2
* $Id: pa_memorybarrier.h 1240 2007-07-17 13:05:07Z bjornroche $
3
* Portable Audio I/O Library
4
* Memory barrier utilities
6
* Author: Bjorn Roche, XO Audio, LLC
8
* This program uses the PortAudio Portable Audio Library.
9
* For more information see: http://www.portaudio.com
10
* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
12
* Permission is hereby granted, free of charge, to any person obtaining
13
* a copy of this software and associated documentation files
14
* (the "Software"), to deal in the Software without restriction,
15
* including without limitation the rights to use, copy, modify, merge,
16
* publish, distribute, sublicense, and/or sell copies of the Software,
17
* and to permit persons to whom the Software is furnished to do so,
18
* subject to the following conditions:
20
* The above copyright notice and this permission notice shall be
21
* included in all copies or substantial portions of the Software.
23
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
26
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
27
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
28
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
29
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
33
* The text above constitutes the entire PortAudio license; however,
34
* the PortAudio community also makes the following non-binding requests:
36
* Any person wishing to distribute modifications to the Software is
37
* requested to send the modifications to the original developer so that
38
* they can be incorporated into the canonical version. It is also
39
* requested that these non-binding requests be included along with the
44
@file pa_memorybarrier.h
49
* Some memory barrier primitives based on the system.
50
* right now only OS X, FreeBSD, and Linux are supported. In addition to providing
51
* memory barriers, these functions should ensure that data cached in registers
52
* is written out to cache where it can be snooped by other CPUs. (ie, the volatile
53
* keyword should not be required)
55
* the primitives that must be defined are:
57
* PaUtil_FullMemoryBarrier()
58
* PaUtil_ReadMemoryBarrier()
59
* PaUtil_WriteMemoryBarrier()
63
#if defined(__APPLE__)
64
# include <libkern/OSAtomic.h>
65
/* Here are the memory barrier functions. Mac OS X only provides
66
full memory barriers, so the three types of barriers are the same,
67
however, these barriers are superior to compiler-based ones. */
68
# define PaUtil_FullMemoryBarrier() OSMemoryBarrier()
69
# define PaUtil_ReadMemoryBarrier() OSMemoryBarrier()
70
# define PaUtil_WriteMemoryBarrier() OSMemoryBarrier()
71
#elif defined(__GNUC__)
72
/* GCC >= 4.1 has built-in intrinsics. We'll use those */
73
# if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
74
# define PaUtil_FullMemoryBarrier() __sync_synchronize()
75
# define PaUtil_ReadMemoryBarrier() __sync_synchronize()
76
# define PaUtil_WriteMemoryBarrier() __sync_synchronize()
77
/* as a fallback, GCC understands volatile asm and "memory" to mean it
78
* should not reorder memory read/writes */
79
/* Note that it is not clear that any compiler actually defines __PPC__,
80
* it can probably removed safely. */
81
# elif defined( __ppc__ ) || defined( __powerpc__) || defined( __PPC__ )
82
# define PaUtil_FullMemoryBarrier() asm volatile("sync":::"memory")
83
# define PaUtil_ReadMemoryBarrier() asm volatile("sync":::"memory")
84
# define PaUtil_WriteMemoryBarrier() asm volatile("sync":::"memory")
85
# elif defined( __i386__ ) || defined( __i486__ ) || defined( __i586__ ) || \
86
defined( __i686__ ) || defined( __x86_64__ )
87
# define PaUtil_FullMemoryBarrier() asm volatile("mfence":::"memory")
88
# define PaUtil_ReadMemoryBarrier() asm volatile("lfence":::"memory")
89
# define PaUtil_WriteMemoryBarrier() asm volatile("sfence":::"memory")
91
# ifdef ALLOW_SMP_DANGERS
92
# warning Memory barriers not defined on this system or system unknown
93
# warning For SMP safety, you should fix this.
94
# define PaUtil_FullMemoryBarrier()
95
# define PaUtil_ReadMemoryBarrier()
96
# define PaUtil_WriteMemoryBarrier()
98
# 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.
101
#elif (_MSC_VER >= 1400) && !defined(_WIN32_WCE)
103
# pragma intrinsic(_ReadWriteBarrier)
104
# pragma intrinsic(_ReadBarrier)
105
# pragma intrinsic(_WriteBarrier)
106
/* note that MSVC intrinsics _ReadWriteBarrier(), _ReadBarrier(), _WriteBarrier() are just compiler barriers *not* memory barriers */
107
# define PaUtil_FullMemoryBarrier() _ReadWriteBarrier()
108
# define PaUtil_ReadMemoryBarrier() _ReadBarrier()
109
# define PaUtil_WriteMemoryBarrier() _WriteBarrier()
110
#elif defined(_WIN32_WCE)
111
# define PaUtil_FullMemoryBarrier()
112
# define PaUtil_ReadMemoryBarrier()
113
# define PaUtil_WriteMemoryBarrier()
114
#elif defined(_MSC_VER) || defined(__BORLANDC__)
115
# define PaUtil_FullMemoryBarrier() _asm { lock add [esp], 0 }
116
# define PaUtil_ReadMemoryBarrier() _asm { lock add [esp], 0 }
117
# define PaUtil_WriteMemoryBarrier() _asm { lock add [esp], 0 }
119
# ifdef ALLOW_SMP_DANGERS
120
# warning Memory barriers not defined on this system or system unknown
121
# warning For SMP safety, you should fix this.
122
# define PaUtil_FullMemoryBarrier()
123
# define PaUtil_ReadMemoryBarrier()
124
# define PaUtil_WriteMemoryBarrier()
126
# 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.