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From: ford@elgar.UUCP (Mike "Ford" Ditto)
Newsgroups: comp.sys.att,unix-pc.general
Subject: Re: /bin/as
Summary: REL-REL requires swbeg
Keywords: unixpc sgs assembler
Message-ID: <185@elgar.UUCP>
Date: 17 Jun 88 04:18:20 GMT
References: <1018@umbc3.UMD.EDU>
Reply-To: ford@kenobi.cts.com (Mike "Ford" Ditto)
Organization: Omnicron Data Systems,  Bonita, CA
Lines: 49

In article <1018@umbc3.UMD.EDU> alex@umbc3.UMD.EDU (Alex S. Crain) writes:
>
>	ARRRGGGGGG! Has anyone ever managed to get the %!*$# assembler to
>take rel-rel expressions? Ie: some thing like
>
>	mov.w	L2-L1(%pc,%d0.w),%d0

Although the manual does that they can be used ("with caution"),
trying to use them quickly shows that this is not true.  There is one
way to make them work (and even with no "caution" required): use the
swbeg statement.  This is an incredibly bogus "feature" of the
assembler, which is used like so:

L1:
	swbeg	&3	# the 3 is the number of rel-rel short's which follow
	short	L2-L1
	short	L3-L1
	short	L4-L1
L2:
	mov.l	&42,%d0
	bra	L5
L3:
	mov.l	&99,%d0
	bra	L5
L4:
	etc...

Obviously, this is only helpful if you want to store the rel-rel
expressions in a table.

That is what is output by the SGS C compiler, and the assembler takes
it just fine.  I couldn't make GNU CC output the swbeg statement, so
I just had it never generate switch tables until I figure out a way
around it.

>or
>
>	set arf,.+1    # or ~+1, or any other syntax that you like
>		^^^

~ is the proper symbol for location counter, and I have used it
successfully, although not in a "set" directive.


					-=] Ford [=-

"Once there were parking lots,		(In Real Life:  Mike Ditto)
now it's a peaceful oasis.		ford@kenobi.cts.com
This was a Pizza Hut,			...!sdcsvax!crash!kenobi!ford
now it's all covered with daisies." -- Talking Heads