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authorSteve Kondik <shade@chemlab.org>2012-11-18 14:51:59 -0800
committerSteve Kondik <shade@chemlab.org>2012-11-18 14:51:59 -0800
commit4ec08dd85e9e4584f1bb0cd6110590f367d8b258 (patch)
treed76c7a2dc7d79fc7d52a93a907fd56c830d3cf84 /base/atomicops_internals_mips_gcc.h
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parentdb1b8993439cc1b0f741735e15d72a8cd67a6752 (diff)
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Merge branch 'jb-mr1-release' of https://android.googlesource.com/platform/external/chromium into mr1-staging
Diffstat (limited to 'base/atomicops_internals_mips_gcc.h')
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1 files changed, 162 insertions, 0 deletions
diff --git a/base/atomicops_internals_mips_gcc.h b/base/atomicops_internals_mips_gcc.h
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+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file is an internal atomic implementation, use base/atomicops.h instead.
+//
+// LinuxKernelCmpxchg and Barrier_AtomicIncrement are from Google Gears.
+
+#ifndef BASE_ATOMICOPS_INTERNALS_MIPS_GCC_H_
+#define BASE_ATOMICOPS_INTERNALS_MIPS_GCC_H_
+#pragma once
+
+#define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory")
+
+namespace base {
+namespace subtle {
+
+// Atomically execute:
+// result = *ptr;
+// if (*ptr == old_value)
+// *ptr = new_value;
+// return result;
+//
+// I.e., replace "*ptr" with "new_value" if "*ptr" used to be "old_value".
+// Always return the old value of "*ptr"
+//
+// This routine implies no memory barriers.
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ Atomic32 prev, tmp;
+ __asm__ __volatile__(".set push\n"
+ ".set noreorder\n"
+ "1:\n"
+ "ll %0, %5\n" // prev = *ptr
+ "bne %0, %3, 2f\n" // if (prev != old_value) goto 2
+ "move %2, %4\n" // tmp = new_value
+ "sc %2, %1\n" // *ptr = tmp (with atomic check)
+ "beqz %2, 1b\n" // start again on atomic error
+ "nop\n" // delay slot nop
+ "2:\n"
+ ".set pop\n"
+ : "=&r" (prev), "=m" (*ptr), "=&r" (tmp)
+ : "Ir" (old_value), "r" (new_value), "m" (*ptr)
+ : "memory");
+ return prev;
+}
+
+// Atomically store new_value into *ptr, returning the previous value held in
+// *ptr. This routine implies no memory barriers.
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+ Atomic32 new_value) {
+ Atomic32 temp, old;
+ __asm__ __volatile__(".set push\n"
+ ".set noreorder\n"
+ "1:\n"
+ "ll %1, %2\n" // old = *ptr
+ "move %0, %3\n" // temp = new_value
+ "sc %0, %2\n" // *ptr = temp (with atomic check)
+ "beqz %0, 1b\n" // start again on atomic error
+ "nop\n" // delay slot nop
+ ".set pop\n"
+ : "=&r" (temp), "=&r" (old), "=m" (*ptr)
+ : "r" (new_value), "m" (*ptr)
+ : "memory");
+
+ return old;
+}
+
+// Atomically increment *ptr by "increment". Returns the new value of
+// *ptr with the increment applied. This routine implies no memory barriers.
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+ Atomic32 increment) {
+ Atomic32 temp, temp2;
+
+ __asm__ __volatile__(".set push\n"
+ ".set noreorder\n"
+ "1:\n"
+ "ll %0, %2\n" // temp = *ptr
+ "addu %1, %0, %3\n" // temp2 = temp + increment
+ "sc %1, %2\n" // *ptr = temp2 (with atomic check)
+ "beqz %1, 1b\n" // start again on atomic error
+ "addu %1, %0, %3\n" // temp2 = temp + increment
+ ".set pop\n"
+ : "=&r" (temp), "=&r" (temp2), "=m" (*ptr)
+ : "Ir" (increment), "m" (*ptr)
+ : "memory");
+ // temp2 now holds the final value.
+ return temp2;
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+ Atomic32 increment) {
+ ATOMICOPS_COMPILER_BARRIER();
+ Atomic32 res = NoBarrier_AtomicIncrement(ptr, increment);
+ ATOMICOPS_COMPILER_BARRIER();
+ return res;
+}
+
+// "Acquire" operations
+// ensure that no later memory access can be reordered ahead of the operation.
+// "Release" operations ensure that no previous memory access can be reordered
+// after the operation. "Barrier" operations have both "Acquire" and "Release"
+// semantics. A MemoryBarrier() has "Barrier" semantics, but does no memory
+// access.
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ ATOMICOPS_COMPILER_BARRIER();
+ Atomic32 res = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+ ATOMICOPS_COMPILER_BARRIER();
+ return res;
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ ATOMICOPS_COMPILER_BARRIER();
+ Atomic32 res = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+ ATOMICOPS_COMPILER_BARRIER();
+ return res;
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+ *ptr = value;
+}
+
+inline void MemoryBarrier() {
+ __asm__ __volatile__("sync" : : : "memory");
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+ *ptr = value;
+ MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+ MemoryBarrier();
+ *ptr = value;
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+ return *ptr;
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+ Atomic32 value = *ptr;
+ MemoryBarrier();
+ return value;
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+ MemoryBarrier();
+ return *ptr;
+}
+
+} // namespace base::subtle
+} // namespace base
+
+#undef ATOMICOPS_COMPILER_BARRIER
+
+#endif // BASE_ATOMICOPS_INTERNALS_MIPS_GCC_H_