Test-and-branch macro
example
In ARM code in any processor and in Thumb code in processors
before ARMv6T2, a test-and-branch operation requires two instructions
to implement.
You can define a macro definition such as this:
MACRO
$label TestAndBranch $dest, $reg, $cc
$label CMP $reg, #0
B$cc $dest
MEND
The line after the MACRO directive is the macro
prototype statement. This defines the name (TestAndBranch)
you use to invoke the macro. It also defines parameters ($label, $dest, $reg, and $cc).
Unspecified parameters are substituted with an empty string. For
this macro you must give values for $dest, $reg and $cc to
avoid syntax errors. 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
See also