1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28#ifndef _SYS_ATOMICS_H 29#define _SYS_ATOMICS_H 30 31#include <sys/cdefs.h> 32#include <sys/time.h> 33 34__BEGIN_DECLS 35 36/* Note: atomic operations that were exported by the C library didn't 37 * provide any memory barriers, which created potential issues on 38 * multi-core devices. We now define them as inlined calls to 39 * GCC sync builtins, which always provide a full barrier. 40 * 41 * NOTE: The C library still exports atomic functions by the same 42 * name to ensure ABI stability for existing NDK machine code. 43 * 44 * If you are an NDK developer, we encourage you to rebuild your 45 * unmodified sources against this header as soon as possible. 46 */ 47#define __ATOMIC_INLINE__ static __inline__ __attribute__((always_inline)) 48 49__ATOMIC_INLINE__ int 50__atomic_cmpxchg(int old_value, int new_value, volatile int* ptr) 51{ 52 /* We must return 0 on success */ 53 return __sync_val_compare_and_swap(ptr, old_value, new_value) != old_value; 54} 55 56__ATOMIC_INLINE__ int 57__atomic_swap(int new_value, volatile int *ptr) 58{ 59 int old_value; 60 do { 61 old_value = *ptr; 62 } while (__sync_val_compare_and_swap(ptr, old_value, new_value) != old_value); 63 return old_value; 64} 65 66__ATOMIC_INLINE__ int 67__atomic_dec(volatile int *ptr) 68{ 69 return __sync_fetch_and_sub (ptr, 1); 70} 71 72__ATOMIC_INLINE__ int 73__atomic_inc(volatile int *ptr) 74{ 75 return __sync_fetch_and_add (ptr, 1); 76} 77 78 79int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout); 80int __futex_wake(volatile void *ftx, int count); 81 82__END_DECLS 83 84#endif /* _SYS_ATOMICS_H */ 85