Date: Thu, 23 Dec 2004 12:23:02 -0800 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: Sean McNeil <sean@mcneil.com> Cc: amd64@freebsd.org Subject: Re: what is the proper asm spec for xchg Message-ID: <20041223202302.GG19624@funkthat.com> In-Reply-To: <1103830283.53421.3.camel@server.mcneil.com> References: <1103830283.53421.3.camel@server.mcneil.com>
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Sean McNeil wrote this message on Thu, Dec 23, 2004 at 11:31 -0800:
> I'm looking at why audio/sdl_mixer will not compile and I see that
> devel/sdl12 has an include with
>
> #elif defined(__GNUC__) && defined(__x86_64__)
> static __inline__ Uint16 SDL_Swap16(Uint16 x)
> {
> __asm__("xchgb %b0,%h0" : "=q" (x) : "0" (x));
> return x;
> }
>
> This appears to be incorrect as it is giving errors when compiled. Does
> anyone more conversant with asm directives for amd64 have an idea what
> this should be?
well, from amd64/include/endian.h:
#define __byte_swap_word_var(x) \
__extension__ ({ register __uint16_t __X = (x); \
__asm ("xchgb %h0, %b0" : "+Q" (__X)); \
__X; })
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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