Xref:	news2.mv.net comp.os.msdos.djgpp:2091
From:	korpela AT islay DOT ssl DOT berkeley DOT edu (Eric J. Korpela)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Is this ASM ok?
Date:	22 Mar 1996 18:41:13 GMT
Organization:	Cal Berkeley-- Space Sciences Lab
Lines:	26
Message-ID:	<4ius89$76n@agate.berkeley.edu>
References:	<3150B8B2 DOT 8B2 AT jeffnet DOT org> <4ishog$obf AT mack DOT rt66 DOT com>
NNTP-Posting-Host:	islay.ssl.berkeley.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In article <4ishog$obf AT mack DOT rt66 DOT com>,
Brennan "Mr. Wacko" Underwood <brennan AT mack DOT rt66 DOT com> wrote:
>asm(
>  "loopf:\n\t"
>  "movb %%dh, (%%edi)\n\t"	/* write integer portion of color - U1 */
>  "addl %%ebx, %%edx\n\t"       /* Add colstep to col             - V1 */
>  "incl %%edi\n\t"		/* increment edi                  - U2 */
>  "decl %ecx\n\t"		/* decrement count                - V2 */
>  "jnz loopf"     	        /* If ecx not zero goto loop      - U3 */
>  : : "D" (tscreen), "d" (tcol1), "b" (tcolstep), "c" (tlength)/*loaded regs*/
>  : "%edi", "%ebx", "%ecx", "%edx"); /* clobbered regs */

I think there is a problem with your clobbered register list.  Because 
you have already specified the loaded registers gcc already knows that
these registers will be modified.  Ordinarily I wouldn't think that
would be a problem, but the GCC info pages state that "The input
operands are guaranteed not to use any of the clobbered registers."
There's clearly a contradiction here, and I would hope GCC flags
this as an error, or at least gives a warning.

Eric
-- 
Eric Korpela                        |  An object at rest can never be
korpela AT ssl DOT berkeley DOT edu            |  stopped.
<a href="http://www.cs.indiana.edu/finger/mofo.ssl.berkeley.edu/korpela/w">
Click here for more info.</a>

- Raw text -