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/*
ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
This file is part of ChibiOS/RT and Copyright (C) 2008 Leon Woestenberg.
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/>.
*/
/**
* @addtogroup CondVars
* @{
*/
#include <ch.h>
#ifdef CH_USE_CONDVARS
/**
* Initializes s \p CondVar structure.
* @param cp pointer to a \p CondVar structure
*/
void chCondInit(CondVar *cp) {
fifo_init(&cp->c_queue);
}
/**
* Signals one thread that is waiting on the condition variable.
*
* @param mp pointer to the \p CondVar structure
*/
void chCondSignal(CondVar *cp) {
chSysLock();
chCondSignalS(cp);
chSysUnlock();
}
/**
* Signals one thread that is waiting on the condition variable.
*
* @param cp pointer to the \p CondVar structure
* @note This function must be called within a \p chSysLock() / \p chSysUnlock()
* block.
*/
void chCondSignalS(CondVar *cp) {
if (notempty(&cp->c_queue))
/* wake up the first thread, if any */
chSchWakeupS(fifo_remove(&cp->c_queue), RDY_OK);
}
/**
* Signal all threads that are waiting on the condition variable.
*
* @param mp pointer to the \p CondVar structure
*/
void chCondBroadcast(CondVar *cp) {
chSysLock();
chCondBroadcastS(cp);
chSchRescheduleS();
chSysUnlock();
}
/**
* Signal all threads that are waiting on the condition variable.
*
* @param cp pointer to the \p CondVar structure
* @note This function must be called within a \p chSysLock() / \p chSysUnlock()
*/
void chCondBroadcastS(CondVar *cp) {
/* 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;
}
/**
* Wait on the condition variable protected by the given mutex.
*
* Release the mutex, wait on the condition variable, and lock the mutex. This
* is done atomically.
*
* @param cp pointer to the \p CondVar structure
* @note This function must be called within a \p chSysLock() / \p chSysUnlock()
*/
msg_t chCondWait(CondVar *cp, Mutex *mp) {
msg_t msg;
chSysLock();
msg = chCondWaitS(cp, mp);
chSysUnlock();
return msg;
}
msg_t chCondWaitS(CondVar *cp, Mutex *mp) {
/* lock the mutex that protects access to the condition variable */
chMtxLockS(mp);
/* wait on the condition variable */
prio_insert(currp, &cp->c_queue);
/* Thread remembers the condition variable it waits on */
currp->p_wtcondp = cp;
/* sleep until signaled */
chSchGoSleepS(PRWTCOND);
/* lock the mutex that protects access to the condition variable */
chMtxLockS(mp);
currp->p_wtcondp = NULL;
return currp->p_rdymsg;
}
#endif /* CH_USE_CONDVARS */
/** @} */
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