Example 16. Using Recursive Macros

fact    .macro  N,loc
        .if     N < 2
        MOV     #1,&loc
        .else
        MOV     #N,&loc
        .eval   N-1,N
        fact1
        .endif
        .endm

fact1   .macro
        .if     N > 1
        MOV     #N,R12       ; Assume MPY requires args to be in R12,R13
        MOV     &loc,R13
        CALL    MPY
        MOV     R12,&loc     ; Assume MPY returns product in R12
        .eval   N - 1,N
        fact1
        .endif

        .endm

        .global fact_result
        .global MPY

        fact    5,fact_result