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Re: c inline assembly
- From: Gedare Bloom <gedare at rtems dot org>
- To: ratheesh kannoth <ratheesh dot ksz at gmail dot com>
- Cc: linux-c-programming at vger dot kernel dot org, gcc-help at gcc dot gnu dot org
- Date: Sun, 19 Feb 2012 11:46:46 -0500
- Subject: Re: c inline assembly
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On Sat, Feb 18, 2012 at 1:01 AM, ratheesh kannoth
<ratheesh.ksz@gmail.com> wrote:
> I am using gcc on a 32bit? intel machine.? i have defined an inline function.
>
>
> This function is inline .? what all registers needs to pushed and
> poped in the inline assembly so that the functions wont
> disturb the registers in? the function ( in which it is C inlined? ).
>
Use the clobber list:
http://ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html#ss5.3
>
> inline unsigned long hello(unsigned long a)
>
> {
> ?int b;
> ?asm ("movl %1, %%eax;
> ? ? ?" movl %1, %%ebx;
> ? ? ? "movl ?%1, %%ecx;
> ? ? ? "movl ?%1, %%esi;
> ? ? ? "movl ?%1, %%edi;
>
> ? ? ? "movl %%eax, %0;"
> ? ? ? :"=r"(b) ? ? ? ?/* output */
> ? ? ? :"r"(a) ? ? ? ? /* input */
: "eax","ecx","esi","edi" /* clobber */
> ?);
> }
> --
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