1/*
2 * $Id: pa_memorybarrier.h 1240 2007-07-17 13:05:07Z bjornroche $
3 * Portable Audio I/O Library
4 * Memory barrier utilities
5 *
6 * Author: Bjorn Roche, XO Audio, LLC
7 *
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
11 *
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:
19 *
20 * The above copyright notice and this permission notice shall be
21 * included in all copies or substantial portions of the Software.
22 *
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.
30 */
31
32/*
33 * The text above constitutes the entire PortAudio license; however,
34 * the PortAudio community also makes the following non-binding requests:
35 *
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
40 * license above.
41 */
42
43/**
44 @file pa_memorybarrier.h
45 @ingroup common_src
46*/
47
48/****************
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)
54 *
55 * the primitives that must be defined are:
56 *
57 * PaUtil_FullMemoryBarrier()
58 * PaUtil_ReadMemoryBarrier()
59 * PaUtil_WriteMemoryBarrier()
60 *
61 ****************/
62
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")
90#   else
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()
97#      else
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.
99#      endif
100#   endif
101#elif (_MSC_VER >= 1400) && !defined(_WIN32_WCE)
102#   include <intrin.h>
103#   pragma intrinsic(_ReadWriteBarrier)
104#   pragma intrinsic(_ReadBarrier)
105#   pragma intrinsic(_WriteBarrier)
106#   define PaUtil_FullMemoryBarrier()  _ReadWriteBarrier()
107#   define PaUtil_ReadMemoryBarrier()  _ReadBarrier()
108#   define PaUtil_WriteMemoryBarrier() _WriteBarrier()
109#elif defined(_WIN32_WCE)
110#   define PaUtil_FullMemoryBarrier()
111#   define PaUtil_ReadMemoryBarrier()
112#   define PaUtil_WriteMemoryBarrier()
113#elif defined(_MSC_VER) || defined(__BORLANDC__)
114#   define PaUtil_FullMemoryBarrier()  _asm { lock add    [esp], 0 }
115#   define PaUtil_ReadMemoryBarrier()  _asm { lock add    [esp], 0 }
116#   define PaUtil_WriteMemoryBarrier() _asm { lock add    [esp], 0 }
117#else
118#   ifdef ALLOW_SMP_DANGERS
119#      warning Memory barriers not defined on this system or system unknown
120#      warning For SMP safety, you should fix this.
121#      define PaUtil_FullMemoryBarrier()
122#      define PaUtil_ReadMemoryBarrier()
123#      define PaUtil_WriteMemoryBarrier()
124#   else
125#      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.
126#   endif
127#endif
128