Macro Directives
Macro directives enable a block of source statements to be named, and then that name to be
re-used in the source file to represent the statements. During assembly, the Cross Assembler auto
-
matically replaces each occurrence of the macro name with the statements in the macro definition.
A macro can be defined at any place in the source file as long as the definition precedes the first
source line that calls this macro. In the macro definition, the macro to be defined may refer to other
macros which have been previously defined. The Cross Assembler supports a maximum of 7 nest
-
ing levels.
Syntax
name MACRO [dummy-parameter [, ...]]
statements
ENDM
The Cross Assembler supports a directive LOCAL for the macro definition.
Syntax
name LOCAL dummy-name [, ...]
·
Description
The LOCAL directive defines symbols available only in the defined macro. It must be the first line
following the MACRO directive, if it is present. The dummy-name is a temporary name that is re
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placed by a unique name when the macro is expanded. The Cross Assembler creates a new ac
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tual name for dummy-name each time the macro is expanded. The actual name has the form
??digit, where digit is a hexadecimal number within the range from 0000 to FFFF. A label
should be added to the LOCAL directive when labels are used within the MACRO/ENDM block.
Otherwise, the Cross Assembler will issue an error if this MACRO is referred to more than once in
the source file.
In the following example, tmp1 and tmp2 are both dummy parameters, and are replaced by ac-
tual parameters when calling this macro. label1 and label2 are both declared LOCAL, and
are replaced by ??0000 and ??0001 respectively at the first reference, if no other MACRO is re-
ferred. If no LOCAL declaration takes place, label1 and label2 will be referred to labels, simi-
lar to the declaration in the source program. At the second reference of this macro, a multiple
define error message is displayed.
Delay MACRO tmp1, tmp2
LOCAL label1, label2
mov a, 70h
mov tmp1, a
label1:
mov tmp2, a
label2:
clr wdt1
clr wdt2
sdz tmp2
jmp label2
sdz tmp1
jmp label1
ENDM
74
Cost-Effective I/O Type MCU
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