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222 lines
8.0 KiB
C
222 lines
8.0 KiB
C
/*
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ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio.
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This file is part of ChibiOS.
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ChibiOS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file rt/src/chmsg.c
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* @brief Messages code.
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*
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* @addtogroup messages
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* @details Synchronous inter-thread messages APIs and services.
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* <h2>Operation Mode</h2>
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* Synchronous messages are an easy to use and fast IPC mechanism,
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* threads can both act as message servers and/or message clients,
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* the mechanism allows data to be carried in both directions. Note
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* that messages are not copied between the client and server threads
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* but just a pointer passed so the exchange is very time
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* efficient.<br>
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* Messages are scalar data types of type @p msg_t that are guaranteed
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* to be size compatible with data pointers. Note that on some
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* architectures function pointers can be larger that @p msg_t.<br>
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* Messages are usually processed in FIFO order but it is possible to
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* process them in priority order by enabling the
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* @p CH_CFG_USE_MESSAGES_PRIORITY option in @p chconf.h.<br>
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* @pre In order to use the message APIs the @p CH_CFG_USE_MESSAGES option
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* must be enabled in @p chconf.h.
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* @post Enabling messages requires 6-12 (depending on the architecture)
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* extra bytes in the @p thread_t structure.
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* @{
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*/
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#include "ch.h"
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#if (CH_CFG_USE_MESSAGES == TRUE) || defined(__DOXYGEN__)
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/*===========================================================================*/
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/* Module exported variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local types. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local functions. */
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/*===========================================================================*/
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#if CH_CFG_USE_MESSAGES_PRIORITY == TRUE
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#define msg_insert(tp, qp) queue_prio_insert(tp, qp)
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#else
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#define msg_insert(tp, qp) queue_insert(tp, qp)
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#endif
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/*===========================================================================*/
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/* Module exported functions. */
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/*===========================================================================*/
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/**
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* @brief Sends a message to the specified thread.
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* @details The sender is stopped until the receiver executes a
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* @p chMsgRelease()after receiving the message.
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*
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* @param[in] tp the pointer to the thread
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* @param[in] msg the message
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* @return The answer message from @p chMsgRelease().
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*
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* @api
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*/
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msg_t chMsgSend(thread_t *tp, msg_t msg) {
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thread_t *ctp = currp;
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chDbgCheck(tp != NULL);
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chSysLock();
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ctp->u.sentmsg = msg;
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msg_insert(ctp, &tp->msgqueue);
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if (tp->state == CH_STATE_WTMSG) {
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(void) chSchReadyI(tp);
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}
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chSchGoSleepS(CH_STATE_SNDMSGQ);
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msg = ctp->u.rdymsg;
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chSysUnlock();
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return msg;
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}
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/**
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* @brief Suspends the thread and waits for an incoming message.
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* @post After receiving a message the function @p chMsgGet() must be
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* called in order to retrieve the message and then @p chMsgRelease()
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* must be invoked in order to acknowledge the reception and send
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* the answer.
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* @note If the message is a pointer then you can assume that the data
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* pointed by the message is stable until you invoke @p chMsgRelease()
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* because the sending thread is suspended until then.
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* @note The reference counter of the sender thread is not increased, the
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* returned pointer is a temporary reference.
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*
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* @return A pointer to the thread carrying the message.
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*
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* @sclass
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*/
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thread_t *chMsgWaitS(void) {
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thread_t *tp;
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chDbgCheckClassS();
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if (!chMsgIsPendingI(currp)) {
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chSchGoSleepS(CH_STATE_WTMSG);
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}
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tp = queue_fifo_remove(&currp->msgqueue);
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tp->state = CH_STATE_SNDMSG;
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return tp;
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}
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/**
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* @brief Suspends the thread and waits for an incoming message or a
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* timeout to occur.
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* @post After receiving a message the function @p chMsgGet() must be
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* called in order to retrieve the message and then @p chMsgRelease()
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* must be invoked in order to acknowledge the reception and send
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* the answer.
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* @note If the message is a pointer then you can assume that the data
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* pointed by the message is stable until you invoke @p chMsgRelease()
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* because the sending thread is suspended until then.
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* @note The reference counter of the sender thread is not increased, the
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* returned pointer is a temporary reference.
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*
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* @param[in] timeout the number of ticks before the operation timeouts,
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* the following special values are allowed:
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* - @a TIME_INFINITE no timeout.
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* .
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* @return A pointer to the thread carrying the message.
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* @retval NULL if a timeout occurred.
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*
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* @sclass
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*/
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thread_t *chMsgWaitTimeoutS(sysinterval_t timeout) {
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thread_t *tp;
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chDbgCheckClassS();
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if (!chMsgIsPendingI(currp)) {
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if (chSchGoSleepTimeoutS(CH_STATE_WTMSG, timeout) != MSG_OK) {
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return NULL;
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}
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}
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tp = queue_fifo_remove(&currp->msgqueue);
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tp->state = CH_STATE_SNDMSG;
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return tp;
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}
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/**
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* @brief Poll to check for an incoming message.
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* @post If a message is available the function @p chMsgGet() must be
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* called in order to retrieve the message and then @p chMsgRelease()
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* must be invoked in order to acknowledge the reception and send
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* the answer.
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* @note If the message is a pointer then you can assume that the data
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* pointed by the message is stable until you invoke @p chMsgRelease()
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* because the sending thread is suspended until then.
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* @note The reference counter of the sender thread is not increased, the
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* returned pointer is a temporary reference.
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*
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* @return Result of the poll.
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* @retval NULL if no incoming message waiting.
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*
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* @sclass
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*/
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thread_t *chMsgPollS(void) {
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thread_t *tp = NULL;
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if (chMsgIsPendingI(currp)) {
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tp = queue_fifo_remove(&currp->msgqueue);
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tp->state = CH_STATE_SNDMSG;
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}
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return tp;
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}
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/**
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* @brief Releases a sender thread specifying a response message.
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* @pre Invoke this function only after a message has been received
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* using @p chMsgWait().
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*
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* @param[in] tp pointer to the thread
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* @param[in] msg message to be returned to the sender
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*
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* @api
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*/
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void chMsgRelease(thread_t *tp, msg_t msg) {
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chSysLock();
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chDbgAssert(tp->state == CH_STATE_SNDMSG, "invalid state");
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chMsgReleaseS(tp, msg);
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chSysUnlock();
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}
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#endif /* CH_CFG_USE_MESSAGES == TRUE */
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/** @} */
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