Hi all,
I'd thought I'd mention that I'm working on a project (part fun/learning/useful) called Pas6502 which will compile a dialect of Pascal into 6502 assembly code (using Kick Assembler macros and asm code). I will be starting with the C64.

I know there have been others, but I wanted to do this myself too

I have made a start where I can parse expressions using standard Pascal syntax, or expressions including mixed maths & boolean logic for tricky equations like the Dirac delta function (one line):



or the absolute value function (definitely tricky code!):



Which currently produces this code:


I will be adding in expression simplification too which will include power of 2 div/mull -> shifts/shifts+adds.

Internally, I will be representing False = 0 and True = -1, but any value <> 0 will also equate to True so I will be able to things like;



I am also posting on twitter:
https://twitter.com/SyntaxErrorSoft/status/1063554525586321409


cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

What does
compile to?

_________________
Got a kilobyte lying fallow in your 65xx's memory map? Sprinkle some VTL02C on it and see how it grows on you!

Mike B. (about me) (learning how to github)

That currently compiles to:

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

I've now added some optimizations like simplifying to a numerical value where possible, division with a power of 2 to a shift, and multiplication to shifts & additions. Will do * 0, * 1, + 0 optimizations too amongst others.

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

How were you doing it before your optimization?

_________________
Got a kilobyte lying fallow in your 65xx's memory map? Sprinkle some VTL02C on it and see how it grows on you!

Mike B. (about me) (learning how to github)

I was just parsing the expression into postfix format using an expression tree and not optimising it before...

Is that what you meant?
cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

Just so ya know, in Pascal, those aren't legal expressions.

Pascal is not C where boolean expressions are actually just integer expression checking for zero, boolean is a "real" type in Pascal, and there's no language construct that casts booleans to integers. You could write one of course, but it's not in the stock language.

I know, that's why I wrote this:


I wanted to give the programmer the freedom of using both Standard Pascal and the mixed version

cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

More #Pas6502 compiler progress...can now do basic math, store values into variables and absolute addresses (1 or 2 byte) [including arrays], and Poke() command added. More optimisation needed, but am very happy <committing to version control now lol>

Input example:


Output example (copied from the ASM window):

cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

I've now added if and while statements to #Pas6502, and here is the obligatory infinite loop incrementing the border color lol

If anyone is wondering, I've been basing my code on the classic "Let's build a compiler" tutorial series by Jack W. Crenshaw here:
http://www.penguin.cz/~radek/book/lets_build_a_compiler.pdf





cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

What are you writing in in and in what environment? e.g. would I be able to run it under Linux using vim to edit files? Or do you think it would ever work on a 6502 hosted system?

Cheers,

-Gordon

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--
Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/

I'm writing it using Embarcadero Delphi.

I guess it would run under Wine in Linux, and you could use any text editor to create the source code files, but currently, you would have to load it into the compiler window (or copy/paste) prior to compiling it to a .prg file.

It uses kick assembler (runs using Java) to assemble the generated assembly source code to a C64 .prg file.

cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls

Just to note, it looks like there's an updated version:

damn if this worked for the 65816 then it could maybe be possible to port ORCA-C to a more generic system instead of being Apple IIgs specific

Interesting, I'll have a look at the 65816 CPU to see what that is like for possibly adding to Pas6502

cheers,
Paul

_________________
"The plastic veneer of civilization is easily melted in the heat of the moment" - Paul Nicholls