FFmpeg/libavutil/atomic.h
Martin Storsjö e460aa3282 atomic: Check for __sync_val_compare_and_swap instead of __sync_synchronize
Not all gcc configurations have an implementation of all the atomic
operations, and some gcc configurations have some atomic builtins
implemented but not all.

Thus check for the most essential function, whose presence should
indicate that all others are present as well, since it can be used
to implement all the other ones.

Signed-off-by: Martin Storsjö <martin@martin.st>
2013-03-08 14:55:08 +02:00

75 lines
2.3 KiB
C

/*
* Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
*
* 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_ATOMIC_H
#define AVUTIL_ATOMIC_H
#include "config.h"
#if HAVE_MEMORYBARRIER
#include "atomic_win32.h"
#elif HAVE_SYNC_VAL_COMPARE_AND_SWAP
#include "atomic_gcc.h"
#elif HAVE_MACHINE_RW_BARRIER
#include "atomic_suncc.h"
#else
/**
* Load the current value stored in an atomic integer.
*
* @param ptr atomic integer
* @return the current value of the atomic integer
* @note This acts as a memory barrier.
*/
int avpriv_atomic_int_get(volatile int *ptr);
/**
* Store a new value in an atomic integer.
*
* @param ptr atomic integer
* @param val the value to store in the atomic integer
* @note This acts as a memory barrier.
*/
void avpriv_atomic_int_set(volatile int *ptr, int val);
/**
* Add a value to an atomic integer.
*
* @param ptr atomic integer
* @param inc the value to add to the atomic integer (may be negative)
* @return the new value of the atomic integer.
* @note This does NOT act as a memory barrier. This is primarily
* intended for reference counting.
*/
int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc);
/**
* Atomic pointer compare and swap.
*
* @param ptr pointer to the pointer to operate on
* @param oldval do the swap if the current value of *ptr equals to oldval
* @param newval value to replace *ptr with
* @return the value of *ptr before comparison
*/
void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval);
#endif /* HAVE_MEMORYBARRIER */
#endif /* AVUTIL_ATOMIC_H */