Motorola HC12 - Manual (Page 207)

Macros
Macro Expansion
MCUez HC12 Assembler User’s Manual
MOTOROLA Macros 207
This macro is called in the application:
clear temporary
clear data
The two macro calls of clear are expanded this way:
clear temporary
LDX temporary
LDAB #16
_00001LOOP:CLR 0,X
INX
DECB
BNE _00001LOOP
clear data
LDX data
LDAB #16
_00002LOOP:CLR 0,X
INX
DECB
BNE _00002LOOP
9.8 Macro Expansion
When the assembler reads a statement in a source program that calls a
previously defined macro, it processes the call as described here.
The symbol table is searched for the macro name. If it is not in the symbol table,
an undefined symbol error message is issued.
The rest of the line is scanned for arguments. Any argument in the macro call is
saved as a literal or null value in one of the 35 possible parameter fields. When
the number of arguments in the call is less than the number of parameters used
in the macro, the arguments that have not been defined at invocation time are
initialized with ““ (empty string).
Starting with the line following the MACRO directive, each line of the macro
body is saved and is associated with the named macro. Each line is retrieved in
turn, with parameter designators replaced by argument strings or
assembler-generated label strings.
Once the macro is expanded, the source lines are evaluated and object code is
produced.