Chapter
5. Macros
Example
1:
Nested I
RPC
The following macro definition contains a nested
IRPC
directive. Notice that the third operand
of
the outer
macro becomes the character string for the
I
RPC:
MOVE
MACRO
IRPC
LHLD
SHLD
ENDM
ENDM
X,Y,Z
PARAM,Z
X&&PARAM
Y&&PARAM
Assume that the program contains the
call
MOVE
SRC,DST,123. The third parameter
of
this
call
is
passed to
the
I
RPC.
This has the same effect
as
coding I
RPC
PARAM,123.
When
expanded, the
MOVE
macro generates
the following source code:
LHLD
SRC1
SHLD
DST1
LHLD
SRC2
SHLD DST2
LHLD
SRC3
SHLD
DSn
Notice the
use
of
concatenation to form labels
in
this example.
Example
2:
Nested Macros U,ed to Generate
DB
Directives
This example generates a number of
DB
0 directives, each with its own label.
Two
macros are
used
for this
purpose:
INC
and BLOCK. The
INC
macro
is
defined
as
follows:
INC
$
SAVE
GEN
F1
&F2:
$ RESTORE
MACRO
DB
ENDM
F1,F2
o ;GENERATE LABELS & DB's
The
BLOCK
macro, which accepts the number of DB's to
be
generated
(NUMB)
and a
label
prefix (PREFIX),
is
defined
as
follows:
$
BLOCK
MACRO
SAVE NOGEN
COUNT
COUNT
SET
REPT
SET
INC
ENDM
$ RESTORE
ENDM
NUMB,PREFIX
o
NUMB
COUNT+1
PREFIX,%COUNT ;NESTED
MACRO
CALL
S-17
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