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FFmpeg/libavutil/arm/bswap.h
Mans Rullgard f64c2e710f bswap: make generic implementation more compiler-friendly
With these changes, gcc 4.5 and later recognise it as a bswap
and use the proper instructions on ARM and x86.  On x86, the
16-bit bswap is recognised from gcc 4.1.

Signed-off-by: Mans Rullgard <mans@mansr.com>
2011-12-12 12:14:14 +00:00

75 lines
1.9 KiB
C

/*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_ARM_BSWAP_H
#define AVUTIL_ARM_BSWAP_H
#include <stdint.h>
#include "config.h"
#include "libavutil/attributes.h"
#ifdef __ARMCC_VERSION
#if HAVE_ARMV6
#define av_bswap16 av_bswap16
static av_always_inline av_const unsigned av_bswap16(unsigned x)
{
__asm { rev16 x, x }
return x;
}
#define av_bswap32 av_bswap32
static av_always_inline av_const uint32_t av_bswap32(uint32_t x)
{
return __rev(x);
}
#endif /* HAVE_ARMV6 */
#elif HAVE_INLINE_ASM
#if HAVE_ARMV6
#define av_bswap16 av_bswap16
static av_always_inline av_const unsigned av_bswap16(unsigned x)
{
__asm__("rev16 %0, %0" : "+r"(x));
return x;
}
#endif
#if !AV_GCC_VERSION_AT_LEAST(4,5)
#define av_bswap32 av_bswap32
static av_always_inline av_const uint32_t av_bswap32(uint32_t x)
{
#if HAVE_ARMV6
__asm__("rev %0, %0" : "+r"(x));
#else
uint32_t t;
__asm__ ("eor %1, %0, %0, ror #16 \n\t"
"bic %1, %1, #0xFF0000 \n\t"
"mov %0, %0, ror #8 \n\t"
"eor %0, %0, %1, lsr #8 \n\t"
: "+r"(x), "=&r"(t));
#endif /* HAVE_ARMV6 */
return x;
}
#endif /* !AV_GCC_VERSION_AT_LEAST(4,5) */
#endif /* __ARMCC_VERSION */
#endif /* AVUTIL_ARM_BSWAP_H */