Macro parameters ignore conditionals

[thrust26]

The following code does not assemble:

CHECK = 0

  MAC TEST
      .byte {1}
    IF CHECK > 0
      .byte {2}
    ENDIF
  ENDM

  ORG $f000

  TEST 1

testmac.asm (12): error: Not enough args passed to Macro.

Unrecoverable error(s) in pass, aborting assembly!
Complete.

It seems like the CHECK condition is not evaluated before checking the number of parameters required by the macro.

[andrew-davie]

I have found that my understanding of macros in DASM seems closest to reality when I think of macros as purely a text-substitution engine. It does not know of or understand the values of things. This is why it seems impossible to use values of variables inside macros, in any form. You get the text label of things, and only that. In other words, the macro first plonks down the text according to various substitution rules ({1} etc) and only after the macro is completed, then the resultant code is assembled. That is my current understanding of how to work with macros, anyway.

[Rhialto]

On Mon 09 Mar 2020 at 00:55:34 -0700, andrew-davie wrote: I have found that my understanding of macros in DASM seems closest to reality when I think of macros as **purely** a text-substitution engine. It does not know of or understand the **values** of things.

I think that is pretty much true for all macro assemblers I have ever used. Sometime, you can do a bit of "extra" stuff, such as getting at the number of parameters that were passed, or iterating over all parameters in turn, or testing if a parameter is the empty string or equal to some string or another... but that never abandons the principle that everything is just text substitution. Take this macro from a program in MACRO-11 (the main assembler for the PDP-11): .macro save things .irp x,<things> .if b x ; if blank, just decrease stack pointer, ; don't really store anything tst -(p) .iff ; "if false", meaning "else" .if idn x,#0 ; if #0, use the clr instruction ; instead of really moving anything clr -(sp) .iff mov x,-(sp) .endc .endc .endr .endm where .irp is a repeating loop, setting 'x' in turn to the values in <things>, which is a parameter to the macro. You use it for instance like save <r0,,#0,#2> which would generate code like mov r0,-(sp) tst -(sp) clr -(sp) mov #2,-(sp) which in turn saves the values in register 0, and the immediate values #1 and #2. MACRO11 even has a directive .NTYPE, which you give some string and it parses it as an operand, and sets a variable to the addressing mode it found. So you can use .if conditions in your macro; the macro is still just string manipulation, but the .NTYPE directive gives you just that extra bit of power to optimize your macro for various types of arguments.

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