/*
ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
/*
Concepts and parts of this file are contributed by and Copyright (C) 2008
of Leon Woestenberg.
*/
/**
* @file chcond.c
* @brief Condition Variables code.
* @addtogroup CondVars
* @{
*/
#include
#if CH_USE_CONDVARS && CH_USE_MUTEXES
/**
* @brief Initializes s @p CondVar structure.
*
* @param[out] cp pointer to a @p CondVar structure
* @note This function can be invoked from within an interrupt handler even if
* it is not an I-Class API because it does not touch any critical kernel
* data structure.
*/
void chCondInit(CondVar *cp) {
chDbgCheck(cp != NULL, "chCondInit");
queue_init(&cp->c_queue);
}
/**
* @brief Signals one thread that is waiting on the condition variable.
*
* @param[in] cp pointer to the @p CondVar structure
*/
void chCondSignal(CondVar *cp) {
chDbgCheck(cp != NULL, "chCondSignal");
chSysLock();
if (notempty(&cp->c_queue)) /* any thread ? */
chSchWakeupS(fifo_remove(&cp->c_queue), RDY_OK);
chSysUnlock();
}
/**
* @brief Signals one thread that is waiting on the condition variable.
*
* @param[in] cp pointer to the @p CondVar structure
*/
void chCondSignalI(CondVar *cp) {
chDbgCheck(cp != NULL, "chCondSignalI");
if (notempty(&cp->c_queue)) /* any thread ? */
chSchReadyI(fifo_remove(&cp->c_queue))->p_rdymsg = RDY_OK;
}
/**
* @brief Signals all threads that are waiting on the condition variable.
*
* @param[in] cp pointer to the @p CondVar structure
*/
void chCondBroadcast(CondVar *cp) {
chSysLock();
chCondBroadcastI(cp);
chSchRescheduleS();
chSysUnlock();
}
/**
* @brief Signals all threads that are waiting on the condition variable.
*
* @param[in] cp pointer to the @p CondVar structure
*/
void chCondBroadcastI(CondVar *cp) {
chDbgCheck(cp != NULL, "chCondBroadcastI");
/* empties the condition variable queue and inserts all the Threads into the
* ready list in FIFO order. The wakeup message is set to @p RDY_RESET in
* order to make a chCondBroadcast() detectable from a chCondSignal(). */
while (cp->c_queue.p_next != (void *)&cp->c_queue)
chSchReadyI(fifo_remove(&cp->c_queue))->p_rdymsg = RDY_RESET;
}
/**
* @brief Waits on the condition variable releasing the mutex lock.
* @details Releases the mutex, waits on the condition variable, and finally
* acquires the mutex again. This is done atomically.
*
* @param[in] cp pointer to the @p CondVar structure
* @return The wakep mode.
* @retval RDY_OK if the condvar was signaled using chCondSignal().
* @retval RDY_RESET if the condvar was signaled using chCondBroadcast().
* @note The thread MUST already have locked the mutex when calling
* @p chCondWait().
*/
msg_t chCondWait(CondVar *cp) {
msg_t msg;
chSysLock();
msg = chCondWaitS(cp);
chSysUnlock();
return msg;
}
/**
* @brief Waits on the condition variable releasing the mutex lock.
* @details Releases the mutex, waits on the condition variable, and finally
* acquires the mutex again. This is done atomically.
*
* @param[in] cp pointer to the @p CondVar structure
* @return The wakep mode.
* @retval RDY_OK if the condvar was signaled using chCondSignal().
* @retval RDY_RESET if the condvar was signaled using chCondBroadcast().
* @note The thread MUST already have locked the mutex when calling
* @p chCondWaitS().
*/
msg_t chCondWaitS(CondVar *cp) {
Mutex *mp;
msg_t msg;
chDbgCheck(cp != NULL, "chCondWaitS");
chDbgAssert(currp->p_mtxlist != NULL,
"chCondWaitS(), #1",
"not owning a mutex");
mp = chMtxUnlockS(); /* unlocks the condvar mutex */
prio_insert(currp, &cp->c_queue); /* enters the condvar queue */
currp->p_wtcondp = cp; /* needed by the tracer */
chSchGoSleepS(PRWTCOND); /* waits on the condvar */
msg = currp->p_rdymsg; /* fetches the wakeup message */
chMtxLockS(mp); /* atomically relocks the mutex */
return msg; /* returns the wakeup message */
}
#if CH_USE_CONDVARS_TIMEOUT
/**
* @brief Waits on the condition variable releasing the mutex lock.
* @details Releases the mutex, waits on the condition variable, and finally
* acquires the mutex again. This is done atomically.
*
* @param[in] cp pointer to the @p CondVar structure
* @param[in] time the number of ticks before the operation timeouts,
* the special value @p TIME_INFINITE is allowed.
* It is not possible to specify zero @p TIME_IMMEDIATE
* as timeout specification because it would make no sense
* in this function.
* @return The wakep mode.
* @retval RDY_OK if the condvar was signaled using chCondSignal().
* @retval RDY_RESET if the condvar was signaled using chCondBroadcast().
* @retval RDY_TIMEOUT if the condvar was not signaled within the specified
* timeout.
* @note The thread MUST already have locked the mutex when calling
* @p chCondWaitTimeout().
*/
msg_t chCondWaitTimeout(CondVar *cp, systime_t time) {
msg_t msg;
chSysLock();
msg = chCondWaitTimeoutS(cp, time);
chSysUnlock();
return msg;
}
/**
* @brief Waits on the condition variable releasing the mutex lock.
* @details Releases the mutex, waits on the condition variable, and finally
* acquires the mutex again. This is done atomically.
*
* @param[in] cp pointer to the @p CondVar structure
* @param[in] time the number of ticks before the operation timeouts,
* the special value @p TIME_INFINITE is allowed.
* It is not possible to specify zero @p TIME_IMMEDIATE
* as timeout specification because it would make no sense
* in this function.
* @return The wakep mode.
* @retval RDY_OK if the condvar was signaled using chCondSignal().
* @retval RDY_RESET if the condvar was signaled using chCondBroadcast().
* @retval RDY_TIMEOUT if the condvar was not signaled within the specified
* timeout.
* @note The thread MUST already have locked the mutex when calling
* @p chCondWaitTimeoutS().
*/
msg_t chCondWaitTimeoutS(CondVar *cp, systime_t time) {
Mutex *mp;
msg_t msg;
chDbgCheck(cp != NULL, "chCondWaitTimeoutS");
chDbgAssert(currp->p_mtxlist != NULL,
"chCondWaitTimeoutS(), #1",
"not owning a mutex");
mp = chMtxUnlockS(); /* unlocks the condvar mutex */
prio_insert(currp, &cp->c_queue); /* enters the condvar queue */
currp->p_wtcondp = cp; /* needed by the tracer */
chSchGoSleepTimeoutS(PRWTCOND, time); /* waits on the condvar */
msg = currp->p_rdymsg; /* fetches the wakeup message */
chMtxLockS(mp); /* atomically relocks the mutex */
return msg; /* returns the wakeup message */
}
#endif /* CH_USE_CONDVARS_TIMEOUT */
#endif /* CH_USE_CONDVARS && CH_USE_MUTEXES */
/** @} */
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
|