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/*
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 <http://www.gnu.org/licenses/>.
*/
/**
* @file nil/include/chsem.h
* @brief Nil RTOS semaphores header file.
*
* @addtogroup NIL_SEMAPHORES
* @{
*/
#ifndef CHSEM_H
#define CHSEM_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. */
/*===========================================================================*/
/*===========================================================================*/
/* Module macros. */
/*===========================================================================*/
/**
* @name Macro 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
*/
#define chSemObjectInit(sp, n) ((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.
* @note This function implicitly sends @p MSG_RESET as message.
*
* @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.
*
* @api
*/
#define chSemReset(sp, n) chSemResetWithMessage(sp, n, MSG_RESET)
/**
* @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.
* @note This function implicitly sends @p MSG_RESET as message.
*
* @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.
*
* @iclass
*/
#define chSemResetI(sp, n) chSemResetWithMessageI(sp, n, MSG_RESET)
/**
* @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 CH_MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval CH_MSG_RST if the semaphore has been reset using @p chSemReset().
*
* @api
*/
#define chSemWait(sp) chSemWaitTimeout(sp, TIME_INFINITE)
/**
* @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 CH_MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval CH_MSG_RST if the semaphore has been reset using @p chSemReset().
*
* @sclass
*/
#define chSemWaitS(sp) chSemWaitTimeoutS(sp, TIME_INFINITE)
/**
* @brief Decreases the semaphore counter.
* @details This macro can be used when the counter is known to be positive.
*
* @param[in] sp pointer to a @p semaphore_t structure
*
* @iclass
*/
#define chSemFastWaitI(sp) ((sp)->cnt--)
/**
* @brief Increases the semaphore counter.
* @details This macro can be used when the counter is known to be not
* negative.
*
* @param[in] sp pointer to a @p semaphore_t structure
*
* @iclass
*/
#define chSemFastSignalI(sp) ((sp)->cnt++)
/**
* @brief Returns the semaphore counter current value.
*
* @iclass
*/
#define chSemGetCounterI(sp) ((sp)->cnt)
/** @} */
/*===========================================================================*/
/* External declarations. */
/*===========================================================================*/
#ifdef __cplusplus
extern "C" {
#endif
msg_t chSemWaitTimeout(semaphore_t *sp, sysinterval_t timeout);
msg_t chSemWaitTimeoutS(semaphore_t *sp, sysinterval_t timeout);
void chSemSignal(semaphore_t *sp);
void chSemSignalI(semaphore_t *sp);
void chSemResetWithMessage(semaphore_t *sp, cnt_t n, msg_t msg);
void chSemResetWithMessageI(semaphore_t *sp, cnt_t n, msg_t msg);
#ifdef __cplusplus
}
#endif
#endif /* CH_CFG_USE_SEMAPHORES == TRUE */
#endif /* CHSEM_H */
/** @} */
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