[SOLVED] NASM - empty macro with 2 parameters? What register is represented by parameter

NASM - empty macro with 2 parameters? What register is represented by parameter_m?

I'm in the process of porting NASM code to MASM, and I'm stuck on a NASM empty macro with 2 parameters and register usage with the _m suffix.

example code:

;register defines
%define arg0   rcx
%define arg4   r12
%define tmp4   r14
%define len    arg0
%define dest1  arg4
%define dest2  tmp4
%define PS     8

;empty macro
%macro  SLDR 2
%endmacro
%define SSTR SLDR

; example usage in code:

        SLDR    len, len_m
        sub     len, 16
        SSTR    len_m, len
        jl      .return0

;...

        SLDR    dest1, dest1_m
        mov     dest2, [dest1+PS]
        SSTR    dest2_m, dest2
        mov     dest1, [dest1]
        SSTR    dest1_m, dest1

I assume the _m parameters are macro generated names, but what register(s) do they represent (assuming they are not on the stack)?

Solution

In this case:

parameter_m is just a literal argument passed into the macro.
The macro doesn’t know or care what register parameter_m is unless you define it elsewhere.

If parameter_m is not defined, then NASM throws an error like:
error: symbol `parameter_m' undefined. (Or it would if your macro used this token as an operand to an instruction, rather than in a %define or stringifying it or something. As is, it assembles cleanly since the empty macro does nothing with it.)