FFmpeg/libavutil/atomic_gcc.h
James Almer faa9d29829 lavu/atomic: add support for the new memory model aware gcc built-ins
__sync built-ins are considered legacy and will be deprecated.
These new memory model aware built-ins have been available since GCC 4.7.0

Use them by default when available except for __atomic_compare_exchange_n(),
which is slower, and is instead implemented as a fallback for when and if gcc
removes the legacy __sync built-ins.

Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: James Almer <jamrial@gmail.com>
2014-10-29 14:09:58 -03:00

79 lines
2.3 KiB
C

/*
* Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
*
* 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_ATOMIC_GCC_H
#define AVUTIL_ATOMIC_GCC_H
#include <stdint.h>
#include "atomic.h"
#define avpriv_atomic_int_get atomic_int_get_gcc
static inline int atomic_int_get_gcc(volatile int *ptr)
{
#if HAVE_ATOMIC_COMPARE_EXCHANGE
return __atomic_load_n(ptr, __ATOMIC_SEQ_CST);
#else
__sync_synchronize();
return *ptr;
#endif
}
#define avpriv_atomic_int_set atomic_int_set_gcc
static inline void atomic_int_set_gcc(volatile int *ptr, int val)
{
#if HAVE_ATOMIC_COMPARE_EXCHANGE
__atomic_store_n(ptr, val, __ATOMIC_SEQ_CST);
#else
*ptr = val;
__sync_synchronize();
#endif
}
#define avpriv_atomic_int_add_and_fetch atomic_int_add_and_fetch_gcc
static inline int atomic_int_add_and_fetch_gcc(volatile int *ptr, int inc)
{
#if HAVE_ATOMIC_COMPARE_EXCHANGE
return __atomic_add_fetch(ptr, inc, __ATOMIC_SEQ_CST);
#else
return __sync_add_and_fetch(ptr, inc);
#endif
}
#define avpriv_atomic_ptr_cas atomic_ptr_cas_gcc
static inline void *atomic_ptr_cas_gcc(void * volatile *ptr,
void *oldval, void *newval)
{
#if HAVE_SYNC_VAL_COMPARE_AND_SWAP
#ifdef __ARMCC_VERSION
// armcc will throw an error if ptr is not an integer type
volatile uintptr_t *tmp = (volatile uintptr_t*)ptr;
return (void*)__sync_val_compare_and_swap(tmp, oldval, newval);
#else
return __sync_val_compare_and_swap(ptr, oldval, newval);
#endif
#else
__atomic_compare_exchange_n(ptr, &oldval, newval, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
return oldval;
#endif
}
#endif /* AVUTIL_ATOMIC_GCC_H */