| Ethan Yonker | 726a020 | 2014-12-16 20:01:38 -0600 | [diff] [blame^] | 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 _TW_SYS_ATOMICS_H |
| 29 | #define _TW_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 | |
| 48 | /* This was kanged from Android 4.4 bionic/libc/include/sys/atomics.h |
| 49 | * This header was removed in Android 5.0 in favor of stdatomics.h but |
| 50 | * to maintain compatibility across multiple trees, we are including our |
| 51 | * own copy. |
| 52 | */ |
| 53 | |
| 54 | #ifndef __ATOMIC_INLINE__ |
| 55 | #define __ATOMIC_INLINE__ static __inline__ __attribute__((always_inline)) |
| 56 | #endif |
| 57 | |
| 58 | __ATOMIC_INLINE__ int |
| 59 | __tw_atomic_cmpxchg(int old_value, int new_value, volatile int* ptr) |
| 60 | { |
| 61 | /* We must return 0 on success */ |
| 62 | return __sync_val_compare_and_swap(ptr, old_value, new_value) != old_value; |
| 63 | } |
| 64 | |
| 65 | __END_DECLS |
| 66 | |
| 67 | #endif /* _TW_SYS_ATOMICS_H */ |