FFmpeg/libavutil/emms.h

/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVUTIL_EMMS_H
#define AVUTIL_EMMS_H

#include "config.h"
#include "libavutil/attributes.h"

#if ARCH_X86

void avpriv_emms_asm(void);

#if HAVE_MMX_INLINE
#ifndef __MMX__
#include "libavutil/cpu.h"
#endif

#   define emms_c emms_c
/**
 * Empty mmx state.
 * this must be called between any dsp function and float/double code.
 * for example sin(); dsp->idct_put(); emms_c(); cos()
 * Note, *alloc() and *free() also use float code in some libc implementations
 * thus this also applies to them or any function using them.
 */
static av_always_inline void emms_c(void)
{
/* Some inlined functions may also use mmx instructions regardless of
 * runtime cpuflags. With that in mind, we unconditionally empty the
 * mmx state if the target cpu chosen at configure time supports it.
 */
#if !defined(__MMX__)
    if(av_get_cpu_flags() & AV_CPU_FLAG_MMX)
#endif
        __asm__ volatile ("emms" ::: "memory");
}
#elif HAVE_MMX && HAVE_MM_EMPTY
#   include <mmintrin.h>
#   define emms_c _mm_empty
#elif HAVE_MMX_EXTERNAL
#   define emms_c avpriv_emms_asm
#endif /* HAVE_MMX_INLINE */

#endif /* ARCH_X86 */

#ifndef emms_c
#   define emms_c() do {} while(0)
#endif

#endif /* AVUTIL_EMMS_H */