/* ChibiOS - Copyright (C) 2006..2016 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 chbsem.h * @brief Binary semaphores structures and macros. * * @addtogroup binary_semaphores * @details Binary semaphores related APIs and services. *

Operation mode

* Binary semaphores are implemented as a set of inline functions * 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: * - Taken, 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. * - Not taken, when its counter has a value of one. * . * Binary semaphores are different from mutexes because there is no * 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.
* In order to use the binary semaphores APIs the * @p CH_CFG_USE_SEMAPHORES option must be enabled in @p chconf.h. * @{ */ #ifndef CHBSEM_H #define CHBSEM_H #if (CH_CFG_USE_SEMAPHORES == TRUE) || defined(__DOXYGEN__) /*===========================================================================*/ /* Module constants. */ /*===========================================================================*/ /*===========================================================================*/ /* Module pre-compile time settings. */ /*===========================================================================*/ /*===========================================================================*/ /* Derived constants and error checks. */ /*===========================================================================*/ /*===========================================================================*/ /* Module data structures and types. */ /*===========================================================================*/ /** * @extends semaphore_t * * @brief Binary semaphore type. */ typedef struct ch_binary_semaphore { semaphore_t sem; } binary_semaphore_t; /*===========================================================================*/ /* Module macros. */ /*===========================================================================*/ /** * @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.sem, ((taken) ? 0 : 1))} /** * @brief Static semaphore initializer. * @details Statically initialized semaphores require no explicit * initialization using @p chBSemInit(). * * @param[in] name the name of the semaphore variable * @param[in] taken the semaphore initial state */ #define BSEMAPHORE_DECL(name, taken) \ binary_semaphore_t name = _BSEMAPHORE_DATA(name, taken) /*===========================================================================*/ /* External declarations. */ /*===========================================================================*/ /*===========================================================================*/ /* Module inline functions. */ /*===========================================================================*/ /** * @brief Initializes a binary semaphore. * * @param[out] bsp pointer to a @p binary_semaphore_t 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 */ static inline void chBSemObjectInit(binary_semaphore_t *bsp, bool taken) { chSemObjectInit(&bsp->sem, taken ? (cnt_t)0 : (cnt_t)1); } /** * @brief Wait operation on the binary semaphore. * * @param[in] bsp pointer to a @p binary_semaphore_t structure * @return A message specifying how the invoking thread has been * released from the semaphore. * @retval MSG_OK if the binary semaphore has been successfully taken. * @retval MSG_RESET if the binary semaphore has been reset using * @p bsemReset(). * * @api */ static inline msg_t chBSemWait(binary_semaphore_t *bsp) { return chSemWait(&bsp->sem); } /** * @brief Wait operation on the binary semaphore. * * @param[in] bsp pointer to a @p binary_semaphore_t structure * @return A message specifying how the invoking thread has been * released from the semaphore. * @retval MSG_OK if the binary semaphore has been successfully taken. * @retval MSG_RESET if the binary semaphore has been reset using * @p bsemReset(). * * @sclass */ static inline msg_t chBSemWaitS(binary_semaphore_t *bsp) { chDbgCheckClassS(); return chSemWaitS(&bsp->sem); } /** * @brief Wait operation on the binary semaphore. * * @param[in] bsp pointer to a @p binary_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 binary semaphore has been successfully taken. * @retval MSG_RESET if the binary semaphore has been reset using * @p bsemReset(). * @retval MSG_TIMEOUT if the binary semaphore has not been signaled or reset * within the specified timeout. * * @sclass */ static inline msg_t chBSemWaitTimeoutS(binary_semaphore_t *bsp, sysinterval_t timeout) { chDbgCheckClassS(); return chSemWaitTimeoutS(&bsp->sem, timeout); } /** * @brief Wait operation on the binary semaphore. * * @param[in] bsp pointer to a @p binary_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 binary semaphore has been successfully taken. * @retval MSG_RESET if the binary semaphore has been reset using * @p bsemReset(). * @retval MSG_TIMEOUT if the binary semaphore has not been signaled or reset * within the specified timeout. * * @api */ static inline msg_t chBSemWaitTimeout(binary_semaphore_t *bsp, sysinterval_t timeout) { return chSemWaitTimeout(&bsp->sem, timeout); } /** * @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 MSG_RESET instead of @p MSG_OK. * @note This function does not reschedule. * * @param[in] bsp pointer to a @p binary_semaphore_t 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 */ static inline void chBSemResetI(binary_semaphore_t *bsp, bool taken) { chDbgCheckClassI(); chSemResetI(&bsp->sem, taken ? (cnt_t)0 : (cnt_t)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 MSG_RESET instead of @p MSG_OK. * * @param[in] bsp pointer to a @p binary_semaphore_t 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 */ static inline void chBSemReset(binary_semaphore_t *bsp, bool taken) { chSemReset(&bsp->sem, taken ? (cnt_t)0 : (cnt_t)1); } /** * @brief Performs a signal operation on a binary semaphore. * @note This function does not reschedule. * * @param[in] bsp pointer to a @p binary_semaphore_t structure * * @iclass */ static inline void chBSemSignalI(binary_semaphore_t *bsp) { chDbgCheckClassI(); if (bsp->sem.cnt < (cnt_t)1) { chSemSignalI(&bsp->sem); } } /** * @brief Performs a signal operation on a binary semaphore. * * @param[in] bsp pointer to a @p binary_semaphore_t structure * * @api */ static inline void chBSemSignal(binary_semaphore_t *bsp) { chSysLock(); chBSemSignalI(bsp); chSchRescheduleS(); chSysUnlock(); } /** * @brief Returns the binary semaphore current state. * * @param[in] bsp pointer to a @p binary_semaphore_t 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 */ static inline bool chBSemGetStateI(binary_semaphore_t *bsp) { chDbgCheckClassI(); return (bsp->sem.cnt > (cnt_t)0) ? false : true; } #endif /* CH_CFG_USE_SEMAPHORES == TRUE */ #endif /* CHBSEM_H */ /** @} */ 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327