From 65f1d45dcc71186ede72fff950996099d23359bd Mon Sep 17 00:00:00 2001 From: "Ronald S. Bultje" Date: Sun, 2 Dec 2012 14:34:50 -0800 Subject: lavu: add support for atomic operations. These could be used for reference counting, or for keeping track of decoding progress in references in multithreaded decoders. Support is provided by gcc/msvc/suncc intrinsics, with a fallback using pthread mutexes. Signed-off-by: Anton Khirnov --- libavutil/atomic.h | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 libavutil/atomic.h (limited to 'libavutil/atomic.h') diff --git a/libavutil/atomic.h b/libavutil/atomic.h new file mode 100644 index 0000000000..dad93bd1aa --- /dev/null +++ b/libavutil/atomic.h @@ -0,0 +1,74 @@ +/* + * Copyright (c) 2012 Ronald S. Bultje + * + * 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_SYNCHRONIZE +#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 */ -- cgit v1.2.3