1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2012 Google Inc. All rights reserved. 3 // http://code.google.com/p/protobuf/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are 7 // met: 8 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 17 // this software without specific prior written permission. 18 // 19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 // This file is an internal atomic implementation, use atomicops.h instead. 32 33 #ifndef GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_MIPS_GCC_H_ 34 #define GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_MIPS_GCC_H_ 35 36 #define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory") 37 38 namespace google { 39 namespace protobuf { 40 namespace internal { 41 42 // Atomically execute: 43 // result = *ptr; 44 // if (*ptr == old_value) 45 // *ptr = new_value; 46 // return result; 47 // 48 // I.e., replace "*ptr" with "new_value" if "*ptr" used to be "old_value". 49 // Always return the old value of "*ptr" 50 // 51 // This routine implies no memory barriers. 52 inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr, 53 Atomic32 old_value, 54 Atomic32 new_value) { 55 Atomic32 prev, tmp; 56 __asm__ __volatile__(".set push\n" 57 ".set noreorder\n" 58 "1:\n" 59 "ll %0, %5\n" // prev = *ptr 60 "bne %0, %3, 2f\n" // if (prev != old_value) goto 2 61 "move %2, %4\n" // tmp = new_value 62 "sc %2, %1\n" // *ptr = tmp (with atomic check) 63 "beqz %2, 1b\n" // start again on atomic error 64 "nop\n" // delay slot nop 65 "2:\n" 66 ".set pop\n" 67 : "=&r" (prev), "=m" (*ptr), "=&r" (tmp) 68 : "Ir" (old_value), "r" (new_value), "m" (*ptr) 69 : "memory"); 70 return prev; 71 } 72 73 // Atomically store new_value into *ptr, returning the previous value held in 74 // *ptr. This routine implies no memory barriers. 75 inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, 76 Atomic32 new_value) { 77 Atomic32 temp, old; 78 __asm__ __volatile__(".set push\n" 79 ".set noreorder\n" 80 "1:\n" 81 "ll %1, %2\n" // old = *ptr 82 "move %0, %3\n" // temp = new_value 83 "sc %0, %2\n" // *ptr = temp (with atomic check) 84 "beqz %0, 1b\n" // start again on atomic error 85 "nop\n" // delay slot nop 86 ".set pop\n" 87 : "=&r" (temp), "=&r" (old), "=m" (*ptr) 88 : "r" (new_value), "m" (*ptr) 89 : "memory"); 90 91 return old; 92 } 93 94 // Atomically increment *ptr by "increment". Returns the new value of 95 // *ptr with the increment applied. This routine implies no memory barriers. 96 inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, 97 Atomic32 increment) { 98 Atomic32 temp, temp2; 99 100 __asm__ __volatile__(".set push\n" 101 ".set noreorder\n" 102 "1:\n" 103 "ll %0, %2\n" // temp = *ptr 104 "addu %1, %0, %3\n" // temp2 = temp + increment 105 "sc %1, %2\n" // *ptr = temp2 (with atomic check) 106 "beqz %1, 1b\n" // start again on atomic error 107 "addu %1, %0, %3\n" // temp2 = temp + increment 108 ".set pop\n" 109 : "=&r" (temp), "=&r" (temp2), "=m" (*ptr) 110 : "Ir" (increment), "m" (*ptr) 111 : "memory"); 112 // temp2 now holds the final value. 113 return temp2; 114 } 115 116 inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr, 117 Atomic32 increment) { 118 ATOMICOPS_COMPILER_BARRIER(); 119 Atomic32 res = NoBarrier_AtomicIncrement(ptr, increment); 120 ATOMICOPS_COMPILER_BARRIER(); 121 return res; 122 } 123 124 // "Acquire" operations 125 // ensure that no later memory access can be reordered ahead of the operation. 126 // "Release" operations ensure that no previous memory access can be reordered 127 // after the operation. "Barrier" operations have both "Acquire" and "Release" 128 // semantics. A MemoryBarrier() has "Barrier" semantics, but does no memory 129 // access. 130 inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr, 131 Atomic32 old_value, 132 Atomic32 new_value) { 133 ATOMICOPS_COMPILER_BARRIER(); 134 Atomic32 res = NoBarrier_CompareAndSwap(ptr, old_value, new_value); 135 ATOMICOPS_COMPILER_BARRIER(); 136 return res; 137 } 138 139 inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr, 140 Atomic32 old_value, 141 Atomic32 new_value) { 142 ATOMICOPS_COMPILER_BARRIER(); 143 Atomic32 res = NoBarrier_CompareAndSwap(ptr, old_value, new_value); 144 ATOMICOPS_COMPILER_BARRIER(); 145 return res; 146 } 147 148 inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) { 149 *ptr = value; 150 } 151 152 inline void MemoryBarrier() { 153 __asm__ __volatile__("sync" : : : "memory"); 154 } 155 156 inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) { 157 *ptr = value; 158 MemoryBarrier(); 159 } 160 161 inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) { 162 MemoryBarrier(); 163 *ptr = value; 164 } 165 166 inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) { 167 return *ptr; 168 } 169 170 inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) { 171 Atomic32 value = *ptr; 172 MemoryBarrier(); 173 return value; 174 } 175 176 inline Atomic32 Release_Load(volatile const Atomic32* ptr) { 177 MemoryBarrier(); 178 return *ptr; 179 } 180 181 } // namespace internal 182 } // namespace protobuf 183 } // namespace google 184 185 #undef ATOMICOPS_COMPILER_BARRIER 186 187 #endif // GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_MIPS_GCC_H_ 188