The assembler syntax closely follows the HPPA instruction set reference manual; assembler directives and general syntax closely follow the HPPA assembly language reference manual, with a few noteworthy differences.
First, a colon may immediately follow a label definition. This is simply for compatibility with how most assembly language programmers write code.
Some obscure expression parsing problems may affect hand written code which
uses the spop instructions, or code which makes significant
use of the ! line separator.
as is much less forgiving about missing arguments and other
similar oversights than the HP assembler. as notifies you
of missing arguments as syntax errors; this is regarded as a feature, not a
bug.
Finally, as allows you to use an external symbol without
explicitly importing the symbol. Warning: in the future this will be
an error for HPPA targets.
Special characters for HPPA targets include:
‘;’ is the line comment character.
‘!’ can be used instead of a newline to separate statements.
Since ‘$’ has no special meaning, you may use it in symbol names.