers up to 255:\n\n")
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ubyte amount=0
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while true {
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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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c64scr.print_ub(prime)
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c64scr.print(", ")
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amount++
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}
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c64.CHROUT('\n')
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c64scr.print("number of primes (expected 54): ")
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c64scr.print_ub(amount)
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c64.CHROUT('\n')
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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
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}
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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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