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202 lines
9.5 KiB
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202 lines
9.5 KiB
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*************************************
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What is Prog8?
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*************************************
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This is a compiled programming language targeting the 8-bit 6502 CPU family.
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The language aims to provide many conveniences over raw assembly code (even when using a macro assembler),
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while still being low level enough to create high performance programs.
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They targeted CPUs are the `6502 <https://en.wikipedia.org/wiki/MOS_Technology_6502>`_ /
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`6510 <https://en.wikipedia.org/wiki/MOS_Technology_6510>`_ /
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`65c02 <https://en.wikipedia.org/wiki/MOS_Technology_65C02>`_ microprocessors.
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They are from the late 1970's and early 1980's and was used in many home computers from that era,
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such as the `Commodore 64 <https://en.wikipedia.org/wiki/Commodore_64>`_.
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You can compile programs for various machines that are built in into the compiler:
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* Commander X16 (with 65c02 cpu, 65816 cpu specifics are currently not supported by prog8 itself)
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* Commodore 64
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* Commodore 128 (limited support)
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* Commodore PET (limited support)
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* any other 65(C)02 target machine or setup can be configured to a great extent in a user written configuration file.
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There are some examples included for the Atari 800 XL, NEO6502, Foenix F256, and such.
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* some users have been experimenting with a NES and a C64 OS target as well.
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Some language features are mentioned below, and you can also read :ref:`comparingprog8` if you
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want to quickly read about how Prog8 compares to well-known other languages.
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Community
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^^^^^^^^^
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Most of the development on Prog8 and the use of it is currently centered around
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the `Commander X16 <https://www.commanderx16.com/>`_ retro computer.
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However, the other compiler targets are also still worked on, most notably the C64 target where it all started with!
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The X16 `Discord server <https://discord.gg/nS2PqEC>`_ contains a small channel
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dedicated to Prog8. Besides that, you can use the issue tracker on github for questions or problems or contributions.
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Want to buy me a coffee or a pizza perhaps?
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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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.
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If you like Prog8, and think it's worth a nice cup of hot coffee or a delicious pizza,
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you can help me out a little bit over at https://ko-fi.com/irmen or https://paypal.me/irmendejong .
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.. image:: _static/cube3d.png
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:width: 33%
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:alt: 3d rotating sprites
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.. image:: _static/wizzine.png
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:width: 33%
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:alt: Simple wizzine sprite effect
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.. image:: _static/tehtriz.png
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:width: 33%
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:alt: Fully playable tetris clone
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.. image:: _static/rrgame.png
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:width: 33%
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:alt: BoulderDash(tm) clone for the X16
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.. image:: _static/x16paint.png
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:width: 33%
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:alt: Paint program for the X16
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.. image:: _static/x16chess.png
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:width: 33%
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:alt: Chess program for the X16
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Language Features
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^^^^^^^^^^^^^^^^^
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- it is a cross-compiler running on modern machines (Linux, MacOS, Windows, ...)
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- the compiled programs run very fast, because compilation to highly efficient native machine code.
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- code often is smaller and faster than equivalent C code compiled with CC65 or even LLVM-MOS
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- provides a convenient and fast edit/compile/run cycle by being able to directly launch
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the compiled program in an emulator and provide debugging information to this emulator.
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- the language looks like a mix of Python and C so should be quite easy to learn
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- Modular programming, scoping via module source files, code blocks, and subroutines. No need for forward declarations.
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- Provides high level programming constructs but at the same time stay close to the metal;
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still able to directly use memory addresses and ROM subroutines,
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and inline assembly to have full control when every register, cycle or byte matters
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- Variables are all allocated statically, no memory allocation overhead
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- Variable data types include signed and unsigned bytes and words, arrays, strings.
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- Structs and typed pointers
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- Tight control over Zeropage usage
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- Programs can be restarted after exiting (i.e. run them multiple times without having to reload everything), due to automatic variable (re)initializations.
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- Programs can be configured to execute in ROM
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- Conditional branches for status flags that map 1:1 to processor branch instructions for optimal efficiency
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- ``when`` statement to avoid if-else chains
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- ``on .. goto`` statement for fast jump tables
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- ``in`` expression for concise and efficient multi-value/containment test
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- ``defer`` statement to help write concise and robust subroutine cleanup logic
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- Several specialized built-in functions, such as ``lsb``, ``msb``, ``min``, ``max``, ``rol``, ``ror``
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- Various powerful built-in libraries to do I/O, number conversions, graphics and more
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- Floating point math is supported on certain compiler targets.
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- Provides access to most Kernal ROM routines as external subroutine definitions you can call normally.
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- Strings can contain escaped 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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- Encode strings and characters into petscii or screencodes or even other encodings, as desired (C64/Cx16)
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- Automatic ROM/RAM bank switching on certain compiler targets when calling routines in other banks
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- Identifiers can contain Unicode Letters, so ``knäckebröd``, ``приблизительно``, ``見せしめ`` and ``π`` are all valid identifiers.
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- Subroutines can return more than one result value
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- Advanced code optimizations to make the resulting program smaller and faster
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- Supports the sixteen 'virtual' 16-bit registers R0 to R15 as defined on the Commander X16. You can look at them as general purpose global variables. These are also available on the other compilation targets!
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- On the Commander X16: Support for low level system features such as Vera Fx, which includes 16x16 bits multiplication in hardware and fast memory copy and fill.
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- 50 Kb of available program RAM size on the C64 by default; because Basic ROM is banked out altogether
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- Many library routines are available across compiler targets. This means that as long as you only use standard Kernal
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and core prog8 library routines, it is sometimes possible to compile the *exact same program* for different machines by just changing the compilation target flag.
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Code example
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------------
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Here is a hello world program::
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%import textio
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%zeropage basicsafe
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main {
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sub start() {
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txt.print("hello world i ♥ prog8\n")
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}
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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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bool[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, 0) ; 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 C64 you get this:
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.. image:: _static/primes_example.png
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:align: center
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:alt: result when run on C64
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when the exact same program is compiled for the Commander X16 target, and run on the emulator, you get this:
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.. image:: _static/primes_cx16.png
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:align: center
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:alt: result when run on CX16 emulator
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.. _downloading:
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Getting the software
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^^^^^^^^^^^^^^^^^^^^
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Usually you just download a fat jar of an official released compiler version, but you can also build it yourself from source.
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Detailed instructions on how to obtain a version of the compiler are in :ref:`building_compiler`.
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You can also read there what extra tools you need to get going.
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You may look for an **emulator** (or a real machine of course) to test and run your programs on.
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For the PET, C64 and C128 targets, the compiler assumes the presence of the `VICE emulator <http://vice-emu.sourceforge.net/>`_.
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If you're targeting the Commander X16 instead,
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download a recent emulator version for the CommanderX16, such as `x16emu <https://cx16forum.com/forum/viewforum.php?f=30>`_
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(preferred, this is the official emulator. If required, source code is `here <https://github.com/X16Community/x16-emulator/>`_.
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There is also `Box16 <https://github.com/indigodarkwolf/box16>`_ which has powerful debugging features.
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If multiple options are listed above, you can select which one you want to launch using the ``-emu`` or ``-emu2`` command line options.
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**Syntax highlighting:** for a few different editors, syntax highlighting definition files are provided.
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Look in the :source:`syntax-files <syntax-files>` directory in the github repository to find them.
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