312 lines
11 KiB
C
312 lines
11 KiB
C
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/*
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ChibiOS - Copyright (C) 2006..2016 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 chbsem.h
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* @brief Binary semaphores structures and macros.
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*
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* @addtogroup binary_semaphores
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* @details Binary semaphores related APIs and services.
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* <h2>Operation mode</h2>
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* Binary semaphores are implemented as a set of inline functions
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* that use the existing counting semaphores primitives. The
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* difference between counting and binary semaphores is that the
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* counter of binary semaphores is not allowed to grow above the
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* value 1. Repeated signal operation are ignored. A binary
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* semaphore can thus have only two defined states:
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* - <b>Taken</b>, when its counter has a value of zero or lower
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* than zero. A negative number represent the number of threads
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* queued on the binary semaphore.
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* - <b>Not taken</b>, when its counter has a value of one.
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* .
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* Binary semaphores are different from mutexes because there is no
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* concept of ownership, a binary semaphore can be taken by a
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* thread and signaled by another thread or an interrupt handler,
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* mutexes can only be taken and released by the same thread. Another
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* difference is that binary semaphores, unlike mutexes, do not
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* implement the priority inheritance protocol.<br>
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* In order to use the binary semaphores APIs the
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* @p CH_CFG_USE_SEMAPHORES option must be enabled in @p chconf.h.
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* @{
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*/
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#ifndef CHBSEM_H
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#define CHBSEM_H
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#if (CH_CFG_USE_SEMAPHORES == TRUE) || defined(__DOXYGEN__)
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/*===========================================================================*/
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/* Module constants. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module pre-compile time settings. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Derived constants and error checks. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module data structures and types. */
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/*===========================================================================*/
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/**
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* @extends semaphore_t
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*
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* @brief Binary semaphore type.
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*/
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typedef struct {
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semaphore_t sem;
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} binary_semaphore_t;
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/*===========================================================================*/
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/* Module macros. */
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/*===========================================================================*/
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/**
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* @brief Data part of a static semaphore initializer.
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* @details This macro should be used when statically initializing a semaphore
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* that is part of a bigger structure.
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*
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* @param[in] name the name of the semaphore variable
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* @param[in] taken the semaphore initial state
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*/
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#define _BSEMAPHORE_DATA(name, taken) \
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{_SEMAPHORE_DATA(name.sem, ((taken) ? 0 : 1))}
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/**
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* @brief Static semaphore initializer.
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* @details Statically initialized semaphores require no explicit
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* initialization using @p chBSemInit().
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*
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* @param[in] name the name of the semaphore variable
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* @param[in] taken the semaphore initial state
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*/
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#define BSEMAPHORE_DECL(name, taken) \
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binary_semaphore_t name = _BSEMAPHORE_DATA(name, taken)
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/*===========================================================================*/
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/* External declarations. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module inline functions. */
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/*===========================================================================*/
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/**
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* @brief Initializes a binary semaphore.
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*
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* @param[out] bsp pointer to a @p binary_semaphore_t structure
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* @param[in] taken initial state of the binary semaphore:
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* - @a false, the initial state is not taken.
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* - @a true, the initial state is taken.
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* .
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*
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* @init
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*/
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static inline void chBSemObjectInit(binary_semaphore_t *bsp, bool taken) {
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chSemObjectInit(&bsp->sem, taken ? (cnt_t)0 : (cnt_t)1);
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}
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/**
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* @brief Wait operation on the binary semaphore.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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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 MSG_OK if the binary semaphore has been successfully taken.
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* @retval MSG_RESET if the binary semaphore has been reset using
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* @p bsemReset().
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*
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* @api
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*/
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static inline msg_t chBSemWait(binary_semaphore_t *bsp) {
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return chSemWait(&bsp->sem);
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}
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/**
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* @brief Wait operation on the binary semaphore.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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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 MSG_OK if the binary semaphore has been successfully taken.
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* @retval MSG_RESET if the binary semaphore has been reset using
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* @p bsemReset().
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*
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* @sclass
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*/
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static inline msg_t chBSemWaitS(binary_semaphore_t *bsp) {
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chDbgCheckClassS();
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return chSemWaitS(&bsp->sem);
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}
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/**
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* @brief Wait operation on the binary semaphore.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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* @param[in] time 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 MSG_OK if the binary semaphore has been successfully taken.
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* @retval MSG_RESET if the binary semaphore has been reset using
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* @p bsemReset().
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* @retval MSG_TIMEOUT if the binary semaphore has not been signaled or reset
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* within the specified timeout.
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*
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* @sclass
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*/
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static inline msg_t chBSemWaitTimeoutS(binary_semaphore_t *bsp,
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systime_t time) {
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chDbgCheckClassS();
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return chSemWaitTimeoutS(&bsp->sem, time);
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}
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/**
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* @brief Wait operation on the binary semaphore.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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* @param[in] time 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 MSG_OK if the binary semaphore has been successfully taken.
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* @retval MSG_RESET if the binary semaphore has been reset using
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* @p bsemReset().
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* @retval MSG_TIMEOUT if the binary semaphore has not been signaled or reset
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* within the specified timeout.
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*
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* @api
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*/
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static inline msg_t chBSemWaitTimeout(binary_semaphore_t *bsp,
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systime_t time) {
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return chSemWaitTimeout(&bsp->sem, time);
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}
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/**
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* @brief Reset operation on the binary semaphore.
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* @note The released threads can recognize they were waked up by a reset
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* rather than a signal because the @p bsemWait() will return
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* @p MSG_RESET instead of @p MSG_OK.
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* @note This function does not reschedule.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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* @param[in] taken new state of the binary semaphore
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* - @a false, the new state is not taken.
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* - @a true, the new state is taken.
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* .
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*
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* @iclass
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*/
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static inline void chBSemResetI(binary_semaphore_t *bsp, bool taken) {
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chDbgCheckClassI();
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chSemResetI(&bsp->sem, taken ? (cnt_t)0 : (cnt_t)1);
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}
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/**
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* @brief Reset operation on the binary semaphore.
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* @note The released threads can recognize they were waked up by a reset
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* rather than a signal because the @p bsemWait() will return
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* @p MSG_RESET instead of @p MSG_OK.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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* @param[in] taken new state of the binary semaphore
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* - @a false, the new state is not taken.
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* - @a true, the new state is taken.
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* .
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*
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* @api
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*/
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static inline void chBSemReset(binary_semaphore_t *bsp, bool taken) {
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chSemReset(&bsp->sem, taken ? (cnt_t)0 : (cnt_t)1);
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}
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/**
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* @brief Performs a signal operation on a binary semaphore.
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* @note This function does not reschedule.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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*
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* @iclass
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*/
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static inline void chBSemSignalI(binary_semaphore_t *bsp) {
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chDbgCheckClassI();
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if (bsp->sem.cnt < (cnt_t)1) {
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chSemSignalI(&bsp->sem);
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}
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}
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/**
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* @brief Performs a signal operation on a binary semaphore.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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*
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* @api
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*/
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static inline void chBSemSignal(binary_semaphore_t *bsp) {
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chSysLock();
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chBSemSignalI(bsp);
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chSchRescheduleS();
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chSysUnlock();
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}
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/**
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* @brief Returns the binary semaphore current state.
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*
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* @param[in] bsp pointer to a @p binary_semaphore_t structure
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* @return The binary semaphore current state.
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* @retval false if the binary semaphore is not taken.
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* @retval true if the binary semaphore is taken.
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*
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* @iclass
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*/
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static inline bool chBSemGetStateI(binary_semaphore_t *bsp) {
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chDbgCheckClassI();
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return (bsp->sem.cnt > (cnt_t)0) ? false : true;
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}
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#endif /* CH_CFG_USE_SEMAPHORES == TRUE */
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#endif /* CHBSEM_H */
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/** @} */
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