prog8/README.md
2019-04-12 22:34:43 +02:00

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Prog8 - Structured Programming Language for 8-bit 6502/6510 microprocessors
===========================================================================
*Written by Irmen de Jong (irmen@razorvine.net)*
*Software license: GNU GPL 3.0, see file LICENSE*
This is a structured programming language for the 8-bit 6502/6510 microprocessor from the late 1970's and 1980's
as used in many home computers from that era. It is a medium to low level programming language,
which aims to provide many conveniences over raw assembly code (even when using a macro assembler):
- reduction of source code length
- easier program understanding (because it's higher level, and more terse)
- option to automatically run the compiled program in the Vice emulator
- modularity, symbol scoping, subroutines
- subroutines have enforced input- and output parameter definitions
- various data types other than just bytes (16-bit words, floats, strings, 16-bit register pairs)
- automatic variable allocations, automatic string variables and string sharing
- constant folding in expressions (compile-time evaluation)
- automatic type conversions
- floating point operations
- abstracting away low level aspects such as ZeroPage handling, program startup, explicit memory addresses
- breakpoints, that let the Vice emulator drop into the monitor if execution hits them
- source code labels automatically loaded in Vice emulator so it can show them in disassembly
- conditional gotos
- various code optimizations (code structure, logical and numerical expressions, ...)
It is mainly targeted at the Commodore-64 machine at this time.
Documentation is online at https://prog8.readthedocs.io/
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).
A **Java runtime (jre or jdk), version 8 or newer** is required to run the packaged compiler.
If you want to build it from source, you'll need a Kotlin 1.3 SDK as well (or for instance,
IntelliJ IDEA with the Kotlin plugin).
It's handy to have a C-64 emulator or a real C-64 to run the programs on. The compiler assumes the presence
of the [Vice emulator](http://vice-emu.sourceforge.net/)
Example code
------------
This code calculates prime numbers using the Sieve of Eratosthenes algorithm::
%import c64utils
%zeropage basicsafe
~ main {
ubyte[256] sieve
ubyte candidate_prime = 2
sub start() {
memset(sieve, 256, false)
c64scr.print("prime numbers up to 255:\n\n")
ubyte amount=0
while true {
ubyte prime = find_next_prime()
if prime==0
break
c64scr.print_ub(prime)
c64scr.print(", ")
amount++
}
c64.CHROUT('\n')
c64scr.print("number of primes (expected 54): ")
c64scr.print_ub(amount)
c64.CHROUT('\n')
}
sub find_next_prime() -> ubyte {
while sieve[candidate_prime] {
candidate_prime++
if candidate_prime==0
return 0
}
sieve[candidate_prime] = true
uword multiple = candidate_prime
while multiple < len(sieve) {
sieve[lsb(multiple)] = true
multiple += candidate_prime
}
return candidate_prime
}
}
when compiled an ran on a C-64 you'll get:
![c64 screen](docs/source/_static/primes_example.png)
One of the included examples (wizzine.p8) animates a bunch of sprite balloons and looks like this:
![wizzine screen](docs/source/_static/wizzine.png)
Another example (cube3d-sprites.p8) draws the vertices of a rotating 3d cube:
![cube3d screen](docs/source/_static/cube3d.png)
If you want to play a video game, a fully working Tetris clone is included in the examples:
![tehtriz_screen](docs/source/_static/tehtriz.png)