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[libav.git] / libavcodec / w32pthreads.h
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1/*
2 * Copyright (C) 2010-2011 x264 project
3 *
4 * Authors: Steven Walters <kemuri9@gmail.com>
5 * Pegasys Inc. <http://www.pegasys-inc.com>
6 *
7 * This file is part of Libav.
8 *
9 * Libav is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * Libav is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with Libav; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24/**
25 * @file
26 * w32threads to pthreads wrapper
27 */
28
29#ifndef AVCODEC_W32PTHREADS_H
30#define AVCODEC_W32PTHREADS_H
31
32/* Build up a pthread-like API using underlying Windows API. Have only static
33 * methods so as to not conflict with a potentially linked in pthread-win32
34 * library.
35 * As most functions here are used without checking return values,
36 * only implement return values as necessary. */
37
38#define WIN32_LEAN_AND_MEAN
39#include <windows.h>
40#include <process.h>
41
42typedef struct {
43 void *handle;
44 void *(*func)(void* arg);
45 void *arg;
46 void *ret;
47} pthread_t;
48
49/* the conditional variable api for windows 6.0+ uses critical sections and
50 * not mutexes */
51typedef CRITICAL_SECTION pthread_mutex_t;
52
53/* This is the CONDITIONAL_VARIABLE typedef for using Window's native
54 * conditional variables on kernels 6.0+.
55 * MinGW does not currently have this typedef. */
56typedef struct {
57 void *ptr;
58} pthread_cond_t;
59
60/* function pointers to conditional variable API on windows 6.0+ kernels */
61static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
62static void (WINAPI *cond_init)(pthread_cond_t *cond);
63static void (WINAPI *cond_signal)(pthread_cond_t *cond);
64static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
65 DWORD milliseconds);
66
67static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
68{
69 pthread_t *h = arg;
70 h->ret = h->func(h->arg);
71 return 0;
72}
73
74static int pthread_create(pthread_t *thread, const void *unused_attr,
75 void *(*start_routine)(void*), void *arg)
76{
77 thread->func = start_routine;
78 thread->arg = arg;
79 thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
80 0, NULL);
81 return !thread->handle;
82}
83
84static void pthread_join(pthread_t thread, void **value_ptr)
85{
86 DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
87 if (ret != WAIT_OBJECT_0)
88 return;
89 if (value_ptr)
90 *value_ptr = thread.ret;
91 CloseHandle(thread.handle);
92}
93
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94static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
95{
96 InitializeCriticalSection(m);
97 return 0;
98}
99static inline int pthread_mutex_destroy(pthread_mutex_t *m)
100{
101 DeleteCriticalSection(m);
102 return 0;
103}
104static inline int pthread_mutex_lock(pthread_mutex_t *m)
105{
106 EnterCriticalSection(m);
107 return 0;
108}
109static inline int pthread_mutex_unlock(pthread_mutex_t *m)
110{
111 LeaveCriticalSection(m);
112 return 0;
113}
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114
115/* for pre-Windows 6.0 platforms we need to define and use our own condition
116 * variable and api */
117typedef struct {
118 pthread_mutex_t mtx_waiter_count;
119 volatile int waiter_count;
120 HANDLE semaphore;
121} win32_cond_t;
122
123static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
124{
125 win32_cond_t *win32_cond = NULL;
126 if (cond_init) {
127 cond_init(cond);
128 return;
129 }
130
131 /* non native condition variables */
132 win32_cond = av_mallocz(sizeof(win32_cond_t));
133 if (!win32_cond)
134 return;
135 cond->ptr = win32_cond;
136 win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
137 if (!win32_cond->semaphore)
138 return;
139
140 pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
141}
142
143static void pthread_cond_destroy(pthread_cond_t *cond)
144{
145 win32_cond_t *win32_cond = cond->ptr;
146 /* native condition variables do not destroy */
147 if (cond_init)
148 return;
149
150 /* non native condition variables */
151 CloseHandle(win32_cond->semaphore);
152 pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
153 av_freep(&win32_cond);
154 cond->ptr = NULL;
155}
156
157static void pthread_cond_broadcast(pthread_cond_t *cond)
158{
159 win32_cond_t *win32_cond = cond->ptr;
160 if (cond_broadcast) {
161 cond_broadcast(cond);
162 return;
163 }
164
165 /* non native condition variables */
166 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
167 if (win32_cond->waiter_count) {
168 ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
169 win32_cond->waiter_count = 0;
170 }
171 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
172}
173
174static void pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
175{
176 win32_cond_t *win32_cond = cond->ptr;
177 if (cond_wait) {
178 cond_wait(cond, mutex, INFINITE);
179 return;
180 }
181
182 /* non native condition variables */
183 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
184 win32_cond->waiter_count++;
185 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
186
187 pthread_mutex_unlock(mutex);
188 WaitForSingleObject(win32_cond->semaphore, INFINITE);
189 pthread_mutex_lock(mutex);
190}
191
192static void pthread_cond_signal(pthread_cond_t *cond)
193{
194 win32_cond_t *win32_cond = cond->ptr;
195 if (cond_signal) {
196 cond_signal(cond);
197 return;
198 }
199
200 /* non-native condition variables */
201 pthread_mutex_lock(&win32_cond->mtx_waiter_count);
202 if (win32_cond->waiter_count) {
203 ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
204 win32_cond->waiter_count--;
205 }
206 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
207}
208
209static void w32thread_init(void)
210{
211 HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
212 /* if one is available, then they should all be available */
213 cond_init =
214 (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
215 cond_broadcast =
216 (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
217 cond_signal =
218 (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
219 cond_wait =
220 (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
221}
222
223#endif /* AVCODEC_W32PTHREADS_H */