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/*
ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio.
This file is part of ChibiOS.
ChibiOS 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 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/>.
*/
/**
* @file nil/src/chsem.c
* @brief Nil RTOS semaphores source file.
*
* @addtogroup NIL_SEMAPHORES
* @{
*/
#include "ch.h"
#if (CH_CFG_USE_SEMAPHORES == TRUE) || defined(__DOXYGEN__)
/*===========================================================================*/
/* Module local definitions. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local functions. */
/*===========================================================================*/
/*===========================================================================*/
/* Module interrupt handlers. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Performs a wait operation on a semaphore with timeout specification.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] timeout 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 NIL_MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval NIL_MSG_RST if the semaphore has been reset using @p chSemReset().
* @retval NIL_MSG_TMO if the semaphore has not been signaled or reset within
* the specified timeout.
*
* @api
*/
msg_t chSemWaitTimeout(semaphore_t *sp, sysinterval_t timeout) {
msg_t msg;
chSysLock();
msg = chSemWaitTimeoutS(sp, timeout);
chSysUnlock();
return msg;
}
/**
* @brief Performs a wait operation on a semaphore with timeout specification.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] timeout 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 NIL_MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval NIL_MSG_RST if the semaphore has been reset using @p chSemReset().
* @retval NIL_MSG_TMO if the semaphore has not been signaled or reset within
* the specified timeout.
*
* @sclass
*/
msg_t chSemWaitTimeoutS(semaphore_t *sp, sysinterval_t timeout) {
chDbgCheckClassS();
chDbgCheck(sp != NULL);
/* Note, the semaphore counter is a volatile variable so accesses are
manually optimized.*/
cnt_t cnt = sp->cnt;
if (cnt <= (cnt_t)0) {
if (TIME_IMMEDIATE == timeout) {
return MSG_TIMEOUT;
}
sp->cnt = cnt - (cnt_t)1;
nil.current->u1.semp = sp;
return chSchGoSleepTimeoutS(NIL_STATE_WTQUEUE, timeout);
}
sp->cnt = cnt - (cnt_t)1;
return MSG_OK;
}
/**
* @brief Performs a signal operation on a semaphore.
*
* @param[in] sp pointer to a @p semaphore_t structure
*
* @api
*/
void chSemSignal(semaphore_t *sp) {
chSysLock();
chSemSignalI(sp);
chSchRescheduleS();
chSysUnlock();
}
/**
* @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);
if (++sp->cnt <= (cnt_t)0) {
thread_t *tp = nil_find_thread(NIL_STATE_WTQUEUE, (void *)sp);
chDbgAssert(tp != NULL, "thread not found");
(void) chSchReadyI(tp, MSG_OK);
}
}
/**
* @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.
*
* @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.
* @param[in] msg message to be sent
*
* @api
*/
void chSemResetWithMessage(semaphore_t *sp, cnt_t n, msg_t msg) {
chSysLock();
chSemResetWithMessageI(sp, n, msg);
chSchRescheduleS();
chSysUnlock();
}
/**
* @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.
*
* @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.
* @param[in] msg message to be sent
*
* @iclass
*/
void chSemResetWithMessageI(semaphore_t *sp, cnt_t n, msg_t msg) {
cnt_t cnt;
chDbgCheckClassI();
chDbgCheck((sp != NULL) && (n >= (cnt_t)0));
cnt = sp->cnt;
sp->cnt = n;
/* Does nothing for cnt >= 0, calling anyway.*/
(void) nil_ready_all((void *)sp, cnt, msg);
}
#endif /* CH_CFG_USE_SEMAPHORES == TRUE */
/** @} */
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