`.irp SYMBOL,VALUES'...
=======================
Evaluate a sequence of statements assigning different values to
SYMBOL. The sequence of statements starts at the `.irp' directive, and
is terminated by an `.endr' directive. For each VALUE, SYMBOL is set
to VALUE, and the sequence of statements is assembled. If no VALUE is
listed, the sequence of statements is assembled once, with SYMBOL set
to the null string. To refer to SYMBOL within the sequence of
statements, use \SYMBOL.
For example, assembling
.irp param,1,2,3
move d\param,sp@-
.endr
is equivalent to assembling
move d1,sp@-
move d2,sp@-
move d3,sp@-