|
| 1 | +// Copyright (c) 2003, Google Inc. |
| 2 | +// All rights reserved. |
| 3 | +// |
| 4 | +// Redistribution and use in source and binary forms, with or without |
| 5 | +// modification, are permitted provided that the following conditions are |
| 6 | +// met: |
| 7 | +// |
| 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 |
| 11 | +// copyright notice, this list of conditions and the following disclaimer |
| 12 | +// in the documentation and/or other materials provided with the |
| 13 | +// distribution. |
| 14 | +// * Neither the name of Google Inc. nor the names of its |
| 15 | +// contributors may be used to endorse or promote products derived from |
| 16 | +// this software without specific prior written permission. |
| 17 | +// |
| 18 | +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 19 | +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 20 | +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 21 | +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 22 | +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 23 | +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 24 | +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 25 | +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 26 | +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 27 | +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 28 | +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 29 | +// --- |
| 30 | +// |
| 31 | +// Author: Lei Zhang, Sasha Levitskiy |
| 32 | +// |
| 33 | +// This file is an internal atomic implementation, use base/atomicops.h instead. |
| 34 | +// |
| 35 | +// LinuxKernelCmpxchg and Barrier_AtomicIncrement are from Google Gears. |
| 36 | + |
| 37 | +#ifndef BASE_ATOMICOPS_INTERNALS_ARM_GENERIC_H_ |
| 38 | +#define BASE_ATOMICOPS_INTERNALS_ARM_GENERIC_H_ |
| 39 | + |
| 40 | +#include <stdio.h> |
| 41 | +#include <stdlib.h> |
| 42 | +#include "base/basictypes.h" |
| 43 | + |
| 44 | +typedef int32_t Atomic32; |
| 45 | + |
| 46 | +namespace base { |
| 47 | +namespace subtle { |
| 48 | + |
| 49 | +typedef int64_t Atomic64; |
| 50 | + |
| 51 | +// 0xffff0fc0 is the hard coded address of a function provided by |
| 52 | +// the kernel which implements an atomic compare-exchange. On older |
| 53 | +// ARM architecture revisions (pre-v6) this may be implemented using |
| 54 | +// a syscall. This address is stable, and in active use (hard coded) |
| 55 | +// by at least glibc-2.7 and the Android C library. |
| 56 | +// pLinuxKernelCmpxchg has both acquire and release barrier sematincs. |
| 57 | +typedef Atomic32 (*LinuxKernelCmpxchgFunc)(Atomic32 old_value, |
| 58 | + Atomic32 new_value, |
| 59 | + volatile Atomic32* ptr); |
| 60 | +LinuxKernelCmpxchgFunc pLinuxKernelCmpxchg ATTRIBUTE_WEAK = |
| 61 | + (LinuxKernelCmpxchgFunc) 0xffff0fc0; |
| 62 | + |
| 63 | +typedef void (*LinuxKernelMemoryBarrierFunc)(void); |
| 64 | +LinuxKernelMemoryBarrierFunc pLinuxKernelMemoryBarrier ATTRIBUTE_WEAK = |
| 65 | + (LinuxKernelMemoryBarrierFunc) 0xffff0fa0; |
| 66 | + |
| 67 | + |
| 68 | +inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr, |
| 69 | + Atomic32 old_value, |
| 70 | + Atomic32 new_value) { |
| 71 | + Atomic32 prev_value = *ptr; |
| 72 | + do { |
| 73 | + if (!pLinuxKernelCmpxchg(old_value, new_value, |
| 74 | + const_cast<Atomic32*>(ptr))) { |
| 75 | + return old_value; |
| 76 | + } |
| 77 | + prev_value = *ptr; |
| 78 | + } while (prev_value == old_value); |
| 79 | + return prev_value; |
| 80 | +} |
| 81 | + |
| 82 | +inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, |
| 83 | + Atomic32 new_value) { |
| 84 | + Atomic32 old_value; |
| 85 | + do { |
| 86 | + old_value = *ptr; |
| 87 | + } while (pLinuxKernelCmpxchg(old_value, new_value, |
| 88 | + const_cast<Atomic32*>(ptr))); |
| 89 | + return old_value; |
| 90 | +} |
| 91 | + |
| 92 | +inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr, |
| 93 | + Atomic32 increment) { |
| 94 | + for (;;) { |
| 95 | + // Atomic exchange the old value with an incremented one. |
| 96 | + Atomic32 old_value = *ptr; |
| 97 | + Atomic32 new_value = old_value + increment; |
| 98 | + if (pLinuxKernelCmpxchg(old_value, new_value, |
| 99 | + const_cast<Atomic32*>(ptr)) == 0) { |
| 100 | + // The exchange took place as expected. |
| 101 | + return new_value; |
| 102 | + } |
| 103 | + // Otherwise, *ptr changed mid-loop and we need to retry. |
| 104 | + } |
| 105 | +} |
| 106 | + |
| 107 | +inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, |
| 108 | + Atomic32 increment) { |
| 109 | + return Barrier_AtomicIncrement(ptr, increment); |
| 110 | +} |
| 111 | + |
| 112 | +inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr, |
| 113 | + Atomic32 old_value, |
| 114 | + Atomic32 new_value) { |
| 115 | + return NoBarrier_CompareAndSwap(ptr, old_value, new_value); |
| 116 | +} |
| 117 | + |
| 118 | +inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr, |
| 119 | + Atomic32 old_value, |
| 120 | + Atomic32 new_value) { |
| 121 | + return NoBarrier_CompareAndSwap(ptr, old_value, new_value); |
| 122 | +} |
| 123 | + |
| 124 | +inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) { |
| 125 | + *ptr = value; |
| 126 | +} |
| 127 | + |
| 128 | +inline void MemoryBarrier() { |
| 129 | + pLinuxKernelMemoryBarrier(); |
| 130 | +} |
| 131 | + |
| 132 | +inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) { |
| 133 | + *ptr = value; |
| 134 | + MemoryBarrier(); |
| 135 | +} |
| 136 | + |
| 137 | +inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) { |
| 138 | + MemoryBarrier(); |
| 139 | + *ptr = value; |
| 140 | +} |
| 141 | + |
| 142 | +inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) { |
| 143 | + return *ptr; |
| 144 | +} |
| 145 | + |
| 146 | +inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) { |
| 147 | + Atomic32 value = *ptr; |
| 148 | + MemoryBarrier(); |
| 149 | + return value; |
| 150 | +} |
| 151 | + |
| 152 | +inline Atomic32 Release_Load(volatile const Atomic32* ptr) { |
| 153 | + MemoryBarrier(); |
| 154 | + return *ptr; |
| 155 | +} |
| 156 | + |
| 157 | + |
| 158 | +// 64-bit versions are not implemented yet. |
| 159 | + |
| 160 | +inline void NotImplementedFatalError(const char *function_name) { |
| 161 | + fprintf(stderr, "64-bit %s() not implemented on this platform\n", |
| 162 | + function_name); |
| 163 | + abort(); |
| 164 | +} |
| 165 | + |
| 166 | +inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr, |
| 167 | + Atomic64 old_value, |
| 168 | + Atomic64 new_value) { |
| 169 | + NotImplementedFatalError("NoBarrier_CompareAndSwap"); |
| 170 | + return 0; |
| 171 | +} |
| 172 | + |
| 173 | +inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr, |
| 174 | + Atomic64 new_value) { |
| 175 | + NotImplementedFatalError("NoBarrier_AtomicExchange"); |
| 176 | + return 0; |
| 177 | +} |
| 178 | + |
| 179 | +inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr, |
| 180 | + Atomic64 increment) { |
| 181 | + NotImplementedFatalError("NoBarrier_AtomicIncrement"); |
| 182 | + return 0; |
| 183 | +} |
| 184 | + |
| 185 | +inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr, |
| 186 | + Atomic64 increment) { |
| 187 | + NotImplementedFatalError("Barrier_AtomicIncrement"); |
| 188 | + return 0; |
| 189 | +} |
| 190 | + |
| 191 | +inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) { |
| 192 | + NotImplementedFatalError("NoBarrier_Store"); |
| 193 | +} |
| 194 | + |
| 195 | +inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) { |
| 196 | + NotImplementedFatalError("Acquire_Store64"); |
| 197 | +} |
| 198 | + |
| 199 | +inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) { |
| 200 | + NotImplementedFatalError("Release_Store"); |
| 201 | +} |
| 202 | + |
| 203 | +inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) { |
| 204 | + NotImplementedFatalError("NoBarrier_Load"); |
| 205 | + return 0; |
| 206 | +} |
| 207 | + |
| 208 | +inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) { |
| 209 | + NotImplementedFatalError("Atomic64 Acquire_Load"); |
| 210 | + return 0; |
| 211 | +} |
| 212 | + |
| 213 | +inline Atomic64 Release_Load(volatile const Atomic64* ptr) { |
| 214 | + NotImplementedFatalError("Atomic64 Release_Load"); |
| 215 | + return 0; |
| 216 | +} |
| 217 | + |
| 218 | +inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr, |
| 219 | + Atomic64 old_value, |
| 220 | + Atomic64 new_value) { |
| 221 | + NotImplementedFatalError("Atomic64 Acquire_CompareAndSwap"); |
| 222 | + return 0; |
| 223 | +} |
| 224 | + |
| 225 | +inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr, |
| 226 | + Atomic64 old_value, |
| 227 | + Atomic64 new_value) { |
| 228 | + NotImplementedFatalError("Atomic64 Release_CompareAndSwap"); |
| 229 | + return 0; |
| 230 | +} |
| 231 | + |
| 232 | +} // namespace base::subtle |
| 233 | +} // namespace base |
| 234 | + |
| 235 | +#endif // BASE_ATOMICOPS_INTERNALS_ARM_GENERIC_H_ |
0 commit comments