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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/skia/include/core/SkThread.h"
#include <new>
#include "base/atomicops.h"
#include "base/basictypes.h"
#include "base/logging.h"
#include "base/synchronization/lock.h"
/** Adds one to the int specified by the address (in a thread-safe manner), and
returns the previous value.
No additional memory barrier is required.
This must act as a compiler barrier.
*/
int32_t sk_atomic_inc(int32_t* addr) {
// sk_atomic_inc is expected to return the old value,
// Barrier_AtomicIncrement returns the new value.
return base::subtle::NoBarrier_AtomicIncrement(addr, 1) - 1;
}
/* Subtracts one from the int specified by the address (in a thread-safe
manner), and returns the previous value.
Expected to act as a release (SL/S) memory barrier and a compiler barrier.
*/
int32_t sk_atomic_dec(int32_t* addr) {
// sk_atomic_dec is expected to return the old value,
// Barrier_AtomicIncrement returns the new value.
return base::subtle::Barrier_AtomicIncrement(addr, -1) + 1;
}
/** If sk_atomic_dec does not act as an aquire (L/SL) barrier, this is expected
to act as an aquire (L/SL) memory barrier and as a compiler barrier.
*/
void sk_membar_aquire__after_atomic_dec() { }
/** Adds one to the int specified by the address iff the int specified by the
address is not zero (in a thread-safe manner), and returns the previous
value.
No additional memory barrier is required.
This must act as a compiler barrier.
*/
int32_t sk_atomic_conditional_inc(int32_t* addr) {
int32_t value = *addr;
while (true) {
if (value == 0) {
return 0;
}
int32_t before;
before = base::subtle::Acquire_CompareAndSwap(addr, value, value + 1);
if (before == value) {
return value;
} else {
value = before;
}
}
}
/** If sk_atomic_conditional_inc does not act as an aquire (L/SL) barrier, this
is expected to act as an aquire (L/SL) memory barrier and as a compiler
barrier.
*/
void sk_membar_aquire__after_atomic_conditional_inc() { }
SkMutex::SkMutex() {
COMPILE_ASSERT(sizeof(base::Lock) <= sizeof(fStorage), Lock_is_too_big_for_SkMutex);
base::Lock* lock = reinterpret_cast<base::Lock*>(fStorage);
new(lock) base::Lock();
}
SkMutex::~SkMutex() {
base::Lock* lock = reinterpret_cast<base::Lock*>(fStorage);
lock->~Lock();
}
void SkMutex::acquire() {
base::Lock* lock = reinterpret_cast<base::Lock*>(fStorage);
lock->Acquire();
}
void SkMutex::release() {
base::Lock* lock = reinterpret_cast<base::Lock*>(fStorage);
lock->Release();
}
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