1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "atomic.h"
18#include "base/mutex.h"
19#include "base/stl_util.h"
20#include "thread-inl.h"
21
22namespace art {
23
24std::vector<Mutex*>* QuasiAtomic::gSwapMutexes = nullptr;
25
26Mutex* QuasiAtomic::GetSwapMutex(const volatile int64_t* addr) {
27  return (*gSwapMutexes)[(reinterpret_cast<uintptr_t>(addr) >> 3U) % kSwapMutexCount];
28}
29
30void QuasiAtomic::Startup() {
31  if (kNeedSwapMutexes) {
32    gSwapMutexes = new std::vector<Mutex*>;
33    for (size_t i = 0; i < kSwapMutexCount; ++i) {
34      gSwapMutexes->push_back(new Mutex("QuasiAtomic stripe", kSwapMutexesLock));
35    }
36  }
37}
38
39void QuasiAtomic::Shutdown() {
40  if (kNeedSwapMutexes) {
41    STLDeleteElements(gSwapMutexes);
42    delete gSwapMutexes;
43  }
44}
45
46int64_t QuasiAtomic::SwapMutexRead64(volatile const int64_t* addr) {
47  MutexLock mu(Thread::Current(), *GetSwapMutex(addr));
48  return *addr;
49}
50
51void QuasiAtomic::SwapMutexWrite64(volatile int64_t* addr, int64_t value) {
52  MutexLock mu(Thread::Current(), *GetSwapMutex(addr));
53  *addr = value;
54}
55
56
57bool QuasiAtomic::SwapMutexCas64(int64_t old_value, int64_t new_value, volatile int64_t* addr) {
58  MutexLock mu(Thread::Current(), *GetSwapMutex(addr));
59  if (*addr == old_value) {
60    *addr = new_value;
61    return true;
62  }
63  return false;
64}
65
66}  // namespace art
67