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/*
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 <http://www.gnu.org/licenses/>.
*/
/**
* @file chmboxes.c
* @brief Mailboxes code.
*
* @addtogroup mailboxes
* @details Asynchronous messages.
* <h2>Operation mode</h2>
* A mailbox is an asynchronous communication mechanism.<br>
* Operations defined for mailboxes:
* - <b>Post</b>: Posts a message on the mailbox in FIFO order.
* - <b>Post Ahead</b>: Posts a message on the mailbox with urgent
* priority.
* - <b>Fetch</b>: A message is fetched from the mailbox and removed
* from the queue.
* - <b>Reset</b>: The mailbox is emptied and all the stored messages
* are lost.
* .
* A message is a variable of type msg_t that is guaranteed to have
* the same size of and be compatible with (data) pointers (anyway an
* explicit cast is needed).
* If larger messages need to be exchanged then a pointer to a
* structure can be posted in the mailbox but the posting side has
* no predefined way to know when the message has been processed. A
* possible approach is to allocate memory (from a memory pool for
* example) from the posting side and free it on the fetching side.
* Another approach is to set a "done" flag into the structure pointed
* by the message.
* @pre In order to use the mailboxes APIs the @p CH_CFG_USE_MAILBOXES
* option must be enabled in @p chconf.h.
* @note Compatible with RT and NIL.
* @{
*/
#include "ch.h"
#if (CH_CFG_USE_MAILBOXES == TRUE) || defined(__DOXYGEN__)
/*===========================================================================*/
/* Module exported variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local types. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local functions. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Initializes a @p mailbox_t object.
*
* @param[out] mbp the pointer to the @p mailbox_t structure to be
* initialized
* @param[in] buf pointer to the messages buffer as an array of @p msg_t
* @param[in] n number of elements in the buffer array
*
* @init
*/
void chMBObjectInit(mailbox_t *mbp, msg_t *buf, size_t n) {
chDbgCheck((mbp != NULL) && (buf != NULL) && (n > (size_t)0));
mbp->buffer = buf;
mbp->rdptr = buf;
mbp->wrptr = buf;
mbp->top = &buf[n];
mbp->cnt = (size_t)0;
mbp->reset = false;
chThdQueueObjectInit(&mbp->qw);
chThdQueueObjectInit(&mbp->qr);
}
/**
* @brief Resets a @p mailbox_t object.
* @details All the waiting threads are resumed with status @p MSG_RESET and
* the queued messages are lost.
* @post The mailbox is in reset state, all operations will fail and
* return @p MSG reset until the mailbox is enabled again using
* @p chMBResumeX().
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
*
* @api
*/
void chMBReset(mailbox_t *mbp) {
chSysLock();
chMBResetI(mbp);
chSchRescheduleS();
chSysUnlock();
}
/**
* @brief Resets a @p mailbox_t object.
* @details All the waiting threads are resumed with status @p MSG_RESET and
* the queued messages are lost.
* @post The mailbox is in reset state, all operations will fail and
* return @p MSG reset until the mailbox is enabled again using
* @p chMBResumeX().
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
*
* @api
*/
void chMBResetI(mailbox_t *mbp) {
chDbgCheckClassI();
chDbgCheck(mbp != NULL);
mbp->wrptr = mbp->buffer;
mbp->rdptr = mbp->buffer;
mbp->cnt = (size_t)0;
mbp->reset = true;
chThdDequeueAllI(&mbp->qw, MSG_RESET);
chThdDequeueAllI(&mbp->qr, MSG_RESET);
}
/**
* @brief Posts a message into a mailbox.
* @details The invoking thread waits until a empty slot in the mailbox becomes
* available or the specified time runs out.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[in] msg the message to be posted on the mailbox
* @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 The operation status.
* @retval MSG_OK if a message has been correctly posted.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the operation has timed out.
*
* @api
*/
msg_t chMBPostTimeout(mailbox_t *mbp, msg_t msg, sysinterval_t timeout) {
msg_t rdymsg;
chSysLock();
rdymsg = chMBPostTimeoutS(mbp, msg, timeout);
chSysUnlock();
return rdymsg;
}
/**
* @brief Posts a message into a mailbox.
* @details The invoking thread waits until a empty slot in the mailbox becomes
* available or the specified time runs out.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[in] msg the message to be posted on the mailbox
* @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 The operation status.
* @retval MSG_OK if a message has been correctly posted.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the operation has timed out.
*
* @sclass
*/
msg_t chMBPostTimeoutS(mailbox_t *mbp, msg_t msg, sysinterval_t timeout) {
msg_t rdymsg;
chDbgCheckClassS();
chDbgCheck(mbp != NULL);
do {
/* If the mailbox is in reset state then returns immediately.*/
if (mbp->reset) {
return MSG_RESET;
}
/* Is there a free message slot in queue? if so then post.*/
if (chMBGetFreeCountI(mbp) > (size_t)0) {
*mbp->wrptr++ = msg;
if (mbp->wrptr >= mbp->top) {
mbp->wrptr = mbp->buffer;
}
mbp->cnt++;
/* If there is a reader waiting then makes it ready.*/
chThdDequeueNextI(&mbp->qr, MSG_OK);
chSchRescheduleS();
return MSG_OK;
}
/* No space in the queue, waiting for a slot to become available.*/
rdymsg = chThdEnqueueTimeoutS(&mbp->qw, timeout);
} while (rdymsg == MSG_OK);
return rdymsg;
}
/**
* @brief Posts a message into a mailbox.
* @details This variant is non-blocking, the function returns a timeout
* condition if the queue is full.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[in] msg the message to be posted on the mailbox
* @return The operation status.
* @retval MSG_OK if a message has been correctly posted.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the mailbox is full and the message cannot be
* posted.
*
* @iclass
*/
msg_t chMBPostI(mailbox_t *mbp, msg_t msg) {
chDbgCheckClassI();
chDbgCheck(mbp != NULL);
/* If the mailbox is in reset state then returns immediately.*/
if (mbp->reset) {
return MSG_RESET;
}
/* Is there a free message slot in queue? if so then post.*/
if (chMBGetFreeCountI(mbp) > (size_t)0) {
*mbp->wrptr++ = msg;
if (mbp->wrptr >= mbp->top) {
mbp->wrptr = mbp->buffer;
}
mbp->cnt++;
/* If there is a reader waiting then makes it ready.*/
chThdDequeueNextI(&mbp->qr, MSG_OK);
return MSG_OK;
}
/* No space, immediate timeout.*/
return MSG_TIMEOUT;
}
/**
* @brief Posts an high priority message into a mailbox.
* @details The invoking thread waits until a empty slot in the mailbox becomes
* available or the specified time runs out.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[in] msg the message to be posted on the mailbox
* @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 The operation status.
* @retval MSG_OK if a message has been correctly posted.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the operation has timed out.
*
* @api
*/
msg_t chMBPostAheadTimeout(mailbox_t *mbp, msg_t msg, sysinterval_t timeout) {
msg_t rdymsg;
chSysLock();
rdymsg = chMBPostAheadTimeoutS(mbp, msg, timeout);
chSysUnlock();
return rdymsg;
}
/**
* @brief Posts an high priority message into a mailbox.
* @details The invoking thread waits until a empty slot in the mailbox becomes
* available or the specified time runs out.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[in] msg the message to be posted on the mailbox
* @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 The operation status.
* @retval MSG_OK if a message has been correctly posted.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the operation has timed out.
*
* @sclass
*/
msg_t chMBPostAheadTimeoutS(mailbox_t *mbp, msg_t msg, sysinterval_t timeout) {
msg_t rdymsg;
chDbgCheckClassS();
chDbgCheck(mbp != NULL);
do {
/* If the mailbox is in reset state then returns immediately.*/
if (mbp->reset) {
return MSG_RESET;
}
/* Is there a free message slot in queue? if so then post.*/
if (chMBGetFreeCountI(mbp) > (size_t)0) {
if (--mbp->rdptr < mbp->buffer) {
mbp->rdptr = mbp->top - 1;
}
*mbp->rdptr = msg;
mbp->cnt++;
/* If there is a reader waiting then makes it ready.*/
chThdDequeueNextI(&mbp->qr, MSG_OK);
chSchRescheduleS();
return MSG_OK;
}
/* No space in the queue, waiting for a slot to become available.*/
rdymsg = chThdEnqueueTimeoutS(&mbp->qw, timeout);
} while (rdymsg == MSG_OK);
return rdymsg;
}
/**
* @brief Posts an high priority message into a mailbox.
* @details This variant is non-blocking, the function returns a timeout
* condition if the queue is full.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[in] msg the message to be posted on the mailbox
* @return The operation status.
* @retval MSG_OK if a message has been correctly posted.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the mailbox is full and the message cannot be
* posted.
*
* @iclass
*/
msg_t chMBPostAheadI(mailbox_t *mbp, msg_t msg) {
chDbgCheckClassI();
chDbgCheck(mbp != NULL);
/* If the mailbox is in reset state then returns immediately.*/
if (mbp->reset) {
return MSG_RESET;
}
/* Is there a free message slot in queue? if so then post.*/
if (chMBGetFreeCountI(mbp) > (size_t)0) {
if (--mbp->rdptr < mbp->buffer) {
mbp->rdptr = mbp->top - 1;
}
*mbp->rdptr = msg;
mbp->cnt++;
/* If there is a reader waiting then makes it ready.*/
chThdDequeueNextI(&mbp->qr, MSG_OK);
return MSG_OK;
}
/* No space, immediate timeout.*/
return MSG_TIMEOUT;
}
/**
* @brief Retrieves a message from a mailbox.
* @details The invoking thread waits until a message is posted in the mailbox
* or the specified time runs out.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[out] msgp pointer to a message variable for the received message
* @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 The operation status.
* @retval MSG_OK if a message has been correctly fetched.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the operation has timed out.
*
* @api
*/
msg_t chMBFetchTimeout(mailbox_t *mbp, msg_t *msgp, sysinterval_t timeout) {
msg_t rdymsg;
chSysLock();
rdymsg = chMBFetchTimeoutS(mbp, msgp, timeout);
chSysUnlock();
return rdymsg;
}
/**
* @brief Retrieves a message from a mailbox.
* @details The invoking thread waits until a message is posted in the mailbox
* or the specified time runs out.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[out] msgp pointer to a message variable for the received message
* @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 The operation status.
* @retval MSG_OK if a message has been correctly fetched.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the operation has timed out.
*
* @sclass
*/
msg_t chMBFetchTimeoutS(mailbox_t *mbp, msg_t *msgp, sysinterval_t timeout) {
msg_t rdymsg;
chDbgCheckClassS();
chDbgCheck((mbp != NULL) && (msgp != NULL));
do {
/* If the mailbox is in reset state then returns immediately.*/
if (mbp->reset) {
return MSG_RESET;
}
/* Is there a message in queue? if so then fetch.*/
if (chMBGetUsedCountI(mbp) > (size_t)0) {
*msgp = *mbp->rdptr++;
if (mbp->rdptr >= mbp->top) {
mbp->rdptr = mbp->buffer;
}
mbp->cnt--;
/* If there is a writer waiting then makes it ready.*/
chThdDequeueNextI(&mbp->qw, MSG_OK);
chSchRescheduleS();
return MSG_OK;
}
/* No message in the queue, waiting for a message to become available.*/
rdymsg = chThdEnqueueTimeoutS(&mbp->qr, timeout);
} while (rdymsg == MSG_OK);
return rdymsg;
}
/**
* @brief Retrieves a message from a mailbox.
* @details This variant is non-blocking, the function returns a timeout
* condition if the queue is empty.
*
* @param[in] mbp the pointer to an initialized @p mailbox_t object
* @param[out] msgp pointer to a message variable for the received message
* @return The operation status.
* @retval MSG_OK if a message has been correctly fetched.
* @retval MSG_RESET if the mailbox has been reset.
* @retval MSG_TIMEOUT if the mailbox is empty and a message cannot be
* fetched.
*
* @iclass
*/
msg_t chMBFetchI(mailbox_t *mbp, msg_t *msgp) {
chDbgCheckClassI();
chDbgCheck((mbp != NULL) && (msgp != NULL));
/* If the mailbox is in reset state then returns immediately.*/
if (mbp->reset) {
return MSG_RESET;
}
/* Is there a message in queue? if so then fetch.*/
if (chMBGetUsedCountI(mbp) > (size_t)0) {
*msgp = *mbp->rdptr++;
if (mbp->rdptr >= mbp->top) {
mbp->rdptr = mbp->buffer;
}
mbp->cnt--;
/* If there is a writer waiting then makes it ready.*/
chThdDequeueNextI(&mbp->qw, MSG_OK);
return MSG_OK;
}
/* No message, immediate timeout.*/
return MSG_TIMEOUT;
}
#endif /* CH_CFG_USE_MAILBOXES == TRUE */
/** @} */
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