ARM VERSION 1.2 Using macros, Test-and-branch macro example, This macro can be invoked as follows

Writing ARM and Thumb Assembly Language

2.9Using macros

A macro definition is a block of code enclosed between MACRO and MEND directives. It defines a name that can be used instead of repeating the whole block of code. This has two main uses:

•to make it easier to follow the logic of the source code, by replacing a block of code with a single, meaningful name

•to avoid repeating a block of code several times.

Refer to MACRO and MEND on page 7-27 for more details.

2.9.1Test-and-branch macro example

Atest-and-branch operation requires two ARM instructions to implement. You can define a macro definition such as this:

MACRO

$label TestAndBranch $dest, $reg, $cc

$label CMP	$reg, #0
B$cc	$dest
MEND

The line after the MACRO directive is the macro prototype statement. The macro prototype statement defines the name (TestAndBranch) you use to invoke the macro. It also defines parameters ($label, $dest, $reg, and $cc). You must give values to the parameters when you invoke the macro. The assembler substitutes the values you give into the code.

This macro can be invoked as follows:

test	TestAndBranch	NonZero, r0, NE
	...
	...
NonZero

After substitution this becomes:

test	CMP	r0, #0
	BNE	NonZero
	...
	...
NonZero

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