Re: Question about writing assemblers

In comp.compilers maliha032@yahoo.com (Maliha Samad) writes:


>I am very confused as to whether I should write a hand coded assembler
>or should I use the existing tools like lex and yacc.


I've been working on the GNU assembler for several years.


I've never felt a need to use lex. Most assemblers accept a simple
line oriented syntax, and it is normally easy to pick out operands.


Only once have I seen a reason to use yacc. That was for the m68k
operand syntax. The m68k has a wide range of operand types, and for
historical reasons the GNU assembler supports two different operand
syntaxes. The original code to recognize both syntaxes was complex;
changing to yacc (work which I didn't start) made it quite a bit
clearer. Even then, the yacc parser was applied only to the operands;
picking out the operands themselves was done by a simpler procedure.


Of course what you should do depends upon the syntax you have to
parse.
--
Ian Taylor | ian@airs.com

Return to the comp.compilers page.
Search the comp.compilers archives again.