fcmutex.h revision c9710b42 
1/*
2 * Atomic int and pointer operations.  Originally copied from HarfBuzz.
3 *
4 * Copyright © 2007  Chris Wilson
5 * Copyright © 2009,2010  Red Hat, Inc.
6 * Copyright © 2011,2012,2013  Google, Inc.
7 *
8 * Permission is hereby granted, without written agreement and without
9 * license or royalty fees, to use, copy, modify, and distribute this
10 * software and its documentation for any purpose, provided that the
11 * above copyright notice and the following two paragraphs appear in
12 * all copies of this software.
13 *
14 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
15 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
16 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
17 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
18 * DAMAGE.
19 *
20 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
21 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
22 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
23 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
24 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
25 *
26 * Contributor(s):
27 *	Chris Wilson <chris@chris-wilson.co.uk>
28 * Red Hat Author(s): Behdad Esfahbod
29 * Google Author(s): Behdad Esfahbod
30 */
31
32#ifndef _FCMUTEX_H_
33#define _FCMUTEX_H_
34
35#ifdef HAVE_CONFIG_H
36#include <config.h>
37#endif
38
39#define FC_STMT_START do
40#define FC_STMT_END while (0)
41
42/* mutex */
43
44/* We need external help for these */
45
46#if 0
47
48
49#elif !defined(FC_NO_MT) && defined(_MSC_VER) || defined(__MINGW32__)
50
51#include "fcwindows.h"
52typedef CRITICAL_SECTION fc_mutex_impl_t;
53#define FC_MUTEX_IMPL_INIT	{ NULL, 0, 0, NULL, NULL, 0 }
54#define fc_mutex_impl_init(M)	InitializeCriticalSection (M)
55#define fc_mutex_impl_lock(M)	EnterCriticalSection (M)
56#define fc_mutex_impl_unlock(M)	LeaveCriticalSection (M)
57#define fc_mutex_impl_finish(M)	DeleteCriticalSection (M)
58
59
60#elif !defined(FC_NO_MT) && (defined(HAVE_PTHREAD) || defined(__APPLE__))
61
62#include <pthread.h>
63typedef pthread_mutex_t fc_mutex_impl_t;
64#define FC_MUTEX_IMPL_INIT	PTHREAD_MUTEX_INITIALIZER
65#define fc_mutex_impl_init(M)	pthread_mutex_init (M, NULL)
66#define fc_mutex_impl_lock(M)	pthread_mutex_lock (M)
67#define fc_mutex_impl_unlock(M)	pthread_mutex_unlock (M)
68#define fc_mutex_impl_finish(M)	pthread_mutex_destroy (M)
69
70
71#elif !defined(FC_NO_MT) && defined(HAVE_INTEL_ATOMIC_PRIMITIVES)
72
73#if defined(HAVE_SCHED_H) && defined(HAVE_SCHED_YIELD)
74# include <sched.h>
75# define FC_SCHED_YIELD() sched_yield ()
76#else
77# define FC_SCHED_YIELD() FC_STMT_START {} FC_STMT_END
78#endif
79
80/* This actually is not a totally awful implementation. */
81typedef volatile int fc_mutex_impl_t;
82#define FC_MUTEX_IMPL_INIT	0
83#define fc_mutex_impl_init(M)	*(M) = 0
84#define fc_mutex_impl_lock(M)	FC_STMT_START { while (__sync_lock_test_and_set((M), 1)) FC_SCHED_YIELD (); } FC_STMT_END
85#define fc_mutex_impl_unlock(M)	__sync_lock_release (M)
86#define fc_mutex_impl_finish(M)	FC_STMT_START {} FC_STMT_END
87
88
89#elif !defined(FC_NO_MT)
90
91#if defined(HAVE_SCHED_H) && defined(HAVE_SCHED_YIELD)
92# include <sched.h>
93# define FC_SCHED_YIELD() sched_yield ()
94#else
95# define FC_SCHED_YIELD() FC_STMT_START {} FC_STMT_END
96#endif
97
98#define FC_MUTEX_INT_NIL 1 /* Warn that fallback implementation is in use. */
99typedef volatile int fc_mutex_impl_t;
100#define FC_MUTEX_IMPL_INIT	0
101#define fc_mutex_impl_init(M)	*(M) = 0
102#define fc_mutex_impl_lock(M)	FC_STMT_START { while (*(M)) FC_SCHED_YIELD (); (*(M))++; } FC_STMT_END
103#define fc_mutex_impl_unlock(M)	(*(M))--;
104#define fc_mutex_impl_finish(M)	FC_STMT_START {} FC_STMT_END
105
106
107#else /* FC_NO_MT */
108
109typedef int fc_mutex_impl_t;
110#define FC_MUTEX_IMPL_INIT	0
111#define fc_mutex_impl_init(M)	FC_STMT_START {} FC_STMT_END
112#define fc_mutex_impl_lock(M)	FC_STMT_START {} FC_STMT_END
113#define fc_mutex_impl_unlock(M)	FC_STMT_START {} FC_STMT_END
114#define fc_mutex_impl_finish(M)	FC_STMT_START {} FC_STMT_END
115
116#endif
117
118
119#define FC_MUTEX_INIT		{FC_MUTEX_IMPL_INIT}
120typedef fc_mutex_impl_t FcMutex;
121static inline void FcMutexInit   (FcMutex *m) { fc_mutex_impl_init (m);   }
122static inline void FcMutexLock   (FcMutex *m) { fc_mutex_impl_lock (m);   }
123static inline void FcMutexUnlock (FcMutex *m) { fc_mutex_impl_unlock (m); }
124static inline void FcMutexFinish (FcMutex *m) { fc_mutex_impl_finish (m); }
125
126
127#endif /* _FCMUTEX_H_ */
128