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RealView Assembler User's Guide
Preface Introduction Writing ARM Assembly Language Assembler Reference Command syntax
Obtaining a list of available options Specifying command‑line options with an environm AAPCS Floating‑point model Memory access attributes Pre‑executing a SET directive Splitting long LDMs and STMs Listing output to a file Project template options Controlling the output of diagnostic messages Controlling exception table generation Format of source lines Predefined register and coprocessor names Predeclared register names Predeclared extension register names Predeclared coprocessor names Built‑in variables and constants Symbols Symbol naming rules Variables Numeric constants Assembly time substitution of variables Labels Local labels Expressions, literals, and operators String expressions String literals Numeric expressions Numeric literals Floating‑point literals Register‑relative and program‑relative express Logical expressions Logical literals Operator precedence Unary operators Binary operators Diagnostic messages Interlocks IT block generation Thumb branch target alignment Using the C preprocessor ARM and Thumb Instructions Directives ReferenceLocal labels
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| Home > Assembler Reference > Symbols > Local labels | |||
A local label is a number in the range 0‑99, optionally followed by a name. The same number can be used for more than one local label in an area.
A local label can be used in place of symbol
on its own, that is, where there is no instruction or directive
on a line that contains an instruction
on a line that contains a code‑ or data‑generating directive.
A local label is generally used where you might use a program‑relative label (see Labels).
Local labels are typically used for loops and conditional code within a routine, or for small subroutines that are only used locally. They are particularly useful in macros (see MACRO and MEND).
Use the ROUT directive to limit the scope of local labels (see ROUT). A reference to a local label refers to a matching label within the same scope. If there is no matching label within the scope in either direction, the assembler generates an error message and the assembly fails.
You can use the same number for more than one local label even within the same scope. By default, the assembler links a local label reference to:
the most recent local label of the same number, if there is one within the scope
the next following local label of the same number, if there is not a preceding one within the scope.
Use the optional parameters to modify this search pattern if required.
The syntax of a local label is:
n{routname}
The syntax of a reference to a local label is:
%{F|B}{A|T}n{routname}
where:
nis the number of the local label.
routnameis the name of the current scope.
%introduces the reference.
Finstructs the assembler to search forwards only.
Binstructs the assembler to search backwards only.
Ainstructs the assembler to search all macro levels.
Tinstructs the assembler to look at this macro level only.
If neither F nor B is specified, the assembler searches backwards first, then forwards.
If neither A nor T is specified, the assembler searches all macros from the current level to the top level, but does not search lower level macros.
If routnameROUT directive. If it does not match, the assembler generates an error message and the assembly fails.
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