|Adding block scopes to an assembly language email@example.com (Derek Ross) (2000-04-27)|
|Re: Adding block scopes to an assembly language firstname.lastname@example.org (Derek Ross) (2000-04-29)|
|Re: Adding block scopes to an assembly language email@example.com (Randall Hyde) (2000-04-29)|
|Re: Adding block scopes to an assembly language firstname.lastname@example.org (2000-05-01)|
|From:||"Randall Hyde" <email@example.com>|
|Date:||29 Apr 2000 23:55:15 -0400|
> I'm interested in giving block scopes to an assembly language, in
> particular for the ADSP2181 dsp.
Can't help you with that, but you might want to take a look at the
way I did it in HLA (the High Level Assembler) for the 80x86.
see http://webster.cs.ucr.edu for details.
.. snipped examples..
> But my question is, "what is the proper way to go about this?" I could
> start hacking away with a C compiler, but I suspect that would take much
> longer than is necessary.
> Are LEX and YACC the way to go? If yes, what would be overall scheme to
> accomplish this?
I'm assuming (unlike John's reply) that you don't have access to the
sources for the existing assembler. Let me make a few suggestions
about your two choices above.
(1) I wrote HLA using Flex and Bison. That was the biggest mistake I
ever made. Now HLA's source code is not a wonder of software
engineering (in fact, it's a prototype and, by definition, awful);
however, I could have done much more using only C/C++ with half the
(2) Flex and Bison are affectionately known as "the 80% solution." In
my experience, that other 20% really kills you. You will be able to
hack together a quick program that does what you want using Flex and
Bison (i.e., a prototype). But if you want to make it robust, have
good error checking, etc., forget Flex and Bison; IMO they're more
trouble than they're worth.
(3) Plan on extending your language. Today you need BEGIN and END.
Tomorrow you will probably want to enhance it a bit. Whatever you do,
don't cave in to the "Quick & Dirty" siren call; you will definitely
regret this later. E.g., the HLA system contains between 150,000 to
200,000 lines of source code; I'd originally expected it to be on the
order of 50,000 lines. Obviously, things got out of control.
(4) I don't know how you debug your code, but do keep in mind that
your preprocessing is probably going to mess up the symbols that are
fed as input to a symbolic debugger (assuming you use one). I'd
strongly recommend using named blocks, e.g.,
and merging the block identifier ("thisblock" in the example above)
with the new ID you generate. This will help reduce the debugging
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