w32pthreads: Add missing #includes to make header compile standalone
[ffmpeg.git] / libavcodec / 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 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
42 #include "libavutil/internal.h"
43 #include "libavutil/mem.h"
44
45 typedef struct {
46     void *handle;
47     void *(*func)(void* arg);
48     void *arg;
49     void *ret;
50 } pthread_t;
51
52 /* the conditional variable api for windows 6.0+ uses critical sections and
53  * not mutexes */
54 typedef CRITICAL_SECTION pthread_mutex_t;
55
56 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
57  * conditional variables on kernels 6.0+.
58  * MinGW does not currently have this typedef. */
59 typedef struct {
60     void *ptr;
61 } pthread_cond_t;
62
63 /* function pointers to conditional variable API on windows 6.0+ kernels */
64 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
65 static void (WINAPI *cond_init)(pthread_cond_t *cond);
66 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
67 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
68                                 DWORD milliseconds);
69
70 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
71 {
72     pthread_t *h = arg;
73     h->ret = h->func(h->arg);
74     return 0;
75 }
76
77 static int pthread_create(pthread_t *thread, const void *unused_attr,
78                           void *(*start_routine)(void*), void *arg)
79 {
80     thread->func   = start_routine;
81     thread->arg    = arg;
82     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
83                                            0, NULL);
84     return !thread->handle;
85 }
86
87 static void pthread_join(pthread_t thread, void **value_ptr)
88 {
89     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
90     if (ret != WAIT_OBJECT_0)
91         return;
92     if (value_ptr)
93         *value_ptr = thread.ret;
94     CloseHandle(thread.handle);
95 }
96
97 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
98 {
99     InitializeCriticalSection(m);
100     return 0;
101 }
102 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
103 {
104     DeleteCriticalSection(m);
105     return 0;
106 }
107 static inline int pthread_mutex_lock(pthread_mutex_t *m)
108 {
109     EnterCriticalSection(m);
110     return 0;
111 }
112 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
113 {
114     LeaveCriticalSection(m);
115     return 0;
116 }
117
118 /* for pre-Windows 6.0 platforms we need to define and use our own condition
119  * variable and api */
120 typedef struct {
121     pthread_mutex_t mtx_broadcast;
122     pthread_mutex_t mtx_waiter_count;
123     volatile int waiter_count;
124     HANDLE semaphore;
125     HANDLE waiters_done;
126     volatile int is_broadcast;
127 } win32_cond_t;
128
129 static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
130 {
131     win32_cond_t *win32_cond = NULL;
132     if (cond_init) {
133         cond_init(cond);
134         return;
135     }
136
137     /* non native condition variables */
138     win32_cond = av_mallocz(sizeof(win32_cond_t));
139     if (!win32_cond)
140         return;
141     cond->ptr = win32_cond;
142     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
143     if (!win32_cond->semaphore)
144         return;
145     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
146     if (!win32_cond->waiters_done)
147         return;
148
149     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
150     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
151 }
152
153 static void pthread_cond_destroy(pthread_cond_t *cond)
154 {
155     win32_cond_t *win32_cond = cond->ptr;
156     /* native condition variables do not destroy */
157     if (cond_init)
158         return;
159
160     /* non native condition variables */
161     CloseHandle(win32_cond->semaphore);
162     CloseHandle(win32_cond->waiters_done);
163     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
164     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
165     av_freep(&win32_cond);
166     cond->ptr = NULL;
167 }
168
169 static void pthread_cond_broadcast(pthread_cond_t *cond)
170 {
171     win32_cond_t *win32_cond = cond->ptr;
172     int have_waiter;
173
174     if (cond_broadcast) {
175         cond_broadcast(cond);
176         return;
177     }
178
179     /* non native condition variables */
180     pthread_mutex_lock(&win32_cond->mtx_broadcast);
181     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
182     have_waiter = 0;
183
184     if (win32_cond->waiter_count) {
185         win32_cond->is_broadcast = 1;
186         have_waiter = 1;
187     }
188
189     if (have_waiter) {
190         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
191         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
192         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
193         ResetEvent(win32_cond->waiters_done);
194         win32_cond->is_broadcast = 0;
195     } else
196         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
197     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
198 }
199
200 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
201 {
202     win32_cond_t *win32_cond = cond->ptr;
203     int last_waiter;
204     if (cond_wait) {
205         cond_wait(cond, mutex, INFINITE);
206         return 0;
207     }
208
209     /* non native condition variables */
210     pthread_mutex_lock(&win32_cond->mtx_broadcast);
211     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
212     win32_cond->waiter_count++;
213     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
214     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
215
216     // unlock the external mutex
217     pthread_mutex_unlock(mutex);
218     WaitForSingleObject(win32_cond->semaphore, INFINITE);
219
220     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
221     win32_cond->waiter_count--;
222     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
223     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
224
225     if (last_waiter)
226         SetEvent(win32_cond->waiters_done);
227
228     // lock the external mutex
229     return pthread_mutex_lock(mutex);
230 }
231
232 static void pthread_cond_signal(pthread_cond_t *cond)
233 {
234     win32_cond_t *win32_cond = cond->ptr;
235     int have_waiter;
236     if (cond_signal) {
237         cond_signal(cond);
238         return;
239     }
240
241     pthread_mutex_lock(&win32_cond->mtx_broadcast);
242
243     /* non-native condition variables */
244     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
245     have_waiter = win32_cond->waiter_count;
246     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
247
248     if (have_waiter) {
249         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
250         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
251         ResetEvent(win32_cond->waiters_done);
252     }
253
254     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
255 }
256
257 static void w32thread_init(void)
258 {
259     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
260     /* if one is available, then they should all be available */
261     cond_init      =
262         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
263     cond_broadcast =
264         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
265     cond_signal    =
266         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
267     cond_wait      =
268         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
269 }
270
271 #endif /* AVCODEC_W32PTHREADS_H */