From 48026bb824fd2d9cfb00ecd040db6ef3a416bae9 Mon Sep 17 00:00:00 2001 From: Clyne Sullivan Date: Fri, 22 Jan 2021 21:43:36 -0500 Subject: upload initial port --- ChibiOS_20.3.2/os/rt/src/chsem.c | 405 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 405 insertions(+) create mode 100644 ChibiOS_20.3.2/os/rt/src/chsem.c (limited to 'ChibiOS_20.3.2/os/rt/src/chsem.c') diff --git a/ChibiOS_20.3.2/os/rt/src/chsem.c b/ChibiOS_20.3.2/os/rt/src/chsem.c new file mode 100644 index 0000000..7671aec --- /dev/null +++ b/ChibiOS_20.3.2/os/rt/src/chsem.c @@ -0,0 +1,405 @@ +/* + 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 . +*/ + +/** + * @file rt/src/chsem.c + * @brief Semaphores code. + * + * @addtogroup semaphores + * @details Semaphores related APIs and services. + *

Operation mode

+ * Semaphores are a flexible synchronization primitive, ChibiOS/RT + * implements semaphores in their "counting semaphores" variant as + * defined by Edsger Dijkstra plus several enhancements like: + * - Wait operation with timeout. + * - Reset operation. + * - Atomic wait+signal operation. + * - Return message from the wait operation (OK, RESET, TIMEOUT). + * . + * The binary semaphores variant can be easily implemented using + * counting semaphores.
+ * Operations defined for semaphores: + * - Signal: The semaphore counter is increased and if the + * result is non-positive then a waiting thread is removed from + * the semaphore queue and made ready for execution. + * - Wait: The semaphore counter is decreased and if the result + * becomes negative the thread is queued in the semaphore and + * suspended. + * - Reset: The semaphore counter is reset to a non-negative + * value and all the threads in the queue are released. + * . + * Semaphores can be used as guards for mutual exclusion zones + * (note that mutexes are recommended for this kind of use) but + * also have other uses, queues guards and counters for example.
+ * Semaphores usually use a FIFO queuing strategy but it is possible + * to make them order threads by priority by enabling + * @p CH_CFG_USE_SEMAPHORES_PRIORITY in @p chconf.h. + * @pre In order to use the semaphore APIs the @p CH_CFG_USE_SEMAPHORES + * option must be enabled in @p chconf.h. + * @{ + */ + +#include "ch.h" + +#if (CH_CFG_USE_SEMAPHORES == TRUE) || defined(__DOXYGEN__) + +/*===========================================================================*/ +/* Module exported variables. */ +/*===========================================================================*/ + +/*===========================================================================*/ +/* Module local types. */ +/*===========================================================================*/ + +/*===========================================================================*/ +/* Module local variables. */ +/*===========================================================================*/ + +/*===========================================================================*/ +/* Module local functions. */ +/*===========================================================================*/ + +#if CH_CFG_USE_SEMAPHORES_PRIORITY == TRUE +#define sem_insert(tp, qp) queue_prio_insert(tp, qp) +#else +#define sem_insert(tp, qp) queue_insert(tp, qp) +#endif + +/*===========================================================================*/ +/* Module exported functions. */ +/*===========================================================================*/ + +/** + * @brief Initializes a semaphore with the specified counter value. + * + * @param[out] sp pointer to a @p semaphore_t structure + * @param[in] n initial value of the semaphore counter. Must be + * non-negative. + * + * @init + */ +void chSemObjectInit(semaphore_t *sp, cnt_t n) { + + chDbgCheck((sp != NULL) && (n >= (cnt_t)0)); + + queue_init(&sp->queue); + sp->cnt = 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. + * + * @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) { + + chDbgCheckClassI(); + chDbgCheck((sp != NULL) && (n >= (cnt_t)0)); + chDbgAssert(((sp->cnt >= (cnt_t)0) && queue_isempty(&sp->queue)) || + ((sp->cnt < (cnt_t)0) && queue_notempty(&sp->queue)), + "inconsistent semaphore"); + + sp->cnt = n; + while (queue_notempty(&sp->queue)) { + chSchReadyI(queue_lifo_remove(&sp->queue))->u.rdymsg = msg; + } +} + +/** + * @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(). + * + * @api + */ +msg_t chSemWait(semaphore_t *sp) { + msg_t msg; + + chSysLock(); + msg = chSemWaitS(sp); + chSysUnlock(); + + return msg; +} + +/** + * @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->cnt >= (cnt_t)0) && queue_isempty(&sp->queue)) || + ((sp->cnt < (cnt_t)0) && queue_notempty(&sp->queue)), + "inconsistent semaphore"); + + if (--sp->cnt < (cnt_t)0) { + currp->u.wtsemp = sp; + sem_insert(currp, &sp->queue); + chSchGoSleepS(CH_STATE_WTSEM); + + return currp->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] 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 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. + * + * @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 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, sysinterval_t timeout) { + + chDbgCheckClassS(); + chDbgCheck(sp != NULL); + chDbgAssert(((sp->cnt >= (cnt_t)0) && queue_isempty(&sp->queue)) || + ((sp->cnt < (cnt_t)0) && queue_notempty(&sp->queue)), + "inconsistent semaphore"); + + if (--sp->cnt < (cnt_t)0) { + if (TIME_IMMEDIATE == timeout) { + sp->cnt++; + + return MSG_TIMEOUT; + } + currp->u.wtsemp = sp; + sem_insert(currp, &sp->queue); + + return chSchGoSleepTimeoutS(CH_STATE_WTSEM, timeout); + } + + 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) { + + chDbgCheck(sp != NULL); + + chSysLock(); + chDbgAssert(((sp->cnt >= (cnt_t)0) && queue_isempty(&sp->queue)) || + ((sp->cnt < (cnt_t)0) && queue_notempty(&sp->queue)), + "inconsistent semaphore"); + if (++sp->cnt <= (cnt_t)0) { + chSchWakeupS(queue_fifo_remove(&sp->queue), MSG_OK); + } + 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); + chDbgAssert(((sp->cnt >= (cnt_t)0) && queue_isempty(&sp->queue)) || + ((sp->cnt < (cnt_t)0) && queue_notempty(&sp->queue)), + "inconsistent semaphore"); + + if (++sp->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->queue); + tp->u.rdymsg = MSG_OK; + (void) chSchReadyI(tp); + } +} + +/** + * @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 > (cnt_t)0)); + chDbgAssert(((sp->cnt >= (cnt_t)0) && queue_isempty(&sp->queue)) || + ((sp->cnt < (cnt_t)0) && queue_notempty(&sp->queue)), + "inconsistent semaphore"); + + while (n > (cnt_t)0) { + if (++sp->cnt <= (cnt_t)0) { + chSchReadyI(queue_fifo_remove(&sp->queue))->u.rdymsg = MSG_OK; + } + n--; + } +} + +/** + * @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)); + + chSysLock(); + chDbgAssert(((sps->cnt >= (cnt_t)0) && queue_isempty(&sps->queue)) || + ((sps->cnt < (cnt_t)0) && queue_notempty(&sps->queue)), + "inconsistent semaphore"); + chDbgAssert(((spw->cnt >= (cnt_t)0) && queue_isempty(&spw->queue)) || + ((spw->cnt < (cnt_t)0) && queue_notempty(&spw->queue)), + "inconsistent semaphore"); + if (++sps->cnt <= (cnt_t)0) { + chSchReadyI(queue_fifo_remove(&sps->queue))->u.rdymsg = MSG_OK; + } + if (--spw->cnt < (cnt_t)0) { + thread_t *ctp = currp; + sem_insert(ctp, &spw->queue); + ctp->u.wtsemp = spw; + chSchGoSleepS(CH_STATE_WTSEM); + msg = ctp->u.rdymsg; + } + else { + chSchRescheduleS(); + msg = MSG_OK; + } + chSysUnlock(); + + return msg; +} + +#endif /* CH_CFG_USE_SEMAPHORES == TRUE */ + +/** @} */ -- cgit v1.2.3