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cassemblymacrosgnu-assembler

Calling a table of function using repeat blocks or macros in GNU assembly

If I wanted to generate code that looks like this:

CALL FUNC0
CALL FUNC1
CALL FUNC2
CALL FUNC3
CALL FUNC4
CALL FUNC5
...
CALL FUNC19

How can I use a repeat block generate such code, using something similar to the code below:

.equ SYMBOL, 0
.rept 20
   CALL FUNC(SMYBOL)
   .equ SYMBOL, (SYMBOL+1)
.endr

Macros are fine too.

I'd like to know how to do this in C as well.

Solution

  • You can use a macro do this:

    .altmacro
.macro call_funcs count
    .if \count
        call_funcs %(count-1)
    .endif
    CALL    FUNC\count
.endm

call_funcs 20

    The .altmacro directive enables the use of % to evaluate count - 1 before passing recursively as a macro argument. Otherwise you get CALL FUNC20-1-1-1-1 which not what you want.

    As far as I know there's no way to what you want in C. For that I would write a program that generates the C code you need.