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Chapter 10 Writing Assembler Control Statements
192 Conditional Assembly
Usage example
A source file that uses #ifdef and #ifndef is shown below.
The assembled list file is shown below.
The identifier VERSION is defined in line number 1. The replacement string is a null character. Since
VERSION has been defined, the #ifdef starting from line number 4 will assemble block 1 (line number
5 here), and will not assemble block 2 (shown as line number X).
The #ifndef directive inverts the condition, so block 2 (line number 12) will be assembled.
#define VERSION
_TEXT section CODE, PUBLIC,1
#ifdef VERSION
mov 0x01, D0
#else
mov 0x02, D0
#endif
#ifndef VERSION
mov 0x03, D1
#else
mov 0x04, D1
#endif
ifdef.lst Page 1
*** PanaX Series MN1030 Cross Assembler **
Loc Object Line Source
1 #define VERSION
2
3 _TEXT section CODE, PUBLIC, 1
4 #ifdef VERSION
00000000 8001 5 mov 0x01, D0
6 #else
7x mov 0x02, D0
8 #endif
9 #ifndef VERSION
10X mov 0x03, D1
11 #else
00000002 8504 12 mov 0x04, D1
13 #endif