On Wed, 13 Jul 2005 23:13:45 +0200, in comp.lang.asm370
(Message-ID:<[EMAIL PROTECTED]>)
"Michel Castelein"
<[EMAIL PROTECTED]> wrote:
So, I'm wondering why the expansion of the SAVE macro
begins with a DS 0H.
That's redundant, isn't it?
Most macros start with an optional label. Rather
than tying the label to the first generated machine
instruction, it's convenient to tie it to a DS 0H. That
allows you to easily add extra code at the beginning and to
have multiple expansions (depending on parms specified)
without having multiple label handling.
In open code, people often coded
LABEL EQU *
but, if there was an odd-length constant prior to it, it
would not be halfword aligned, so people started using the
DS 0H technique, instead. (Also, IIRC, the TEST
instruction has more information if you code as DS 0H.)
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