ARM VERSION 1.2 - page 309

Directives Reference

7.4.2 MACRO and MEND

The

MACRO

directive marks the start of the definition of a macro. Macro expansion

terminates at the

MEND

directive. See Using macros on page2-48 for further information.

Syntax

Two directives are used to define a macro. The syntax is:

MACRO

{$label} macroname {$parameter{,$parameter}...}

; code

MEND

where:

$label

is a parameter that is substituted with a symbol given when the

macro is invoked. The symbol is usually a label.

macroname

is the name of the macro. It must not begin with an instruction or

directive name.

$parameter

is a parameter t hat is substitut ed when the ma cro is invoked. A

default value for a parameter can be set using this format:

$parameter="default value"

Double quotes must be used if there are any spaces within, or at

either end of, the default value.

Usage

If you start any

WHILE...WEND

loops or

IF...ENDIF

conditions within a macro, they must

be closed before the

MEND

directive is reached. See MEXIT on page7-29 if you need to

allow an early exit from a macro, for example from within a loop.

Within the macro body, parameters such as

$label

$parameter

can be used in the same

way as other variables (see Assembly time substitution of variables on page 3-14). They

are given new values each time the macro is invoked. Parameters must begin with

distinguish them from ordinary symbols. Any number of parameters can be used.

$label

is optional. It is useful if the macro defines internal labels. It is treated as a

parameter to the macro. It does not necessarily represent the first instruction in the

macro expansion. The macro defines the locations of any labels.