225 lines
7.9 KiB
C
225 lines
7.9 KiB
C
/*
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ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio.
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This file is part of ChibiOS.
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ChibiOS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file nil/src/chsem.c
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* @brief Nil RTOS semaphores source file.
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*
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* @addtogroup NIL_SEMAPHORES
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* @{
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*/
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#include "ch.h"
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#if (CH_CFG_USE_SEMAPHORES == TRUE) || defined(__DOXYGEN__)
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/*===========================================================================*/
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/* Module local definitions. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module exported variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local functions. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module interrupt handlers. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module exported functions. */
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/*===========================================================================*/
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/**
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* @brief Performs a wait operation on a semaphore with timeout specification.
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*
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* @param[in] sp pointer to a @p semaphore_t structure
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* @param[in] timeout the number of ticks before the operation timeouts,
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* the following special values are allowed:
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* - @a TIME_IMMEDIATE immediate timeout.
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* - @a TIME_INFINITE no timeout.
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* .
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* @return A message specifying how the invoking thread has been
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* released from the semaphore.
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* @retval NIL_MSG_OK if the thread has not stopped on the semaphore or the
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* semaphore has been signaled.
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* @retval NIL_MSG_RST if the semaphore has been reset using @p chSemReset().
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* @retval NIL_MSG_TMO if the semaphore has not been signaled or reset within
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* the specified timeout.
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*
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* @api
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*/
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msg_t chSemWaitTimeout(semaphore_t *sp, sysinterval_t timeout) {
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msg_t msg;
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chSysLock();
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msg = chSemWaitTimeoutS(sp, timeout);
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chSysUnlock();
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return msg;
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}
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/**
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* @brief Performs a wait operation on a semaphore with timeout specification.
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*
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* @param[in] sp pointer to a @p semaphore_t structure
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* @param[in] timeout the number of ticks before the operation timeouts,
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* the following special values are allowed:
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* - @a TIME_IMMEDIATE immediate timeout.
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* - @a TIME_INFINITE no timeout.
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* .
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* @return A message specifying how the invoking thread has been
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* released from the semaphore.
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* @retval NIL_MSG_OK if the thread has not stopped on the semaphore or the
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* semaphore has been signaled.
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* @retval NIL_MSG_RST if the semaphore has been reset using @p chSemReset().
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* @retval NIL_MSG_TMO if the semaphore has not been signaled or reset within
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* the specified timeout.
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*
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* @sclass
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*/
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msg_t chSemWaitTimeoutS(semaphore_t *sp, sysinterval_t timeout) {
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chDbgCheckClassS();
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chDbgCheck(sp != NULL);
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/* Note, the semaphore counter is a volatile variable so accesses are
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manually optimized.*/
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cnt_t cnt = sp->cnt;
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if (cnt <= (cnt_t)0) {
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if (TIME_IMMEDIATE == timeout) {
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return MSG_TIMEOUT;
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}
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sp->cnt = cnt - (cnt_t)1;
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nil.current->u1.semp = sp;
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return chSchGoSleepTimeoutS(NIL_STATE_WTQUEUE, timeout);
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}
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sp->cnt = cnt - (cnt_t)1;
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return MSG_OK;
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}
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/**
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* @brief Performs a signal operation on a semaphore.
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*
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* @param[in] sp pointer to a @p semaphore_t structure
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*
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* @api
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*/
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void chSemSignal(semaphore_t *sp) {
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chSysLock();
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chSemSignalI(sp);
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chSchRescheduleS();
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chSysUnlock();
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}
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/**
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* @brief Performs a signal operation on a semaphore.
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* @post This function does not reschedule so a call to a rescheduling
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* function must be performed before unlocking the kernel. Note that
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* interrupt handlers always reschedule on exit so an explicit
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* reschedule must not be performed in ISRs.
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*
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* @param[in] sp pointer to a @p semaphore_t structure
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*
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* @iclass
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*/
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void chSemSignalI(semaphore_t *sp) {
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chDbgCheckClassI();
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chDbgCheck(sp != NULL);
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if (++sp->cnt <= (cnt_t)0) {
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thread_t *tp = nil_find_thread(NIL_STATE_WTQUEUE, (void *)sp);
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chDbgAssert(tp != NULL, "thread not found");
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(void) chSchReadyI(tp, MSG_OK);
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}
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}
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/**
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* @brief Performs a reset operation on the semaphore.
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* @post After invoking this function all the threads waiting on the
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* semaphore, if any, are released and the semaphore counter is set
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* to the specified, non negative, value.
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* @post This function does not reschedule so a call to a rescheduling
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* function must be performed before unlocking the kernel. Note that
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* interrupt handlers always reschedule on exit so an explicit
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* reschedule must not be performed in ISRs.
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*
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* @param[in] sp pointer to a @p semaphore_t structure
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* @param[in] n the new value of the semaphore counter. The value must
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* be non-negative.
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* @param[in] msg message to be sent
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*
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* @api
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*/
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void chSemResetWithMessage(semaphore_t *sp, cnt_t n, msg_t msg) {
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chSysLock();
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chSemResetWithMessageI(sp, n, msg);
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chSchRescheduleS();
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chSysUnlock();
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}
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/**
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* @brief Performs a reset operation on the semaphore.
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* @post After invoking this function all the threads waiting on the
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* semaphore, if any, are released and the semaphore counter is set
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* to the specified, non negative, value.
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* @post This function does not reschedule so a call to a rescheduling
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* function must be performed before unlocking the kernel. Note that
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* interrupt handlers always reschedule on exit so an explicit
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* reschedule must not be performed in ISRs.
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*
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* @param[in] sp pointer to a @p semaphore_t structure
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* @param[in] n the new value of the semaphore counter. The value must
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* be non-negative.
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* @param[in] msg message to be sent
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*
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* @iclass
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*/
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void chSemResetWithMessageI(semaphore_t *sp, cnt_t n, msg_t msg) {
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cnt_t cnt;
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chDbgCheckClassI();
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chDbgCheck((sp != NULL) && (n >= (cnt_t)0));
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cnt = sp->cnt;
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sp->cnt = n;
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/* Does nothing for cnt >= 0, calling anyway.*/
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(void) nil_ready_all((void *)sp, cnt, msg);
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}
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#endif /* CH_CFG_USE_SEMAPHORES == TRUE */
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/** @} */
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