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Diffstat (limited to 'os/kernel/src/chsem.c')
| -rw-r--r-- | os/kernel/src/chsem.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/os/kernel/src/chsem.c b/os/kernel/src/chsem.c new file mode 100644 index 000000000..9a8570580 --- /dev/null +++ b/os/kernel/src/chsem.c @@ -0,0 +1,257 @@ +/*
+ ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
+
+ This file is part of ChibiOS/RT.
+
+ 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/>.
+*/
+
+/**
+ * @file chsem.c
+ * @brief Semaphores code.
+ * @addtogroup Semaphores
+ * @{
+ */
+
+#include <ch.h>
+
+#if CH_USE_SEMAPHORES
+
+#if CH_USE_SEMAPHORES_PRIORITY
+#define sem_insert(tp, qp) prio_insert(tp, qp)
+#else
+#define sem_insert(tp, qp) queue_insert(tp, qp)
+#endif
+
+/**
+ * @brief Initializes a semaphore with the specified counter value.
+ *
+ * @param[out] sp pointer to a @p Semaphore structure
+ * @param[in] n initial value of the semaphore counter. Must be non-negative.
+ * @note This function can be invoked from within an interrupt handler even if
+ * it is not an I-Class API because it does not touch any critical kernel
+ * data structure.
+ */
+void chSemInit(Semaphore *sp, cnt_t n) {
+
+ chDbgCheck((sp != NULL) && (n >= 0), "chSemInit");
+
+ queue_init(&sp->s_queue);
+ sp->s_cnt = n;
+}
+
+/**
+ * @brief Performs a reset operation on the semaphore.
+ *
+ * @param[in] sp pointer to a @p Semaphore structure
+ * @param[in] n the new value of the semaphore counter. The value must be non-negative.
+ * @note The released threads can recognize they were waked up by a reset
+ * instead than a signal because the @p chSemWait() will return
+ * @p RDY_RESET instead of @p RDY_OK.
+ */
+void chSemReset(Semaphore *sp, cnt_t n) {
+
+ chSysLock();
+ chSemResetI(sp, n);
+ chSchRescheduleS();
+ chSysUnlock();
+}
+
+/**
+ * @brief Performs a reset operation on the semaphore.
+ *
+ * @param[in] sp pointer to a @p Semaphore structure
+ * @param[in] n the new value of the semaphore counter. The value must be non-negative.
+ * @note The released threads can recognize they were waked up by a reset
+ * instead than a signal because the @p chSemWait() will return
+ * @p RDY_RESET instead of @p RDY_OK.
+ * @note This function does not reschedule.
+ */
+void chSemResetI(Semaphore *sp, cnt_t n) {
+ cnt_t cnt;
+
+ chDbgCheck((sp != NULL) && (n >= 0), "chSemResetI");
+
+ cnt = sp->s_cnt;
+ sp->s_cnt = n;
+ while (cnt++ < 0)
+ chSchReadyI(lifo_remove(&sp->s_queue))->p_rdymsg = RDY_RESET;
+}
+
+/**
+ * @brief Performs a wait operation on a semaphore.
+ *
+ * @param[in] sp pointer to a @p Semaphore structure
+ * @retval RDY_OK if the semaphore was signaled or not taken.
+ * @retval RDY_RESET if the semaphore was reset using @p chSemReset().
+ */
+msg_t chSemWait(Semaphore *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 structure
+ * @retval RDY_OK if the semaphore was signaled or not taken.
+ * @retval RDY_RESET if the semaphore was reset using @p chSemReset().
+ * @note This function must be called with interrupts disabled.
+ * @note This function cannot be called by an interrupt handler.
+ */
+msg_t chSemWaitS(Semaphore *sp) {
+
+ chDbgCheck(sp != NULL, "chSemWaitS");
+
+ if (--sp->s_cnt < 0) {
+ sem_insert(currp, &sp->s_queue);
+ currp->p_wtsemp = sp;
+ chSchGoSleepS(PRWTSEM);
+ return currp->p_rdymsg;
+ }
+ return RDY_OK;
+}
+
+/**
+ * @brief Performs a wait operation on a semaphore with timeout specification.
+ *
+ * @param[in] sp pointer to a @p Semaphore 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.
+ * .
+ * @retval RDY_OK if the semaphore was signaled or not taken.
+ * @retval RDY_RESET if the semaphore was reset using @p chSemReset().
+ * @retval RDY_TIMEOUT if the semaphore was not signaled or reset within the
+ * specified timeout.
+ */
+msg_t chSemWaitTimeout(Semaphore *sp, systime_t time) {
+ msg_t msg;
+
+ chSysLock();
+ msg = chSemWaitTimeoutS(sp, time);
+ chSysUnlock();
+ return msg;
+}
+
+/**
+ * @brief Performs a wait operation on a semaphore with timeout specification.
+ *
+ * @param[in] sp pointer to a @p Semaphore 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.
+ * .
+ * @retval RDY_OK if the semaphore was signaled or not taken.
+ * @retval RDY_RESET if the semaphore was reset using @p chSemReset().
+ * @retval RDY_TIMEOUT if the semaphore was not signaled or reset within the specified
+ * timeout.
+ */
+msg_t chSemWaitTimeoutS(Semaphore *sp, systime_t time) {
+
+ chDbgCheck(sp != NULL, "chSemWaitTimeoutS");
+
+ if (--sp->s_cnt < 0) {
+ if (TIME_IMMEDIATE == time) {
+ sp->s_cnt++;
+ return RDY_TIMEOUT;
+ }
+ sem_insert(currp, &sp->s_queue);
+ currp->p_wtsemp = sp;
+ return chSchGoSleepTimeoutS(PRWTSEM, time);
+ }
+ return RDY_OK;
+}
+
+/**
+ * @brief Performs a signal operation on a semaphore.
+ *
+ * @param[in] sp pointer to a @p Semaphore structure
+ * @note The function is available only if the @p CH_USE_SEMAPHORES
+ * option is enabled in @p chconf.h.
+ */
+void chSemSignal(Semaphore *sp) {
+
+ chDbgCheck(sp != NULL, "chSemSignal");
+
+ chSysLock();
+ if (sp->s_cnt++ < 0)
+ chSchWakeupS(fifo_remove(&sp->s_queue), RDY_OK);
+ chSysUnlock();
+}
+
+/**
+ * @brief Performs a signal operation on a semaphore.
+ *
+ * @param[in] sp pointer to a @p Semaphore structure
+ * @note The function is available only if the @p CH_USE_SEMAPHORES
+ * option is enabled in @p chconf.h.
+ * @note This function does not reschedule.
+ */
+void chSemSignalI(Semaphore *sp) {
+
+ chDbgCheck(sp != NULL, "chSemSignalI");
+
+ if (sp->s_cnt++ < 0) {
+ /* NOTE: It is done this way in order to allow a tail call on
+ chSchReadyI().*/
+ Thread *tp = fifo_remove(&sp->s_queue);
+ tp->p_rdymsg = RDY_OK;
+ chSchReadyI(tp);
+ }
+}
+
+#if CH_USE_SEMSW
+/**
+ * @brief Performs atomic signal and wait operations on two semaphores.
+ *
+ * @param[in] sps pointer to a @p Semaphore structure to be signaled
+ * @param[in] spw pointer to a @p Semaphore structure to be wait on
+ * @retval RDY_OK if the semaphore was signaled or not taken.
+ * @retval RDY_RESET if the semaphore was reset using @p chSemReset().
+ * @note The function is available only if the @p CH_USE_SEMSW
+ * option is enabled in @p chconf.h.
+ */
+msg_t chSemSignalWait(Semaphore *sps, Semaphore *spw) {
+ msg_t msg;
+
+ chDbgCheck((sps != NULL) && (spw != NULL), "chSemSignalWait");
+
+ chSysLock();
+ if (sps->s_cnt++ < 0)
+ chSchReadyI(fifo_remove(&sps->s_queue))->p_rdymsg = RDY_OK;
+ if (--spw->s_cnt < 0) {
+ sem_insert(currp, &spw->s_queue);
+ currp->p_wtsemp = spw;
+ chSchGoSleepS(PRWTSEM);
+ msg = currp->p_rdymsg;
+ }
+ else {
+ chSchRescheduleS();
+ msg = RDY_OK;
+ }
+ chSysUnlock();
+ return msg;
+}
+#endif /* CH_USE_SEMSW */
+
+#endif /* CH_USE_SEMAPHORES */
+
+/** @} */
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