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spinlock.cuh
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Sun, Nov 24, 17:53

spinlock.cuh
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/******************************************************************************
* Copyright (c) 2011, Duane Merrill. All rights reserved.
* Copyright (c) 2011-2013, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the NVIDIA CORPORATION nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************/
/**
* \file
* Simple x86/x64 atomic spinlock, portable across MS Windows (cl.exe) & Linux (g++)
*/
#pragma once
#if defined(_WIN32) || defined(_WIN64)
#include <intrin.h>
#include <windows.h>
#undef small // Windows is terrible for polluting macro namespace
/**
* Compiler read/write barrier
*/
#pragma intrinsic(_ReadWriteBarrier)
#endif
#include "../util_namespace.cuh"
/// Optional outer namespace(s)
CUB_NS_PREFIX
/// CUB namespace
namespace cub {
#if defined(_MSC_VER)
// Microsoft VC++
typedef long Spinlock;
#else
// GNU g++
typedef int Spinlock;
/**
* Compiler read/write barrier
*/
__forceinline__ void _ReadWriteBarrier()
{
__sync_synchronize();
}
/**
* Atomic exchange
*/
__forceinline__ long _InterlockedExchange(volatile int * const Target, const int Value)
{
// NOTE: __sync_lock_test_and_set would be an acquire barrier, so we force a full barrier
_ReadWriteBarrier();
return __sync_lock_test_and_set(Target, Value);
}
/**
* Pause instruction to prevent excess processor bus usage
*/
__forceinline__ void YieldProcessor()
{
#ifndef __arm__
asm volatile("pause\n": : :"memory");
#endif // __arm__
}
#endif // defined(_MSC_VER)
/**
* Return when the specified spinlock has been acquired
*/
__forceinline__ void Lock(volatile Spinlock *lock)
{
while (1)
{
if (!_InterlockedExchange(lock, 1)) return;
while (*lock) YieldProcessor();
}
}
/**
* Release the specified spinlock
*/
__forceinline__ void Unlock(volatile Spinlock *lock)
{
_ReadWriteBarrier();
*lock = 0;
}
} // CUB namespace
CUB_NS_POSTFIX // Optional outer namespace(s)

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