Xref:	news2.mv.net comp.os.msdos.djgpp:3494
From:	beppu AT arcturus DOT oac DOT uci DOT edu (John Beppu)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Simple ASM question (direction flag)
Date:	6 May 1996 08:22:48 GMT
Organization:	University of California, Irvine
Lines:	35
Message-ID:	<4mkcso$h1l@news.service.uci.edu>
References:	<Pine DOT VUL DOT 3 DOT 91 DOT 960502095335 DOT 386D-100000 AT zeus DOT adv-boeblingen DOT de> <4ma8k3$spj AT freenet-news DOT carleton DOT ca>
NNTP-Posting-Host:	arcturus.oac.uci.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

>Lennart Steinke (steinke AT zeus DOT adv-boeblingen DOT de) writes:
>> Hi!
>> 
>> 	I need something like memcpy(),
>> but with inverted direction flag. So that
>> the dest. pointer points to the end of the used
>> memory, not to the beginning. I need the
>> same for memset(), too.
>> 
>> 	This can't be that hard, but
>> a) I'm not fluid in ASM, especially not with DJGPP,
>> b) have no ASM books here at work, and
>> c) have only the bins of DJGPP v2, so I can't look
>>    into the source of the above mentioned funcs.
>> 
>> I need these funcs to blit an bitmap mirrored to the
>> screen.



   If you were wondering about how to set the direction flag,
   it should be: 

	std

   Just to be safe, I'd clear the direction flag after doing the
   backward string instructions just in case.  The instruction
   to clear the direction flag is

	cld



--
   beppu AT ea DOT oac DOT uci DOT edu

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