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Assembler User Guide
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Overview of the Assembler Overview of the ARM Architecture Structure of Assembly Language Modules Writing ARM Assembly Language Condition Codes Using the Assembler 
Symbols, Literals, Expressions, and Operators Symbol naming rules Variables Numeric constants Assembly time substitution of variables Register-relative and PC-relative expressions Labels Labels for PC-relative addresses Labels for register-relative addresses Labels for absolute addresses Local labels Syntax of local labels String expressions String literals Numeric expressions Numeric literals Floating-point literals Logical expressions Logical literals Unary operators Binary operators Multiplicative operators String manipulation operators Shift operators Addition, subtraction, and logical operators Relational operators Boolean operators Operator precedence Difference between operator precedence in armasm a VFP ProgrammingVariables
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| Home > Symbols, Literals, Expressions, and Operators > Variables | |||
The value of a variable can be changed as assembly proceeds. Variables are local to the assembler. This means that in the generated code or data, every instance of the variable has a fixed value.
Variables are of three types:
numeric
logical
string.
The type of a variable cannot be changed.
The range of possible values of a numeric variable is the same as the range of possible values of a numeric constant or numeric expression.
The possible values of a logical variable are {TRUE} or {FALSE}.
The range of possible values of a string variable is the same as the range of values of a string expression.
Use the GBLA, GBLL, GBLS, LCLA, LCLL, and LCLS directives to declare symbols representing variables, and assign values to them using the SETA, SETL, and SETS directives.
Examplea SETA 100; L1 MOV R1, #(a*5); In the object file, this is MOV R1, #500 a SETA 200; Value of ‘a’ is 200 only after this point. ; The previous instruction will always be MOV R1, #500 … BNE L1; When the processor branches to L1, it executes MOV R1, #500
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| Non-Confidential | ID061811 |
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