III.11.8 Nested Macro Definitions

A macro body may also contain further macro definitions. However, these nested macro definitions aren't valid until the enclosing macro has been expanded! That means, the enclosing macro must have been called, before the nested macros can be called.

Example 1:

A macro, which can be used to define macros with arbitrary names, may look as follows:

        DEFINE MACRO MACNAME
        MACNAME MACRO
        DB 'I am the macro &MACNAME.'
        ENDM
        ENDM

In order not to overload the example with "knowhow", the nested macro only introduces itself kindly with a suitable character string in ROM. The call

        DEFINE Obiwan

would define the macro

        Obiwan MACRO
        DB 'I am the macro Obiwan.'
        ENDM

and the call

        DEFINE Skywalker

would define the following macro:

        Skywalker MACRO
        DB 'I am the macro Skywalker.'
        ENDM

Example 2:

A macro is to insert a variable number of NOPs into the program. For this, a macro with a nested REPT block seems to be best-suited:

        REPEAT MACRO NOPS
        REPT NOPS
        NOP
        ENDM
        ENDM

The macro call

        REPEAT 4

results in something like that:

        Line  I  Addr  Code            Source

           9+ 1        N      0004     REPT 4
          10+ 1                        NOP
          11+ 1                        ENDM
          12+ 2  0000  00              NOP
          13+ 2  0001  00              NOP
          14+ 2  0002  00              NOP
          15+ 2  0003  00              NOP