## .macro

The commands .macro and .endm allow you to define macros that generate assembly output. For example, this definition specifies a macro sum that puts a sequence of numbers into memory:

        .macro  sum from=0, to=5
.long   \from
.if     \to-\from
sum     "(\from+1)",\to
.endif
.endm


With that definition, SUM 0,5' is equivalent to this assembly input:

        .long   0
.long   1
.long   2
.long   3
.long   4
.long   5

.macro macname
.macro macname macargs ...
Begin the definition of a macro called macname. If your macro definition requires arguments, specify their names after the macro name, separated by commas or spaces. You can supply a default value for any macro argument by following the name with =deflt'. For example, these are all valid .macro statements:
.macro comm
Begin the definition of a macro called comm, which takes no arguments.
.macro plus1 p, p1
.macro plus1 p p1
Either statement begins the definition of a macro called plus1, which takes two arguments; within the macro definition, write \p' or \p1' to evaluate the arguments.
.macro reserve_str p1=0 p2
Begin the definition of a macro called reserve_str, with two arguments. The first argument has a default value, but not the second. After the definition is complete, you can call the macro either as reserve_str a,b' (with \p1' evaluating to a and \p2' evaluating to b), or as reserve_str ,b' (with \p1' evaluating as the default, in this case 0', and \p2' evaluating to b).
When you call a macro, you can specify the argument values either by position, or by keyword. For example, sum 9,17' is equivalent to sum to=17, from=9'.
.endm
Mark the end of a macro definition.
.exitm
Exit early from the current macro definition.
\@
as maintains a counter of how many macros it has executed in this pseudo-variable; you can copy that number to your output with \@', but only within a macro definition.