/* ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010, 2011,2012,2013 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 have been contributed by Leon Woestenberg. */ /** * @file chcond.c * @brief Condition Variables code. * * @addtogroup condvars Condition Variables * @details This module implements the Condition Variables mechanism. Condition * variables are an extensions to the Mutex subsystem and cannot * work alone. *

Operation mode

* The condition variable is a synchronization object meant to be * used inside a zone protected by a @p Mutex. Mutexes and CondVars * together can implement a Monitor construct. * @pre In order to use the condition variable APIs the @p CH_USE_CONDVARS * option must be enabled in @p chconf.h. * @{ */ #include "ch.h" #if (CH_USE_CONDVARS && CH_USE_MUTEXES) || defined(__DOXYGEN__) /** * @brief Initializes s @p CondVar structure. * * @param[out] cp pointer to a @p CondVar structure * * @init */ 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 * * @api */ void chCondSignal(CondVar *cp) { chDbgCheck(cp != NULL, "chCondSignal"); chSysLock(); if (notempty(&cp->c_queue)) chSchWakeupS(fifo_remove(&cp->c_queue), RDY_OK); chSysUnlock(); } /** * @brief Signals one thread that is waiting on the condition variable. * @post This function does not reschedule so a call to a rescheduling * function must be performed before unlocking the kernel. Note that * interrupt handlers always reschedule on exit so an explicit * reschedule must not be performed in ISRs. * * @param[in] cp pointer to the @p CondVar structure * * @iclass */ void chCondSignalI(CondVar *cp) { chDbgCheckClassI(); chDbgCheck(cp != NULL, "chCondSignalI"); if (notempty(&cp->c_queue)) chSchReadyI(fifo_remove(&cp->c_queue))->p_u.rdymsg = RDY_OK; } /** * @brief Signals all threads that are waiting on the condition variable. * * @param[in] cp pointer to the @p CondVar structure * * @api */ void chCondBroadcast(CondVar *cp) { chSysLock(); chCondBroadcastI(cp); chSchRescheduleS(); chSysUnlock(); } /** * @brief Signals all threads that are waiting on the condition variable. * @post This function does not reschedule so a call to a rescheduling * function must be performed before unlocking the kernel. Note that * interrupt handlers always reschedule on exit so an explicit * reschedule must not be performed in ISRs. * * @param[in] cp pointer to the @p CondVar structure * * @iclass */ void chCondBroadcastI(CondVar *cp) { chDbgCheckClassI(); 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_u.rdymsg = RDY_RESET; } /** * @brief Waits on the condition variable releasing the mutex lock. * @details Releases the currently owned mutex, waits on the condition * variable, and finally acquires the mutex again. All the sequence * is performed atomically. * @pre The invoking thread must have at least one owned mutex. * * @param[in] cp pointer to the @p CondVar structure * @return A message specifying how the invoking thread has been * released from the condition variable. * @retval RDY_OK if the condvar has been signaled using * @p chCondSignal(). * @retval RDY_RESET if the condvar has been signaled using * @p chCondBroadcast(). * * @api */ 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 currently owned mutex, waits on the condition * variable, and finally acquires the mutex again. All the sequence * is performed atomically. * @pre The invoking thread must have at least one owned mutex. * * @param[in] cp pointer to the @p CondVar structure * @return A message specifying how the invoking thread has been * released from the condition variable. * @retval RDY_OK if the condvar has been signaled using * @p chCondSignal(). * @retval RDY_RESET if the condvar has been signaled using * @p chCondBroadcast(). * * @sclass */ msg_t chCondWaitS(CondVar *cp) { Thread *ctp = currp; Mutex *mp; msg_t msg; chDbgCheckClassS(); chDbgCheck(cp != NULL, "chCondWaitS"); chDbgAssert(ctp->p_mtxlist != NULL, "chCondWaitS(), #1", "not owning a mutex"); mp = chMtxUnlockS(); ctp->p_u.wtobjp = cp; prio_insert(ctp, &cp->c_queue); chSchGoSleepS(THD_STATE_WTCOND); msg = ctp->p_u.rdymsg; chMtxLockS(mp); return msg; } #if CH_USE_CONDVARS_TIMEOUT || defined(__DOXYGEN__) /** * @brief Waits on the condition variable releasing the mutex lock. * @details Releases the currently owned mutex, waits on the condition * variable, and finally acquires the mutex again. All the sequence * is performed atomically. * @pre The invoking thread must have at least one owned mutex. * @pre The configuration option @p CH_USE_CONDVARS_TIMEOUT must be enabled * in order to use this function. * @post Exiting the function because a timeout does not re-acquire the * mutex, the mutex ownership is lost. * * @param[in] cp pointer to the @p CondVar structure * @param[in] time the number of ticks before the operation timeouts, the * special values are handled as follow: * - @a TIME_INFINITE no timeout. * - @a TIME_IMMEDIATE this value is not allowed. * . * @return A message specifying how the invoking thread has been * released from the condition variable. * @retval RDY_OK if the condvar has been signaled using * @p chCondSignal(). * @retval RDY_RESET if the condvar has been signaled using * @p chCondBroadcast(). * @retval RDY_TIMEOUT if the condvar has not been signaled within the * specified timeout. * * @api */ 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 currently owned mutex, waits on the condition * variable, and finally acquires the mutex again. All the sequence * is performed atomically. * @pre The invoking thread must have at least one owned mutex. * @pre The configuration option @p CH_USE_CONDVARS_TIMEOUT must be enabled * in order to use this function. * @post Exiting the function because a timeout does not re-acquire the * mutex, the mutex ownership is lost. * * @param[in] cp pointer to the @p CondVar structure * @param[in] time the number of ticks before the operation timeouts, the * special values are handled as follow: * - @a TIME_INFINITE no timeout. * - @a TIME_IMMEDIATE this value is not allowed. * . * @return A message specifying how the invoking thread has been * released from the condition variable. * @retval RDY_OK if the condvar has been signaled using * @p chCondSignal(). * @retval RDY_RESET if the condvar has been signaled using * @p chCondBroadcast(). * @retval RDY_TIMEOUT if the condvar has not been signaled within the * specified timeout. * * @sclass */ msg_t chCondWaitTimeoutS(CondVar *cp, systime_t time) { Mutex *mp; msg_t msg; chDbgCheckClassS(); chDbgCheck((cp != NULL) && (time != TIME_IMMEDIATE), "chCondWaitTimeoutS"); chDbgAssert(currp->p_mtxlist != NULL, "chCondWaitTimeoutS(), #1", "not owning a mutex"); mp = chMtxUnlockS(); currp->p_u.wtobjp = cp; prio_insert(currp, &cp->c_queue); msg = chSchGoSleepTimeoutS(THD_STATE_WTCOND, time); if (msg != RDY_TIMEOUT) chMtxLockS(mp); return msg; } #endif /* CH_USE_CONDVARS_TIMEOUT */ #endif /* CH_USE_CONDVARS && CH_USE_MUTEXES */ /** @} */ 8'>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