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/*
ChibiOS/RT - Copyright (C) 2006-2007 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 mailboxes.h
* @brief Mailboxes macros and structures.
* @addtogroup Mailboxes
* @{
*/
#ifndef _MAILBOXES_H_
#define _MAILBOXES_H_
#if CH_USE_MAILBOXES
typedef struct {
msg_t *mb_buffer; /**< Pointer to the mailbox buffer.*/
msg_t *mb_top; /**< Pointer to the first location
after the buffer.*/
msg_t *mb_wrptr; /**< Write pointer.*/
msg_t *mb_rdptr; /**< Read pointer.*/
Semaphore mb_fullsem; /**< Full counter @p Semaphore.*/
Semaphore mb_emptysem; /**< 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 chMBPostAhead(Mailbox *mbp, msg_t msg, systime_t timeout);
msg_t chMBFetch(Mailbox *mbp, msg_t *msgp, systime_t timeout);
#ifdef __cplusplus
}
#endif
/**
* Returns the mailbox buffer size.
* @param[in] mbp the pointer to an initialized Mailbox object
*/
#define chMBSize(mbp) \
((mbp)->mb_top - (mbp)->mb_buffer)
/**
* Returns the free space into the mailbox.
* @param[in] mbp the pointer to an initialized Mailbox object
* @return The number of empty message slots.
* @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.
*/
#define chMBGetEmpty(mbp) chSemGetCounterI(&(mbp)->mb_emptysem)
/**
* Returns the number of messages into the mailbox.
* @param[in] mbp the pointer to an initialized Mailbox object
* @return The number of queued messages.
* @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.
*/
#define chMBGetFull(mbp) chSemGetCounterI(&(mbp)->mb_fullsem)
/**
* Returns the next message in the queue without removing it.
* @note 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 chMBGetFull() and then use this macro, all within a lock state.
*/
#define chMBPeek(mbp) (*(mbp)->mb_rdptr)
#endif /* CH_USE_MAILBOXES */
#endif /* _MAILBOXES_H_ */
/** @} */
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