I recently updated my pas6502 Pascal -> 6502 compiler again. It now supports c64, c128, vic20, BBC micro, Atari 8-bit, and soon NES (hopefully).
Syntaxerrorsoftware.itch.io/pas6502

Thanks for the info mate
cheers,
Paul

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

cheers,
Paul

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 ...

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 ...

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:
http://forum.6502.org/images ...

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):

a := -(x=0)

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

x := x*(1+2*(x<0))

Just ...

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

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.

What does

x := (x<0)*x*2+x
compile to?

That currently compiles to:
main:
:loadIntRegMem(x,0)
:loadIntRegIm(0,1)
:cmpIntRegLss(0,1,0)
:loadIntRegMem(x,1)
:mulIntReg(0,1,0)
:loadIntRegIm(2,1)
:mulIntReg(0,1,0)
:loadIntRegMem(x,1)
:addIntReg(0,1,0)
:storeIntRegMem(0,x)
rts


:)

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 ...

Thanks for all the answers everyone, much appreciated

I think I'm good now

cheers,
Paul

As was already suggested, you can test for -1 before the division.
My question is, does the -1 result cause a problem with your program? In other words, does your program require symetrical integer division or can you use floored integer division?
With floored integer division, if the real result ...

I had a fiddle (not a short as your version) and got something to work:

.macro div2_16bit(address) {
// is the value -1 at the start?
lda address + 1
cmp #255
bne divBy2
lda address + 0
cmp #255
bne divBy2

// yes, so set to zero and exit
lda #0
sta address + 1
sta address + 0
jmp done ...

Thanks Mike B

That seems to work ok if the value is -1 before the macro, but if the value is -2 before the macro then the result becomes 0 right away instead of -1 as I would have expected.

cheers,
Paul