FFmpeg: compat/w32pthreads.h Source File

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compat

w32pthreads.h

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1 /*

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 */

24 /**

25 * @file

26 * w32threads to pthreads wrapper

27 */

29 #ifndef FFMPEG_COMPAT_W32PTHREADS_H

30 #define FFMPEG_COMPAT_W32PTHREADS_H

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. */

38 #define WIN32_LEAN_AND_MEAN

39 #include <windows.h>

40 #include <process.h>

42 #include "libavutil/attributes.h"

43 #include "libavutil/common.h"

44 #include "libavutil/internal.h"

45 #include "libavutil/mem.h"

47 typedef struct pthread_t {

48 void *handle;

49 void *(*func)(void* arg);

50 void *arg;

51 void *ret;

52 } pthread_t;

54 /* the conditional variable api for windows 6.0+ uses critical sections and

55 * not mutexes */

56 typedef CRITICAL_SECTION pthread_mutex_t;

58 /* This is the CONDITION_VARIABLE typedef for using Windows' native

59 * conditional variables on kernels 6.0+. */

60 #if HAVE_CONDITION_VARIABLE_PTR

61 typedef CONDITION_VARIABLE pthread_cond_t;

62 #else

63 typedef struct pthread_cond_t {

64 void *Ptr;

65 } pthread_cond_t;

66 #endif

68 #if _WIN32_WINNT >= 0x0600

69 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)

70 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)

71 #endif

73 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)

74 {

75 pthread_t *h = arg;

76 h->ret = h->func(h->arg);

77 return 0;

78 }

80 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,

81 void *(*start_routine)(void*), void *arg)

82 {

83 thread->func = start_routine;

84 thread->arg = arg;

85 thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,

86 0, NULL);

87 return !thread->handle;

88 }

90 static av_unused void pthread_join(pthread_t thread, void **value_ptr)

91 {

92 DWORD ret = WaitForSingleObject(thread.handle, INFINITE);

93 if (ret != WAIT_OBJECT_0)

94 return;

95 if (value_ptr)

96 *value_ptr = thread.ret;

97 CloseHandle(thread.handle);

98 }

100 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)

101 {

102 InitializeCriticalSection(m);

103 return 0;

104 }

105 static inline int pthread_mutex_destroy(pthread_mutex_t *m)

106 {

107 DeleteCriticalSection(m);

108 return 0;

109 }

110 static inline int pthread_mutex_lock(pthread_mutex_t *m)

111 {

112 EnterCriticalSection(m);

113 return 0;

114 }

115 static inline int pthread_mutex_unlock(pthread_mutex_t *m)

116 {

117 LeaveCriticalSection(m);

118 return 0;

119 }

120

121 #if _WIN32_WINNT >= 0x0600

122 static inline int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)

123 {

124 InitializeConditionVariable(cond);

125 return 0;

126 }

127

128 /* native condition variables do not destroy */

129 static inline void pthread_cond_destroy(pthread_cond_t *cond)

130 {

131 return;

132 }

133

134 static inline void pthread_cond_broadcast(pthread_cond_t *cond)

135 {

136 WakeAllConditionVariable(cond);

137 }

138

139 static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)

140 {

141 SleepConditionVariableCS(cond, mutex, INFINITE);

142 return 0;

143 }

144

145 static inline void pthread_cond_signal(pthread_cond_t *cond)

146 {

147 WakeConditionVariable(cond);

148 }

149

150 #else // _WIN32_WINNT < 0x0600

151 /* for pre-Windows 6.0 platforms we need to define and use our own condition

152 * variable and api */

153 typedef struct win32_cond_t {

154 pthread_mutex_t mtx_broadcast;

155 pthread_mutex_t mtx_waiter_count;

156 volatile int waiter_count;

157 HANDLE semaphore;

158 HANDLE waiters_done;

159 volatile int is_broadcast;

160 } win32_cond_t;

161

162 /* function pointers to conditional variable API on windows 6.0+ kernels */

163 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);

164 static void (WINAPI *cond_init)(pthread_cond_t *cond);

165 static void (WINAPI *cond_signal)(pthread_cond_t *cond);

166 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,

167 DWORD milliseconds);

168

169 static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)

170 {

171 win32_cond_t *win32_cond = NULL;

172 if (cond_init) {

173 cond_init(cond);

174 return 0;

175 }

176

177 /* non native condition variables */

178 win32_cond = av_mallocz(sizeof(win32_cond_t));

179 if (!win32_cond)

180 return ENOMEM;

181 cond->Ptr = win32_cond;

182 win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);

183 if (!win32_cond->semaphore)

184 return ENOMEM;

185 win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);

186 if (!win32_cond->waiters_done)

187 return ENOMEM;

188

189 pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);

190 pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);

191 return 0;

192 }

193

194 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)

195 {

196 win32_cond_t *win32_cond = cond->Ptr;

197 /* native condition variables do not destroy */

198 if (cond_init)

199 return;

200

201 /* non native condition variables */

202 CloseHandle(win32_cond->semaphore);

203 CloseHandle(win32_cond->waiters_done);

204 pthread_mutex_destroy(&win32_cond->mtx_waiter_count);

205 pthread_mutex_destroy(&win32_cond->mtx_broadcast);

206 av_freep(&win32_cond);

207 cond->Ptr = NULL;

208 }

209

210 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)

211 {

212 win32_cond_t *win32_cond = cond->Ptr;

213 int have_waiter;

214

215 if (cond_broadcast) {

216 cond_broadcast(cond);

217 return;

218 }

219

220 /* non native condition variables */

221 pthread_mutex_lock(&win32_cond->mtx_broadcast);

222 pthread_mutex_lock(&win32_cond->mtx_waiter_count);

223 have_waiter = 0;

224

225 if (win32_cond->waiter_count) {

226 win32_cond->is_broadcast = 1;

227 have_waiter = 1;

228 }

229

230 if (have_waiter) {

231 ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);

232 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

233 WaitForSingleObject(win32_cond->waiters_done, INFINITE);

234 ResetEvent(win32_cond->waiters_done);

235 win32_cond->is_broadcast = 0;

236 } else

237 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

238 pthread_mutex_unlock(&win32_cond->mtx_broadcast);

239 }

240

241 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)

242 {

243 win32_cond_t *win32_cond = cond->Ptr;

244 int last_waiter;

245 if (cond_wait) {

246 cond_wait(cond, mutex, INFINITE);

247 return 0;

248 }

249

250 /* non native condition variables */

251 pthread_mutex_lock(&win32_cond->mtx_broadcast);

252 pthread_mutex_lock(&win32_cond->mtx_waiter_count);

253 win32_cond->waiter_count++;

254 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

255 pthread_mutex_unlock(&win32_cond->mtx_broadcast);

256

257 // unlock the external mutex

258 pthread_mutex_unlock(mutex);

259 WaitForSingleObject(win32_cond->semaphore, INFINITE);

260

261 pthread_mutex_lock(&win32_cond->mtx_waiter_count);

262 win32_cond->waiter_count--;

263 last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;

264 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

265

266 if (last_waiter)

267 SetEvent(win32_cond->waiters_done);

268

269 // lock the external mutex

270 return pthread_mutex_lock(mutex);

271 }

272

273 static av_unused void pthread_cond_signal(pthread_cond_t *cond)

274 {

275 win32_cond_t *win32_cond = cond->Ptr;

276 int have_waiter;

277 if (cond_signal) {

278 cond_signal(cond);

279 return;

280 }

281

282 pthread_mutex_lock(&win32_cond->mtx_broadcast);

283

284 /* non-native condition variables */

285 pthread_mutex_lock(&win32_cond->mtx_waiter_count);

286 have_waiter = win32_cond->waiter_count;

287 pthread_mutex_unlock(&win32_cond->mtx_waiter_count);

288

289 if (have_waiter) {

290 ReleaseSemaphore(win32_cond->semaphore, 1, NULL);

291 WaitForSingleObject(win32_cond->waiters_done, INFINITE);

292 ResetEvent(win32_cond->waiters_done);

293 }

294

295 pthread_mutex_unlock(&win32_cond->mtx_broadcast);

296 }

297 #endif

298

299 static av_unused void w32thread_init(void)

300 {

301 #if _WIN32_WINNT < 0x0600

302 HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));

303 /* if one is available, then they should all be available */

304 cond_init =

305 (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");

306 cond_broadcast =

307 (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");

308 cond_signal =

309 (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");

310 cond_wait =

311 (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");

312 #endif

313

314 }

315

316 #endif /* FFMPEG_COMPAT_W32PTHREADS_H */

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