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Diffstat (limited to 'os/kernel/include/chbsem.h')
| -rw-r--r-- | os/kernel/include/chbsem.h | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/os/kernel/include/chbsem.h b/os/kernel/include/chbsem.h new file mode 100644 index 000000000..856a3c3b3 --- /dev/null +++ b/os/kernel/include/chbsem.h @@ -0,0 +1,251 @@ +/*
+ ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
+ 2011,2012,2013 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 chbsem.h
+ * @brief Binary semaphores structures and macros.
+ *
+ * @addtogroup binary_semaphores
+ * @details Binary semaphores related APIs and services.
+ *
+ * <h2>Operation mode</h2>
+ * Binary semaphores are implemented as a set of macros that use the
+ * existing counting semaphores primitives. The difference between
+ * counting and binary semaphores is that the counter of binary
+ * semaphores is not allowed to grow above the value 1. Repeated
+ * signal operation are ignored. A binary semaphore can thus have
+ * only two defined states:
+ * - <b>Taken</b>, when its counter has a value of zero or lower
+ * than zero. A negative number represent the number of threads
+ * queued on the binary semaphore.
+ * - <b>Not taken</b>, when its counter has a value of one.
+ * .
+ * Binary semaphores are different from mutexes because there is no
+ * the concept of ownership, a binary semaphore can be taken by a
+ * thread and signaled by another thread or an interrupt handler,
+ * mutexes can only be taken and released by the same thread. Another
+ * difference is that binary semaphores, unlike mutexes, do not
+ * implement the priority inheritance protocol.<br>
+ * In order to use the binary semaphores APIs the @p CH_USE_SEMAPHORES
+ * option must be enabled in @p chconf.h.
+ * @{
+ */
+
+#ifndef _CHBSEM_H_
+#define _CHBSEM_H_
+
+#if CH_USE_SEMAPHORES || defined(__DOXYGEN__)
+
+/**
+ * @extends Semaphore
+ *
+ * @brief Binary semaphore type.
+ */
+typedef struct {
+ Semaphore bs_sem;
+} BinarySemaphore;
+
+/**
+ * @brief Data part of a static semaphore initializer.
+ * @details This macro should be used when statically initializing a semaphore
+ * that is part of a bigger structure.
+ *
+ * @param[in] name the name of the semaphore variable
+ * @param[in] taken the semaphore initial state
+ */
+#define _BSEMAPHORE_DATA(name, taken) \
+ {_SEMAPHORE_DATA(name.bs_sem, ((taken) ? 0 : 1))}
+
+/**
+ * @brief Static semaphore initializer.
+ * @details Statically initialized semaphores require no explicit
+ * initialization using @p chSemInit().
+ *
+ * @param[in] name the name of the semaphore variable
+ * @param[in] taken the semaphore initial state
+ */
+#define BSEMAPHORE_DECL(name, taken) \
+ BinarySemaphore name = _BSEMAPHORE_DATA(name, taken)
+
+/**
+ * @name Macro Functions
+ * @{
+ */
+/**
+ * @brief Initializes a binary semaphore.
+ *
+ * @param[out] bsp pointer to a @p BinarySemaphore structure
+ * @param[in] taken initial state of the binary semaphore:
+ * - @a FALSE, the initial state is not taken.
+ * - @a TRUE, the initial state is taken.
+ * .
+ *
+ * @init
+ */
+#define chBSemInit(bsp, taken) chSemInit(&(bsp)->bs_sem, (taken) ? 0 : 1)
+
+/**
+ * @brief Wait operation on the binary semaphore.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ * @return A message specifying how the invoking thread has been
+ * released from the semaphore.
+ * @retval RDY_OK if the binary semaphore has been successfully taken.
+ * @retval RDY_RESET if the binary semaphore has been reset using
+ * @p bsemReset().
+ *
+ * @api
+ */
+#define chBSemWait(bsp) chSemWait(&(bsp)->bs_sem)
+
+/**
+ * @brief Wait operation on the binary semaphore.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ * @return A message specifying how the invoking thread has been
+ * released from the semaphore.
+ * @retval RDY_OK if the binary semaphore has been successfully taken.
+ * @retval RDY_RESET if the binary semaphore has been reset using
+ * @p bsemReset().
+ *
+ * @sclass
+ */
+#define chBSemWaitS(bsp) chSemWaitS(&(bsp)->bs_sem)
+
+/**
+ * @brief Wait operation on the binary semaphore.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore 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 RDY_OK if the binary semaphore has been successfully taken.
+ * @retval RDY_RESET if the binary semaphore has been reset using
+ * @p bsemReset().
+ * @retval RDY_TIMEOUT if the binary semaphore has not been signaled or reset
+ * within the specified timeout.
+ *
+ * @api
+ */
+#define chBSemWaitTimeout(bsp, time) chSemWaitTimeout(&(bsp)->bs_sem, (time))
+
+/**
+ * @brief Wait operation on the binary semaphore.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore 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 RDY_OK if the binary semaphore has been successfully taken.
+ * @retval RDY_RESET if the binary semaphore has been reset using
+ * @p bsemReset().
+ * @retval RDY_TIMEOUT if the binary semaphore has not been signaled or reset
+ * within the specified timeout.
+ *
+ * @sclass
+ */
+#define chBSemWaitTimeoutS(bsp, time) chSemWaitTimeoutS(&(bsp)->bs_sem, (time))
+
+/**
+ * @brief Reset operation on the binary semaphore.
+ * @note The released threads can recognize they were waked up by a reset
+ * rather than a signal because the @p bsemWait() will return
+ * @p RDY_RESET instead of @p RDY_OK.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ * @param[in] taken new state of the binary semaphore
+ * - @a FALSE, the new state is not taken.
+ * - @a TRUE, the new state is taken.
+ * .
+ *
+ * @api
+ */
+#define chBSemReset(bsp, taken) chSemReset(&(bsp)->bs_sem, (taken) ? 0 : 1)
+
+/**
+ * @brief Reset operation on the binary semaphore.
+ * @note The released threads can recognize they were waked up by a reset
+ * rather than a signal because the @p bsemWait() will return
+ * @p RDY_RESET instead of @p RDY_OK.
+ * @note This function does not reschedule.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ * @param[in] taken new state of the binary semaphore
+ * - @a FALSE, the new state is not taken.
+ * - @a TRUE, the new state is taken.
+ * .
+ *
+ * @iclass
+ */
+#define chBSemResetI(bsp, taken) chSemResetI(&(bsp)->bs_sem, (taken) ? 0 : 1)
+
+/**
+ * @brief Performs a signal operation on a binary semaphore.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ *
+ * @api
+ */
+#define chBSemSignal(bsp) { \
+ chSysLock(); \
+ chBSemSignalI((bsp)); \
+ chSchRescheduleS(); \
+ chSysUnlock(); \
+}
+
+/**
+ * @brief Performs a signal operation on a binary semaphore.
+ * @note This function does not reschedule.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ *
+ * @iclass
+ */
+#define chBSemSignalI(bsp) { \
+ if ((bsp)->bs_sem.s_cnt < 1) \
+ chSemSignalI(&(bsp)->bs_sem); \
+}
+
+/**
+ * @brief Returns the binary semaphore current state.
+ *
+ * @param[in] bsp pointer to a @p BinarySemaphore structure
+ * @return The binary semaphore current state.
+ * @retval FALSE if the binary semaphore is not taken.
+ * @retval TRUE if the binary semaphore is taken.
+ *
+ * @iclass
+ */
+#define chBSemGetStateI(bsp) ((bsp)->bs_sem.s_cnt > 0 ? FALSE : TRUE)
+/** @} */
+
+#endif /* CH_USE_SEMAPHORES */
+
+#endif /* _CHBSEM_H_ */
+
+/** @} */
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