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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 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 chmboxes.h
* @brief Mailboxes macros and structures.
*
* @addtogroup mailboxes
* @{
*/
#ifndef _CHMBOXES_H_
#define _CHMBOXES_H_
#if CH_USE_MAILBOXES || defined(__DOXYGEN__)
/*
* Module dependencies check.
*/
#if !CH_USE_SEMAPHORES
#error "CH_USE_MAILBOXES requires CH_USE_SEMAPHORES"
#endif
/**
* @brief Structure representing a mailbox object.
*/
typedef struct {
msg_t *mb_buffer; /**< @brief Pointer to the mailbox
buffer. */
msg_t *mb_top; /**< @brief Pointer to the location
after the buffer. */
msg_t *mb_wrptr; /**< @brief Write pointer. */
msg_t *mb_rdptr; /**< @brief Read pointer. */
Semaphore mb_fullsem; /**< @brief Full counter
@p Semaphore. */
Semaphore mb_emptysem; /**< @brief Empty counter
@p Semaphore. */
} Mailbox;
#ifdef __cplusplus
extern "C" {
#endif
void chMBInit(Mailbox *mbp, msg_t *buf, cnt_t n);
void chMBReset(Mailbox *mbp);
msg_t chMBPost(Mailbox *mbp, msg_t msg, systime_t timeout);
msg_t chMBPostS(Mailbox *mbp, msg_t msg, systime_t timeout);
msg_t chMBPostAhead(Mailbox *mbp, msg_t msg, systime_t timeout);
msg_t chMBPostAheadS(Mailbox *mbp, msg_t msg, systime_t timeout);
msg_t chMBFetch(Mailbox *mbp, msg_t *msgp, systime_t timeout);
msg_t chMBFetchS(Mailbox *mbp, msg_t *msgp, systime_t timeout);
#ifdef __cplusplus
}
#endif
/**
* @brief Returns the mailbox buffer size.
*
* @param[in] mbp the pointer to an initialized Mailbox object
*
* @iclass
*/
#define chMBSizeI(mbp) \
((mbp)->mb_top - (mbp)->mb_buffer)
/**
* @brief Returns the number of free message slots into a mailbox.
* @note Can be invoked in any system state but if invoked out of a locked
* state then the returned value may change after reading.
* @note The returned value can be less than zero when there are waiting
* threads on the internal semaphore.
*
* @param[in] mbp the pointer to an initialized Mailbox object
* @return The number of empty message slots.
*
* @iclass
*/
#define chMBGetFreeCountI(mbp) chSemGetCounterI(&(mbp)->mb_emptysem)
/**
* @brief Returns the number of used message slots into a mailbox.
* @note Can be invoked in any system state but if invoked out of a locked
* state then the returned value may change after reading.
* @note The returned value can be less than zero when there are waiting
* threads on the internal semaphore.
*
* @param[in] mbp the pointer to an initialized Mailbox object
* @return The number of queued messages.
*
* @iclass
*/
#define chMBGetUsedCountI(mbp) chSemGetCounterI(&(mbp)->mb_fullsem)
/**
* @brief Returns the next message in the queue without removing it.
* @pre A message must be waiting in the queue for this function to work
* or it would return garbage. The correct way to use this macro is
* to use @p chMBGetFullCountI() and then use this macro, all within
* a lock state.
*
* @iclass
*/
#define chMBPeekI(mbp) (*(mbp)->mb_rdptr)
/**
* @brief Data part of a static mailbox initializer.
* @details This macro should be used when statically initializing a
* mailbox that is part of a bigger structure.
*
* @param[in] name the name of the mailbox variable
* @param[in] buffer pointer to the mailbox buffer area
* @param[in] size size of the mailbox buffer area
*/
#define _MAILBOX_DATA(name, buffer, size) { \
(msg_t *)(buffer), \
(msg_t *)(buffer) + size, \
(msg_t *)(buffer), \
(msg_t *)(buffer), \
_SEMAPHORE_DATA(name.mb_fullsem, 0), \
_SEMAPHORE_DATA(name.mb_emptysem, size), \
}
/**
* @brief Static mailbox initializer.
* @details Statically initialized mailboxes require no explicit
* initialization using @p chMBInit().
*
* @param[in] name the name of the mailbox variable
* @param[in] buffer pointer to the mailbox buffer area
* @param[in] size size of the mailbox buffer area
*/
#define MAILBOX_DECL(name, buffer, size) \
Mailbox name = _MAILBOX_DATA(name, buffer, size)
#endif /* CH_USE_MAILBOXES */
#endif /* _CHMBOXES_H_ */
/** @} */
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