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pa_memorybarrier.h
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pa_memorybarrier.h
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/*
* $Id: pa_memorybarrier.h 1240 2007-07-17 13:05:07Z bjornroche $
* Portable Audio I/O Library
* Memory barrier utilities
*
* Author: Bjorn Roche, XO Audio, LLC
*
* This program uses the PortAudio Portable Audio Library.
* For more information see: http://www.portaudio.com
* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* The text above constitutes the entire PortAudio license; however,
* the PortAudio community also makes the following non-binding requests:
*
* Any person wishing to distribute modifications to the Software is
* requested to send the modifications to the original developer so that
* they can be incorporated into the canonical version. It is also
* requested that these non-binding requests be included along with the
* license above.
*/
/**
@file pa_memorybarrier.h
@ingroup common_src
*/
/****************
* Some memory barrier primitives based on the system.
* right now only OS X, FreeBSD, and Linux are supported. In addition to providing
* memory barriers, these functions should ensure that data cached in registers
* is written out to cache where it can be snooped by other CPUs. (ie, the volatile
* keyword should not be required)
*
* the primitives that must be defined are:
*
* PaUtil_FullMemoryBarrier()
* PaUtil_ReadMemoryBarrier()
* PaUtil_WriteMemoryBarrier()
*
****************/
#if defined(__APPLE__)
# include <libkern/OSAtomic.h>
/* Here are the memory barrier functions. Mac OS X only provides
full memory barriers, so the three types of barriers are the same,
however, these barriers are superior to compiler-based ones. */
# define PaUtil_FullMemoryBarrier() OSMemoryBarrier()
# define PaUtil_ReadMemoryBarrier() OSMemoryBarrier()
# define PaUtil_WriteMemoryBarrier() OSMemoryBarrier()
#elif defined(__GNUC__)
/* GCC >= 4.1 has built-in intrinsics. We'll use those */
# if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
# define PaUtil_FullMemoryBarrier() __sync_synchronize()
# define PaUtil_ReadMemoryBarrier() __sync_synchronize()
# define PaUtil_WriteMemoryBarrier() __sync_synchronize()
/* as a fallback, GCC understands volatile asm and "memory" to mean it
* should not reorder memory read/writes */
/* Note that it is not clear that any compiler actually defines __PPC__,
* it can probably removed safely. */
# elif defined( __ppc__ ) || defined( __powerpc__) || defined( __PPC__ )
# define PaUtil_FullMemoryBarrier() asm volatile("sync":::"memory")
# define PaUtil_ReadMemoryBarrier() asm volatile("sync":::"memory")
# define PaUtil_WriteMemoryBarrier() asm volatile("sync":::"memory")
# elif defined( __i386__ ) || defined( __i486__ ) || defined( __i586__ ) || \
defined( __i686__ ) || defined( __x86_64__ )
# define PaUtil_FullMemoryBarrier() asm volatile("mfence":::"memory")
# define PaUtil_ReadMemoryBarrier() asm volatile("lfence":::"memory")
# define PaUtil_WriteMemoryBarrier() asm volatile("sfence":::"memory")
# else
# ifdef ALLOW_SMP_DANGERS
# warning Memory barriers not defined on this system or system unknown
# warning For SMP safety, you should fix this.
# define PaUtil_FullMemoryBarrier()
# define PaUtil_ReadMemoryBarrier()
# define PaUtil_WriteMemoryBarrier()
# else
# error Memory barriers are not defined on this system. You can still compile by defining ALLOW_SMP_DANGERS, but SMP safety will not be guaranteed.
# endif
# endif
#elif (_MSC_VER >= 1400) && !defined(_WIN32_WCE)
# include <intrin.h>
# pragma intrinsic(_ReadWriteBarrier)
# pragma intrinsic(_ReadBarrier)
# pragma intrinsic(_WriteBarrier)
/* note that MSVC intrinsics _ReadWriteBarrier(), _ReadBarrier(), _WriteBarrier() are just compiler barriers *not* memory barriers */
# define PaUtil_FullMemoryBarrier() _ReadWriteBarrier()
# define PaUtil_ReadMemoryBarrier() _ReadBarrier()
# define PaUtil_WriteMemoryBarrier() _WriteBarrier()
#elif defined(_WIN32_WCE)
# define PaUtil_FullMemoryBarrier()
# define PaUtil_ReadMemoryBarrier()
# define PaUtil_WriteMemoryBarrier()
#elif defined(_MSC_VER) || defined(__BORLANDC__)
# define PaUtil_FullMemoryBarrier() _asm { lock add [esp], 0 }
# define PaUtil_ReadMemoryBarrier() _asm { lock add [esp], 0 }
# define PaUtil_WriteMemoryBarrier() _asm { lock add [esp], 0 }
#else
# ifdef ALLOW_SMP_DANGERS
# warning Memory barriers not defined on this system or system unknown
# warning For SMP safety, you should fix this.
# define PaUtil_FullMemoryBarrier()
# define PaUtil_ReadMemoryBarrier()
# define PaUtil_WriteMemoryBarrier()
# else
# error Memory barriers are not defined on this system. You can still compile by defining ALLOW_SMP_DANGERS, but SMP safety will not be guaranteed.
# endif
#endif