dalvik/vm/Atomic.h

   1 /*
   2  * Copyright (C) 2008 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 /*
  18  * Atomic operations
  19  */
  20 #ifndef DALVIK_ATOMIC_H_
  21 #define DALVIK_ATOMIC_H_
  22
  23 #include <cutils/atomic.h>          /* use common Android atomic ops */
  24 #include <cutils/atomic-inline.h>   /* and some uncommon ones */
  25
  26 /*
  27  * NOTE: Two "quasiatomic" operations on the exact same memory address
  28  * are guaranteed to operate atomically with respect to each other,
  29  * but no guarantees are made about quasiatomic operations mixed with
  30  * non-quasiatomic operations on the same address, nor about
  31  * quasiatomic operations that are performed on partially-overlapping
  32  * memory.
  33  *
  34  * Only the "Sync" versions of these provide a memory barrier.
  35  */
  36
  37 /*
  38  * Swap the 64-bit value at "addr" with "value".  Returns the previous
  39  * value.
  40  */
  41 extern "C" int64_t dvmQuasiAtomicSwap64(int64_t value, volatile int64_t* addr);
  42
  43 /*
  44  * Swap the 64-bit value at "addr" with "value".  Returns the previous
  45  * value.  Provides memory barriers.
  46  */
  47 extern "C" int64_t dvmQuasiAtomicSwap64Sync(int64_t value,
  48                                             volatile int64_t* addr);
  49
  50 /*
  51  * Read the 64-bit value at "addr".
  52  */
  53 extern "C" int64_t dvmQuasiAtomicRead64(volatile const int64_t* addr);
  54
  55 /*
  56  * If the value at "addr" is equal to "oldvalue", replace it with "newvalue"
  57  * and return 0.  Otherwise, don't swap, and return nonzero.
  58  */
  59 int dvmQuasiAtomicCas64(int64_t oldvalue, int64_t newvalue,
  60         volatile int64_t* addr);
  61
  62 #endif  // DALVIK_ATOMIC_H_