lavf: stop exporting internal functions
[ffmpeg.git] / compat / w32pthreads.h
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 FFmpeg.
8  *
9  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 FFMPEG_COMPAT_W32PTHREADS_H
30 #define FFMPEG_COMPAT_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
42 #include "libavutil/common.h"
43 #include "libavutil/internal.h"
44 #include "libavutil/mem.h"
45
46 typedef struct pthread_t {
47     void *handle;
48     void *(*func)(void* arg);
49     void *arg;
50     void *ret;
51 } pthread_t;
52
53 /* the conditional variable api for windows 6.0+ uses critical sections and
54  * not mutexes */
55 typedef CRITICAL_SECTION pthread_mutex_t;
56
57 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
58  * conditional variables on kernels 6.0+.
59  * MinGW does not currently have this typedef. */
60 typedef struct pthread_cond_t {
61     void *ptr;
62 } pthread_cond_t;
63
64 /* function pointers to conditional variable API on windows 6.0+ kernels */
65 #if _WIN32_WINNT < 0x0600
66 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
67 static void (WINAPI *cond_init)(pthread_cond_t *cond);
68 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
69 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
70                                 DWORD milliseconds);
71 #else
72 #define cond_init      InitializeConditionVariable
73 #define cond_broadcast WakeAllConditionVariable
74 #define cond_signal    WakeConditionVariable
75 #define cond_wait      SleepConditionVariableCS
76 #endif
77
78 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
79 {
80     pthread_t *h = arg;
81     h->ret = h->func(h->arg);
82     return 0;
83 }
84
85 static int pthread_create(pthread_t *thread, const void *unused_attr,
86                           void *(*start_routine)(void*), void *arg)
87 {
88     thread->func   = start_routine;
89     thread->arg    = arg;
90     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
91                                            0, NULL);
92     return !thread->handle;
93 }
94
95 static void pthread_join(pthread_t thread, void **value_ptr)
96 {
97     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
98     if (ret != WAIT_OBJECT_0)
99         return;
100     if (value_ptr)
101         *value_ptr = thread.ret;
102     CloseHandle(thread.handle);
103 }
104
105 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
106 {
107     InitializeCriticalSection(m);
108     return 0;
109 }
110 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
111 {
112     DeleteCriticalSection(m);
113     return 0;
114 }
115 static inline int pthread_mutex_lock(pthread_mutex_t *m)
116 {
117     EnterCriticalSection(m);
118     return 0;
119 }
120 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
121 {
122     LeaveCriticalSection(m);
123     return 0;
124 }
125
126 /* for pre-Windows 6.0 platforms we need to define and use our own condition
127  * variable and api */
128 typedef struct  win32_cond_t {
129     pthread_mutex_t mtx_broadcast;
130     pthread_mutex_t mtx_waiter_count;
131     volatile int waiter_count;
132     HANDLE semaphore;
133     HANDLE waiters_done;
134     volatile int is_broadcast;
135 } win32_cond_t;
136
137 static int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
138 {
139     win32_cond_t *win32_cond = NULL;
140     if (cond_init) {
141         cond_init(cond);
142         return 0;
143     }
144
145     /* non native condition variables */
146     win32_cond = av_mallocz(sizeof(win32_cond_t));
147     if (!win32_cond)
148         return ENOMEM;
149     cond->ptr = win32_cond;
150     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
151     if (!win32_cond->semaphore)
152         return ENOMEM;
153     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
154     if (!win32_cond->waiters_done)
155         return ENOMEM;
156
157     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
158     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
159     return 0;
160 }
161
162 static void pthread_cond_destroy(pthread_cond_t *cond)
163 {
164     win32_cond_t *win32_cond = cond->ptr;
165     /* native condition variables do not destroy */
166     if (cond_init)
167         return;
168
169     /* non native condition variables */
170     CloseHandle(win32_cond->semaphore);
171     CloseHandle(win32_cond->waiters_done);
172     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
173     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
174     av_freep(&win32_cond);
175     cond->ptr = NULL;
176 }
177
178 static void pthread_cond_broadcast(pthread_cond_t *cond)
179 {
180     win32_cond_t *win32_cond = cond->ptr;
181     int have_waiter;
182
183     if (cond_broadcast) {
184         cond_broadcast(cond);
185         return;
186     }
187
188     /* non native condition variables */
189     pthread_mutex_lock(&win32_cond->mtx_broadcast);
190     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
191     have_waiter = 0;
192
193     if (win32_cond->waiter_count) {
194         win32_cond->is_broadcast = 1;
195         have_waiter = 1;
196     }
197
198     if (have_waiter) {
199         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
200         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
201         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
202         ResetEvent(win32_cond->waiters_done);
203         win32_cond->is_broadcast = 0;
204     } else
205         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
206     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
207 }
208
209 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
210 {
211     win32_cond_t *win32_cond = cond->ptr;
212     int last_waiter;
213     if (cond_wait) {
214         cond_wait(cond, mutex, INFINITE);
215         return 0;
216     }
217
218     /* non native condition variables */
219     pthread_mutex_lock(&win32_cond->mtx_broadcast);
220     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
221     win32_cond->waiter_count++;
222     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
223     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
224
225     // unlock the external mutex
226     pthread_mutex_unlock(mutex);
227     WaitForSingleObject(win32_cond->semaphore, INFINITE);
228
229     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
230     win32_cond->waiter_count--;
231     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
232     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
233
234     if (last_waiter)
235         SetEvent(win32_cond->waiters_done);
236
237     // lock the external mutex
238     return pthread_mutex_lock(mutex);
239 }
240
241 static void pthread_cond_signal(pthread_cond_t *cond)
242 {
243     win32_cond_t *win32_cond = cond->ptr;
244     int have_waiter;
245     if (cond_signal) {
246         cond_signal(cond);
247         return;
248     }
249
250     pthread_mutex_lock(&win32_cond->mtx_broadcast);
251
252     /* non-native condition variables */
253     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
254     have_waiter = win32_cond->waiter_count;
255     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
256
257     if (have_waiter) {
258         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
259         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
260         ResetEvent(win32_cond->waiters_done);
261     }
262
263     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
264 }
265
266 static void w32thread_init(void)
267 {
268 #if _WIN32_WINNT < 0x0600
269     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
270     /* if one is available, then they should all be available */
271     cond_init      =
272         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
273     cond_broadcast =
274         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
275     cond_signal    =
276         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
277     cond_wait      =
278         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
279 #endif
280
281 }
282
283 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */