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Diffstat (limited to 'os/kernel/src/chcond.c')
| -rw-r--r-- | os/kernel/src/chcond.c | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/os/kernel/src/chcond.c b/os/kernel/src/chcond.c new file mode 100644 index 000000000..c217bf6fd --- /dev/null +++ b/os/kernel/src/chcond.c @@ -0,0 +1,285 @@ +/*
+ 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 <http://www.gnu.org/licenses/>.
+*/
+/*
+ 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.
+ * <h2>Operation mode</h2>
+ * 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 <b>must</b> 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 <b>must</b> 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 <b>must</b> 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 <b>must</b> 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 */
+
+/** @} */
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