From:	"Edgar Allan Tu" <edgar AT key DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	gcc inline assembly syntax
Date:	28 Jan 1997 03:46:40 GMT
Organization:	Nanospace
Lines:	36
Message-ID:	<01bc0ccf$cef8b2a0$80c4c7cd@etu.planetweb>
NNTP-Posting-Host:	205.199.196.128
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hi masters of gnu syntax,

I'm new to doing inline assembly in gnu C.  I'm try to do a code like this:
#define FIXMUL(a,b)	(				\
{							\
	long _result;					\
	asm (						\
		"imull %%ebx\n\t"			\
		"shld $16,%%eax\n\t");			\
	__result;					\
}

I can't seem to figure out how to assign my params a to eax, b to ebx and
my return code in edx to __result.  The only way I was able to do this was
to do the following:
#define FIXMUL(a, b)	(				\
{							\
	long __result;					\
	asm (						\
		"movl %2,%%ebx\n\t"			\
		"movl %1,%%eax\n\t"			\
		"imull %%ebx\n\t"			\
		"shld $16,%%eax,%%edx\n\t"		\
		"movl %%edx,%0"			\
		: "=g" (__result)				\
		: "g" (a), "g" (b)				\
		: "%ebx","%eax","%edx");			\
	__result;					\
})

Is there an easier way to do this?  The second way adds a lot of
unnecessary code which defeats my purpose of writing this in assembly to
speed things up.  Anyone? Anyone?

Thanks in advance,
Edgar Tu

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