/*
 * $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()
 *
 ****************/

#ifndef MODULES_THIRD_PARTY_PORTAUDIO_PA_MEMORYBARRIER_H_
#define MODULES_THIRD_PARTY_PORTAUDIO_PA_MEMORYBARRIER_H_

#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)
#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

#endif /* MODULES_THIRD_PARTY_PORTAUDIO_PA_MEMORYBARRIER_H_ */