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This item is extracted from IBM PC Assembly Language: A Guide for
Programmers Page 43
Leo J. Scanlon

The EXITM Pseudo-Op

The EXITM pseudo-op makes the macro expansion terminate early, based on the
outcome of a preceding test.  For instance, recall the ALLOCATE macro that
we defined with the REPT pseudo-op.  You might like to redefine this macro so
that the assembler only allocates the table space if the LENGTH parameter is
less than 50.  A macro that makes this determination is:

ALL_LT_50   MACRO  LENGTH
            LOCAL  OKAY
VALUE       =      0
            MOV    AX,LENGTH
            CMP    AX,50             ;Is LENGTH < 50
            JB     OKAY
            EXITM                    ; If not, exit
OKAY:       REPT   LENGTH            ; If so, allocate the table
VALUE       =      VALUE+1
            DB     VALUE
            ENDM
 Laurence Leff, Ph.D               |A job is like sex, when you do it for money
CS,SMU, Dallas, Texas 75275-0122,  |You take away all the fun.
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