Keil Software — A51/AX51/A251 Macro Assembler and Utilities |
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LIT (AX51 & A251 only)
The LIT directive provides a simple text substitution facility. The LIT directive has the following format:
symbol |
LIT |
'literal string' |
symbol |
LIT |
"literal string" |
where |
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symbol |
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is the name of the symbol to define. The literal string |
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specified in the LIT directive will be substituted for each |
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occurrence of symbol that is used in your assembly |
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program. |
literal string |
is a numeric expression which contains no forward |
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references, or a simple relocatable expression. |
Every time the symbol is encountered, it is replaced by the literal string |
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assigned to the symbol name. The symbol name follows the same rules as other |
identifiers, that is, a literal name is not encountered if it does not form a separate token. If a substring is to be replaced, symbol must be enclosed in braces: TEXT{symbol}. The assembler listing shows the expanded lines where literals are substituted.
Example
Source text containing literals before assembly:
$INCLUDE (REG51.INC)
REG1 |
LIT |
'R1' |
NUM |
LIT |
'A1' |
DBYTE |
LIT |
"DATA BYTE" |
FLAG |
LIT |
'ACC.3' |
?PR?MOD SEGMENT |
CODE |
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RSEG |
?PR?MOD |
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MOV |
REG1,#5 |
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SETB |
FLAG |
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JB |
FLAG,LAB_{NUM} |
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PUSH |
DBYTE 0 |
LAB_{NUM}: |
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END
Shaded directives and options are available only in AX51 and A251.
118 Chapter 4. Assembler Directives
Assembler listing from previous example:
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1 |
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$INCLUDE (REG51.INC) |
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+1 |
80 |
+1 |
$RESTORE |
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81 |
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82 |
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REG1 |
LIT |
'R1' |
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83 |
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NUM |
LIT |
'A1' |
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84 |
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DBYTE |
LIT |
"DATA BYTE" |
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85 |
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FLAG |
LIT |
'ACC.3' |
------ |
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86 |
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87 |
?PR?MOD SEGMENT CODE |
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------ |
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88 |
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RSEG ?PR?MOD |
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89 |
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000000 |
7E1005 |
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90 |
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MOV |
R1,#5 |
000003 |
D2E3 |
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91 |
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SETB |
ACC.3 |
000005 |
20E300 |
F |
92 |
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JB |
ACC.3,LAB_A1 |
000008 |
C000 |
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93 |
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PUSH |
DATA BYTE 0 |
00000A |
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94 |
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LAB_A1: |
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95 |
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96 |
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END |
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4
Shaded directives and options are available only in AX51 and A251.