Hello

I am currently in the process of making an assembler for the 6502 family and i do have a working in-dev version of it (only 6502 and 65C02 w/o Rockwell as of now tho).
And i am thinking of what syntax to support with it. For example some assemblers use ':' for labels whereas others dont.

What syntax do you think is more popular and does it even matter?
Also, what directives do you think are most useful to have? (apart from obvious things such as macros, labels & simple data)

It's your assembler - use the syntax you're most comfortable with.

I use as65 from the cc65 suite and my own assembler (a work in progress) is more or less compatible with that.

as65 defaults to needing :'s but there is a flag to make them optional, so it can assemble source designed for a different assembler. (Also see "Postel's Law")

As for directives - conditional assembly and include another file along with the ones you mentioned. I use a 'repeat' construct in some of my code to unwind a loop too, so that's handy for me, but for you? ....

There might be a 'but' or 'however' though and that's if you expect others to use it. That's a hard sell in my book, (e.g. will it run on MS Win, Linux, Mac, C64, X16, my Ruby system, and other comments along those lines are what you'll get), so I'd save yourself the stress and just do it your way.

-Gordon

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

Hm, yeah i probably should have a similar option.



I do have conditional assembly & file include directives supported yeah) I also implemented "regions" to separate label/macro lookup.
As for others using it, it is my hobby project but i am going to release it on github when i feel like it is in a presentable form so that if somebody would want to use it that would be nice. Its not my target though, im mostly making it as an exercise.
As for compatibility, i plan for it to be compiled for windows, linux & mac, it wouldn't be compatible with older systems tho because it relies on "modern"-ish C and flex & bison for parsing.

Personally I tend to use ca65, which also has some mode flags for slight syntax variation.

In the land of Acorn and the BBC Micro, there's BeebAsm which implements something like the assembler-embedded-in-Basic which the Beeb offers, so you get Basic programming and expression evaluation to add something a bit like macros.

But but but, can I go right against the flow and the probable consensus here? I came across the assembler syntax used by Acorn back in the day, and it's unusual but I think it just might be great.

Instead of the familiar 3 letter opcodes, which form into a nice orderly column, you get a mix of lengths because the addressing mode is appended, which actually adds form and structure, making it easier to see what's going on. There's also a really minimal syntax for conditional assembly:


The conditional syntax is an IF THEN, but also there's an ELSE form:

(I'm guessing CLR is a synonym for STZ, and / is a bitwise negation.)

Examples from the MASM sources themselves - it seems MASM is written in MASM.

Something I've just thought of - and this may be yout 'regions' here - as65 has a notion of a 'procedure' with .proc and .endproc and inside that area labels defined are local to that area. So you can have multiple .proc/.endproc's in the same file each using the same label names.

Also un-named labels:



and so on ...

The trouble is... it would just end up looking like my (currently) favourite assembler

-Gordon

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

Some sort of local labels can be useful, especially for very short jumps out of loops or back to the head, things which barely need a name, but have to have a label.

There will certainly be a variety of opinions, and every practising assembly coder is likely to have settled on a preference. (All the same, I'm supportive of a new project, to see what it might bring.)

Just my 2 cents so feel free to disagree, but I have always been strongly against this since it only really exists to make life easier for the assembler writer at the expense of making it slightly harder for the people using the assembler. It's easy though to see the temptation since LDA (foo+1),Y and LDA (foo)+1,Y are two different addressing modes but a pain to tell apart for the assembler author.

In my opinion, the place where an assembler really shines is it's macro system. as65 and macro assembler AS are both good in this regard, though I've tried to do things with both where the macros weren't sophisticated enough. For one project, I switched to NASM, an x86 assembler, for the macro functionality then assembled the result with a 6502 assembler. It might be worth it to compare the different macro systems (they vary a lot) and see how you would like your macros to work.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Thanks, I'll check it out!
Also, what do you think is the better way to treat indirect addressing syntax?

I currently do not allow bracketed expressions as the operand for indirect addressing, as it would be very confusing to distinguish between
where the operand is and the addressing mode is indirect, and where the operand is and the addressing mode is absolute.
Currently the assembler would expect any indirect addressed instruction (indirect only, indirect indexed and indexed indirect dont count) to not have any brackets in the expression.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

I used that as an example, i meant any expression in brackets in general.
Using other brackets for me would be problematic though, as my current syntax uses {} to explicitly specify bit width of a value.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Hm. Maybe i could use the C-style ":" to define bit width. I do not like/want to use the "<" for defining bit width as it is fairly limited and can be confused with bit shift operation and boolean relation.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?