From:	"Campbell, Rolf [SKY:1U32:EXCH]" <cp1v45 AT americasm01 DOT nt DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Why dosn't my asm getpixel() work?
Date:	Tue, 22 Jun 1999 09:38:09 -0400
Organization:	Nortel Networks
Lines:	27
Message-ID:	<376F91C1.1C5CB462@americasm01.nt.com>
References:	<3766f436 DOT 5083819 AT nntpserver DOT swip DOT net> <3768394B DOT 4C9E319E AT cartsys DOT com> <376981c9 DOT 8709864 AT nntpserver DOT swip DOT net>
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To:	djgpp AT delorie DOT com
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Gathers wrote:

> >6. The multiply can be optimized better; this is left as an exercise for
> >the reader.
> >
> mov ax,y
> mov bx,ax
> shl ax,8
> shl bx,6
> add ax,bx
> ax==y*320?

    On pre-Pentium machines it is 1 cycle faster to use, on post-486
machines it is 1 cycle slower to use:
mov bh, bl
xor bl, bl

instead of
shl bx, 6

PS:  This is not AT&T style assembler, so it won't work with DJGPP.

--
     -Rolf Campbell (39)3-6318

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