2 * Copyright (C) 2008 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 #ifndef _DALVIK_ATOMIC
20 #define _DALVIK_ATOMIC
22 #include <utils/Atomic.h> /* use common Android atomic ops */
25 * Memory barrier. Guarantee that register-resident variables
26 * are flushed to memory, and guarantee that instructions before
27 * the barrier do not get reordered to appear past it.
29 * 'asm volatile ("":::"memory")' is probably overkill, but it's correct.
30 * There may be a way to do it that doesn't flush every single register.
32 * TODO: look into the wmb() family on Linux and equivalents on other systems.
34 #define MEM_BARRIER() do { asm volatile ("":::"memory"); } while (0)
37 * Atomic compare-and-swap macro.
39 * If *_addr equals "_old", replace it with "_new" and return 1. Otherwise
40 * return 0. (e.g. x86 "cmpxchgl" instruction.)
42 * Underlying function is currently declared:
43 * int android_atomic_cmpxchg(int32_t old, int32_t new, volatile int32_t* addr)
45 #define ATOMIC_CMP_SWAP(_addr, _old, _new) \
46 (android_atomic_cmpxchg((_old), (_new), (_addr)) == 0)
48 #endif /*_DALVIK_ATOMIC*/