/**
* @brief Performs atomic signal and wait operations on two semaphores.
*
* @param[in] sps pointer to a @p semaphore_t structure to be signaled
* @param[in] spw pointer to a @p semaphore_t structure to wait on
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval MSG_RESET if the semaphore has been reset using @p chSemReset().
*
* @api
*/
msg_t chSemSignalWait(semaphore_t *sps, semaphore_t *spw) {
msg_t msg;
chDbgCheck((sps != NULL) && (spw != NULL));
chDbgAssert(((sps->s_cnt >= (cnt_t)0) && queue_isempty(&sps->s_queue)) ||
((sps->s_cnt < (cnt_t)0) && queue_notempty(&sps->s_queue)),
"inconsistent semaphore");
chDbgAssert(((spw->s_cnt >= (cnt_t)0) && queue_isempty(&spw->s_queue)) ||
((spw->s_cnt < (cnt_t)0) && queue_notempty(&spw->s_queue)),
"inconsistent semaphore");
chSysLock();
if (++sps->s_cnt <= (cnt_t)0) {
chSchReadyI(queue_fifo_remove(&sps->s_queue))->p_u.rdymsg = MSG_OK;
}
if (--spw->s_cnt < (cnt_t)0) {
thread_t *ctp = currp;
sem_insert(ctp, &spw->s_queue);
ctp->p_u.wtsemp = spw;
chSchGoSleepS(CH_STATE_WTSEM);
msg = ctp->p_u.rdymsg;
}
else {
chSchRescheduleS();
msg = MSG_OK;
}
chSysUnlock();
return msg;
}
/**
* @brief Signals one thread that is waiting on the condition variable.
*
* @param[in] cp pointer to the @p condition_variable_t structure
*
* @api
*/
void chCondSignal(condition_variable_t *cp) {
chDbgCheck(cp != NULL);
chSysLock();
if (queue_notempty(&cp->c_queue))
chSchWakeupS(queue_fifo_remove(&cp->c_queue), MSG_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 condition_variable_t structure
*
* @iclass
*/
void chCondSignalI(condition_variable_t *cp) {
chDbgCheckClassI();
chDbgCheck(cp != NULL);
if (queue_notempty(&cp->c_queue)) {
thread_t *tp = queue_fifo_remove(&cp->c_queue);
tp->p_u.rdymsg = MSG_OK;
chSchReadyI(tp);
}
}
/**
* @brief Performs a signal operation on a semaphore.
*
* @param[in] sp pointer to a @p semaphore_t structure
*
* @api
*/
void chSemSignal(semaphore_t *sp) {
chDbgCheck(sp != NULL);
chDbgAssert(((sp->s_cnt >= 0) && queue_isempty(&sp->s_queue)) ||
((sp->s_cnt < 0) && queue_notempty(&sp->s_queue)),
"inconsistent semaphore");
chSysLock();
if (++sp->s_cnt <= 0)
chSchWakeupS(queue_fifo_remove(&sp->s_queue), MSG_OK);
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 condition_variable_t structure
*
* @iclass
*/
void chCondBroadcastI(condition_variable_t *cp) {
chDbgCheckClassI();
chDbgCheck(cp != NULL);
/* Empties the condition variable queue and inserts all the threads into the
ready list in FIFO order. The wakeup message is set to @p MSG_RESET in
order to make a chCondBroadcast() detectable from a chCondSignal().*/
while (queue_notempty(&cp->queue)) {
chSchReadyI(queue_fifo_remove(&cp->queue))->u.rdymsg = MSG_RESET;
}
}
/**
* @brief Adds the specified value to the semaphore counter.
* @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] sp pointer to a @p semaphore_t structure
* @param[in] n value to be added to the semaphore counter. The value
* must be positive.
*
* @iclass
*/
void chSemAddCounterI(semaphore_t *sp, cnt_t n) {
chDbgCheckClassI();
chDbgCheck((sp != NULL) && (n > 0));
chDbgAssert(((sp->s_cnt >= 0) && queue_isempty(&sp->s_queue)) ||
((sp->s_cnt < 0) && queue_notempty(&sp->s_queue)),
"inconsistent semaphore");
while (n > 0) {
if (++sp->s_cnt <= 0)
chSchReadyI(queue_fifo_remove(&sp->s_queue))->p_u.rdymsg = MSG_OK;
n--;
}
}
/**
* @brief Performs a reset operation on the semaphore.
* @post After invoking this function all the threads waiting on the
* semaphore, if any, are released and the semaphore counter is set
* to the specified, non negative, value.
* @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.
* @note The released threads can recognize they were waked up by a reset
* rather than a signal because the @p chSemWait() will return
* @p MSG_RESET instead of @p MSG_OK.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] n the new value of the semaphore counter. The value must
* be non-negative.
*
* @iclass
*/
void chSemResetI(semaphore_t *sp, cnt_t n) {
cnt_t cnt;
chDbgCheckClassI();
chDbgCheck((sp != NULL) && (n >= 0));
chDbgAssert(((sp->s_cnt >= 0) && queue_isempty(&sp->s_queue)) ||
((sp->s_cnt < 0) && queue_notempty(&sp->s_queue)),
"inconsistent semaphore");
cnt = sp->s_cnt;
sp->s_cnt = n;
while (++cnt <= 0)
chSchReadyI(queue_lifo_remove(&sp->s_queue))->p_u.rdymsg = MSG_RESET;
}
/**
* @brief Performs a signal operation on a semaphore.
* @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] sp pointer to a @p semaphore_t structure
*
* @iclass
*/
void chSemSignalI(semaphore_t *sp) {
chDbgCheckClassI();
chDbgCheck(sp != NULL);
chDbgAssert(((sp->s_cnt >= (cnt_t)0) && queue_isempty(&sp->s_queue)) ||
((sp->s_cnt < (cnt_t)0) && queue_notempty(&sp->s_queue)),
"inconsistent semaphore");
if (++sp->s_cnt <= (cnt_t)0) {
/* Note, it is done this way in order to allow a tail call on
chSchReadyI().*/
thread_t *tp = queue_fifo_remove(&sp->s_queue);
tp->p_u.rdymsg = MSG_OK;
(void) chSchReadyI(tp);
}
}
/**
* @brief Performs a wait operation on a semaphore.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval MSG_RESET if the semaphore has been reset using @p chSemReset().
*
* @sclass
*/
msg_t chSemWaitS(semaphore_t *sp) {
chDbgCheckClassS();
chDbgCheck(sp != NULL);
chDbgAssert(((sp->s_cnt >= 0) && queue_isempty(&sp->s_queue)) ||
((sp->s_cnt < 0) && queue_notempty(&sp->s_queue)),
"inconsistent semaphore");
if (--sp->s_cnt < 0) {
currp->p_u.wtobjp = sp;
sem_insert(currp, &sp->s_queue);
chSchGoSleepS(CH_STATE_WTSEM);
return currp->p_u.rdymsg;
}
return MSG_OK;
}
/**
* @brief Performs a wait operation on a semaphore with timeout specification.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval MSG_RESET if the semaphore has been reset using @p chSemReset().
* @retval MSG_TIMEOUT if the semaphore has not been signaled or reset within
* the specified timeout.
*
* @sclass
*/
msg_t chSemWaitTimeoutS(semaphore_t *sp, systime_t time) {
chDbgCheckClassS();
chDbgCheck(sp != NULL);
chDbgAssert(((sp->s_cnt >= 0) && queue_isempty(&sp->s_queue)) ||
((sp->s_cnt < 0) && queue_notempty(&sp->s_queue)),
"inconsistent semaphore");
if (--sp->s_cnt < 0) {
if (TIME_IMMEDIATE == time) {
sp->s_cnt++;
return MSG_TIMEOUT;
}
currp->p_u.wtobjp = sp;
sem_insert(currp, &sp->s_queue);
return chSchGoSleepTimeoutS(CH_STATE_WTSEM, time);
}
return MSG_OK;
}
/**
* @brief Dequeues and wakes up all threads from the threads queue object.
*
* @param[in] tqp pointer to the threads queue object
* @param[in] msg the message code
*
* @iclass
*/
void chThdDequeueAllI(threads_queue_t *tqp, msg_t msg) {
while (queue_notempty(tqp)) {
chThdDoDequeueNextI(tqp, msg);
}
}
/**
* @brief Dequeues and wakes up one thread from the threads queue object,
* if any.
*
* @param[in] tqp pointer to the threads queue object
* @param[in] msg the message code
*
* @iclass
*/
void chThdDequeueNextI(threads_queue_t *tqp, msg_t msg) {
if (queue_notempty(tqp))
chThdDoDequeueNextI(tqp, msg);
}