From f6c387128427e121477c1b32ad35cdcaa5101ba3 Mon Sep 17 00:00:00 2001 From: The Android Open Source Project Date: Tue, 3 Mar 2009 19:28:47 -0800 Subject: auto import from //depot/cupcake/@135843 --- vm/Atomic.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 vm/Atomic.h (limited to 'vm/Atomic.h') diff --git a/vm/Atomic.h b/vm/Atomic.h new file mode 100644 index 000000000..bc0203c10 --- /dev/null +++ b/vm/Atomic.h @@ -0,0 +1,48 @@ +/* + * Copyright (C) 2008 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +/* + * Atomic operations + */ +#ifndef _DALVIK_ATOMIC +#define _DALVIK_ATOMIC + +#include /* use common Android atomic ops */ + +/* + * Memory barrier. Guarantee that register-resident variables + * are flushed to memory, and guarantee that instructions before + * the barrier do not get reordered to appear past it. + * + * 'asm volatile ("":::"memory")' is probably overkill, but it's correct. + * There may be a way to do it that doesn't flush every single register. + * + * TODO: look into the wmb() family on Linux and equivalents on other systems. + */ +#define MEM_BARRIER() do { asm volatile ("":::"memory"); } while (0) + +/* + * Atomic compare-and-swap macro. + * + * If *_addr equals "_old", replace it with "_new" and return 1. Otherwise + * return 0. (e.g. x86 "cmpxchgl" instruction.) + * + * Underlying function is currently declared: + * int android_atomic_cmpxchg(int32_t old, int32_t new, volatile int32_t* addr) + */ +#define ATOMIC_CMP_SWAP(_addr, _old, _new) \ + (android_atomic_cmpxchg((_old), (_new), (_addr)) == 0) + +#endif /*_DALVIK_ATOMIC*/ -- cgit v1.2.3