Zilog Z8F0130 - Manual (Page 355)

UM013037-1212 Optional Macro Arguments
Zilog Developer Studio II – Z8 Encore!
User Manual
331
Optional Macro Arguments
A macro can be defined to handle omitted arguments using the IFMA (if macro argument)
conditional directive within the macro. The conditional directive can be used to detect if
an argument was supplied with the invocation.
Example
MISSING_ARG: MACRO ARG0,ARG1,ARG2

IFMA 2

LD ARG0,ARG1

ELSE

LD ARG0,ARG2

ENDIF

ENDMACRO MISSING_ARG
Invocation
MISSING_ARG R1, ,@R2 ; missing second arg
Result
LD R1,@R2
IFMA refers to argument numbers that are one based (that is, the first argument is numbered
one).
Exiting a Macro
The MACEXIT directive is used to immediately exit a macro. No further processing is per-
formed. However, the assembler checks for proper if - then conditional directives. A
MACEXIT directive is normally used to terminate a recursive macro.
The following example is a recursive macro that demonstrates using MAXEXIT to termi-
nate the macro.
Example
RECURS_MAC: MACRO ARG1,ARG2

IF ARG1==0

MACEXIT

ELSE

RECURS_MAC ARG1-1, ARG2

DB ARG2

ENDIF

ENDMACRO RECURS_MAC

RECURS_MAC 1, ’a’
Note: