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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 chmboxes.c
* @brief Mailboxes code.
* @addtogroup Mailboxes
* @{
*/
#include <ch.h>
#if CH_USE_MAILBOXES
/**
* @brief Initializes a Mailbox object.
*
* @param[out] mbp the pointer to the Mailbox structure to be initialized
* @param[in] buf the circular messages buffer
* @param[in] n the buffer size as number of @p msg_t
*/
void chMBInit(Mailbox *mbp, msg_t *buf, cnt_t n) {
mbp->mb_buffer = mbp->mb_wrptr = mbp->mb_rdptr = buf;
mbp->mb_top = &buf[n];
chSemInit(&mbp->mb_emptysem, n);
chSemInit(&mbp->mb_fullsem, 0);
}
/**
* @brief Resets a Mailbox object.
* @details All the waiting threads are resumed with status @p RDY_RESET and
* the queued messages are lost.
*
* @param[in] mbp the pointer to an initialized Mailbox object
*/
void chMBReset(Mailbox *mbp) {
chSysLock();
mbp->mb_wrptr = mbp->mb_rdptr = mbp->mb_buffer;
chSemResetI(&mbp->mb_emptysem, mbp->mb_top - mbp->mb_buffer);
chSemResetI(&mbp->mb_fullsem, 0);
chSchRescheduleS();
chSysUnlock();
}
#if CH_USE_SEMAPHORES_TIMEOUT
/**
* @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 Mailbox object
* @param[in] msg the message to be posted on the mailbox
* @param[in] timeout the number of ticks before the operation fails
* @return The operation status.
* @retval RDY_OK if the message was correctly posted.
* @retval RDY_RESET if the mailbox was reset while waiting.
* @retval RDY_TIMEOUT if the operation timed out.
*/
msg_t chMBPost(Mailbox *mbp, msg_t msg, systime_t timeout) {
msg_t rdymsg;
chSysLock();
rdymsg = chSemWaitTimeoutS(&mbp->mb_emptysem, timeout);
if (rdymsg == RDY_OK) {
*mbp->mb_wrptr++ = msg;
if (mbp->mb_wrptr >= mbp->mb_top)
mbp->mb_wrptr = mbp->mb_buffer;
chSemSignalI(&mbp->mb_fullsem);
chSchRescheduleS();
}
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 Mailbox object
* @param[in] msg the message to be posted on the mailbox
* @param[in] timeout the number of ticks before the operation timeouts
* @return The operation status.
* @retval RDY_OK if the message was correctly posted.
* @retval RDY_RESET if the mailbox was reset while waiting.
* @retval RDY_TIMEOUT if the operation timed out.
*/
msg_t chMBPostAhead(Mailbox *mbp, msg_t msg, systime_t timeout) {
msg_t rdymsg;
chSysLock();
rdymsg = chSemWaitTimeoutS(&mbp->mb_emptysem, timeout);
if (rdymsg == RDY_OK) {
if (--mbp->mb_rdptr < mbp->mb_buffer)
mbp->mb_rdptr = mbp->mb_top - 1;
*mbp->mb_rdptr = msg;
chSemSignalI(&mbp->mb_fullsem);
chSchRescheduleS();
}
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 Mailbox object
* @param[out] msgp pointer to a message variable for the received message
* @param[in] timeout the number of ticks before the operation timeouts
* @return The operation status.
* @retval RDY_OK if a message was correctly fetched.
* @retval RDY_RESET if the mailbox was reset while waiting.
* @retval RDY_TIMEOUT if the operation timed out.
*/
msg_t chMBFetch(Mailbox *mbp, msg_t *msgp, systime_t timeout) {
msg_t rdymsg;
chSysLock();
rdymsg = chSemWaitTimeoutS(&mbp->mb_fullsem, timeout);
if (rdymsg == RDY_OK) {
*msgp = *mbp->mb_rdptr++;
if (mbp->mb_rdptr >= mbp->mb_top)
mbp->mb_rdptr = mbp->mb_buffer;
chSemSignalI(&mbp->mb_emptysem);
chSchRescheduleS();
}
chSysUnlock();
return rdymsg;
}
#endif /* CH_USE_SEMAPHORES_TIMEOUT */
#endif /* CH_USE_MAILBOXES */
/** @} */
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