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874c751cc5
Also add warning comment about threading implementations without matching atomics implementation to the atomics fallback implementation.
128 lines
2.8 KiB
C
128 lines
2.8 KiB
C
/*
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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 Libav.
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*
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* Libav 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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* Libav 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 Libav; 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 (*ptr == 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 <assert.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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assert(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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assert(res == 3);
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return 0;
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}
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#endif
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