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libavutil
atomic.c
Go to the documentation of this file.
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/*
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* Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "
config.h
"
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#include "
atomic.h
"
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#if !HAVE_ATOMICS_NATIVE
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#if HAVE_PTHREADS
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#include <pthread.h>
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static
pthread_mutex_t
atomic_lock = PTHREAD_MUTEX_INITIALIZER;
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int
avpriv_atomic_int_get
(
volatile
int
*ptr)
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{
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int
res;
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pthread_mutex_lock
(&atomic_lock);
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res = *ptr;
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pthread_mutex_unlock
(&atomic_lock);
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return
res;
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}
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void
avpriv_atomic_int_set
(
volatile
int
*ptr,
int
val
)
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{
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pthread_mutex_lock
(&atomic_lock);
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*ptr =
val
;
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pthread_mutex_unlock
(&atomic_lock);
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}
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int
avpriv_atomic_int_add_and_fetch
(
volatile
int
*ptr,
int
inc)
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{
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int
res;
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pthread_mutex_lock
(&atomic_lock);
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*ptr += inc;
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res = *ptr;
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pthread_mutex_unlock
(&atomic_lock);
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return
res;
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}
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void
*
avpriv_atomic_ptr_cas
(
void
*
volatile
*ptr,
void
*oldval,
void
*newval)
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{
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void
*
ret
;
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pthread_mutex_lock
(&atomic_lock);
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ret = *ptr;
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if
(ret == oldval)
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*ptr = newval;
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pthread_mutex_unlock
(&atomic_lock);
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return
ret
;
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}
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#elif !HAVE_THREADS
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int
avpriv_atomic_int_get
(
volatile
int
*ptr)
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{
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return
*ptr;
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}
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void
avpriv_atomic_int_set
(
volatile
int
*ptr,
int
val
)
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{
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*ptr =
val
;
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}
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int
avpriv_atomic_int_add_and_fetch
(
volatile
int
*ptr,
int
inc)
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{
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*ptr += inc;
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return
*ptr;
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}
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void
*
avpriv_atomic_ptr_cas
(
void
*
volatile
*ptr,
void
*oldval,
void
*newval)
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{
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if
(*ptr == oldval) {
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*ptr = newval;
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return
oldval;
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}
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return
*ptr;
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}
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#else
/* HAVE_THREADS */
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/* This should never trigger, unless a new threading implementation
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* without correct atomics dependencies in configure or a corresponding
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* atomics implementation is added. */
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#error "Threading is enabled, but there is no implementation of atomic operations available"
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#endif
/* HAVE_PTHREADS */
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#endif
/* !HAVE_ATOMICS_NATIVE */
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#ifdef TEST
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#include "
avassert.h
"
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int
main
(
void
)
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{
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volatile
int
val
= 1;
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int
res;
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res =
avpriv_atomic_int_add_and_fetch
(&val, 1);
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av_assert0
(res == 2);
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avpriv_atomic_int_set
(&val, 3);
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res =
avpriv_atomic_int_get
(&val);
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av_assert0
(res == 3);
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return
0;
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}
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#endif
val
const char const char void * val
Definition:
avisynth_c.h:634
avpriv_atomic_int_get
int avpriv_atomic_int_get(volatile int *ptr)
Load the current value stored in an atomic integer.
Definition:
atomic.c:75
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition:
avassert.h:37
pthread_mutex_t
HMTX pthread_mutex_t
Definition:
os2threads.h:40
config.h
avpriv_atomic_int_set
void avpriv_atomic_int_set(volatile int *ptr, int val)
Store a new value in an atomic integer.
Definition:
atomic.c:80
avassert.h
simple assert() macros that are a bit more flexible than ISO C assert().
ret
ret
Definition:
avfilter.c:974
atomic.h
avpriv_atomic_int_add_and_fetch
int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc)
Add a value to an atomic integer.
Definition:
atomic.c:85
avpriv_atomic_ptr_cas
void * avpriv_atomic_ptr_cas(void *volatile *ptr, void *oldval, void *newval)
Atomic pointer compare and swap.
Definition:
atomic.c:91
pthread_mutex_unlock
static av_always_inline int pthread_mutex_unlock(pthread_mutex_t *mutex)
Definition:
os2threads.h:108
pthread_mutex_lock
static av_always_inline int pthread_mutex_lock(pthread_mutex_t *mutex)
Definition:
os2threads.h:101
main
int main(int argc, char **argv)
Definition:
main.c:22
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