An
asm macro
is the mechanism by which programs use the enhanced
asm facility.
asm macros have a
definition
and
uses.
The definition includes a set of pattern/body pairs.
Each pattern describes the storage modes
that the actual arguments must match for the
asm macro body to be expanded.
The uses resemble C function calls.
storage mode
The storage mode, or mode,
of an asm macro argument is the compiler's
idea of where the argument can be found at run time.
Examples are ``in a register'' or ``in memory''.
pattern
A pattern
specifies the modes for each of the arguments of an asm macro.
When the modes in the pattern
all match those of the use, the corresponding body is expanded.
asm macro body
The
asm macro body,
or
body,
is the portion of code that will be expanded by the compiler
when the corresponding pattern matches.
The body may contain references to the formal parameters, in
which case the compiler substitutes the corresponding assembly language code.