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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/>.
*/
/**
* @addtogroup Messages
* @{
*/
#include <ch.h>
#ifdef CH_USE_MESSAGES
/**
* Sends a message to the specified thread. The client is stopped until the
* server executes a \p chMsgRelease() after receiving the message.
*
* @param tp the pointer to the thread
* @param msg the message, it can be a pointer to a complex structure
* @return the return message from \p chMsgRelease()
*/
msg_t chMsgSend(Thread *tp, msg_t msg) {
chSysLock();
#ifdef CH_USE_MESSAGES_PRIORITY
if (tp->p_flags & P_MSGBYPRIO)
prio_insert(currp, &tp->p_msgqueue);
else
fifo_insert(currp, &tp->p_msgqueue);
#else
fifo_insert(currp, &tp->p_msgqueue);
#endif
currp->p_msg = msg;
currp->p_wtthdp = tp;
if (tp->p_state == PRWTMSG)
chSchReadyI(tp);
chSchGoSleepS(PRSNDMSG);
msg = currp->p_rdymsg;
chSysUnlock();
return msg;
}
#ifdef CH_USE_MESSAGES_EVENT
/**
* Sends a message to the specified thread and atomically triggers an event.
* The client is stopped until the server executes a \p chMsgRelease()
* after receiving the message.
*
* @param tp the pointer to the thread
* @param msg the message, it can be a pointer to a complex structure
* @param esp the event source to pulse while sending the message
* @return the return message from \p chMsgRelease()
* @return the message return status from \p chMsgRelease()
* @note This function assumes that the receiving thread is not sleeping into
* a \p chMsgWait(). The use case is that the server thread is waiting
* for both messages AND events while waiting into \p chEvtWait().
*/
msg_t chMsgSendWithEvent(Thread *tp, msg_t msg, EventSource *esp) {
chSysLock();
chDbgAssert(tp->p_state != PRWTMSG, "chmsg.c, chMsgSendWithEvent()");
#ifdef CH_USE_MESSAGES_PRIORITY
if (tp->p_flags & P_MSGBYPRIO)
prio_insert(currp, &tp->p_msgqueue);
else
fifo_insert(currp, &tp->p_msgqueue);
#else
fifo_insert(currp, &tp->p_msgqueue);
#endif
chEvtSendI(esp);
currp->p_wtthdp = tp;
currp->p_msg = msg;
chSchGoSleepS(PRSNDMSG);
msg = currp->p_rdymsg;
chSysUnlock();
return msg;
}
#endif
/**
* Suspends the thread and waits for an incoming message.
*
* @return the pointer to the message structure. Note, it is always the
* message associated to the thread on the top of the messages queue.
* @note You can assume that the data contained in the message is stable until
* you invoke \p chMsgRelease() because the sending thread is
* suspended until then.
*/
msg_t chMsgWait(void) {
msg_t msg;
chSysLock();
if (!chMsgIsPendingI(currp))
chSchGoSleepS(PRWTMSG);
msg = chMsgGetI(currp);
chSysUnlock();
return msg;
}
/**
* Returns the next message in the queue.
*
* @return the pointer to the message structure. Note, it is always the
* message associated to the thread on the top of the messages queue.
* If the queue is empty then \p NULL is returned.
* @note You can assume that the data pointed by the message is stable until
* you invoke \p chMsgRelease() because the sending thread is
* suspended until then. Always remember that the message data is not
* copied between the sender and the receiver, just a pointer is passed.
*/
msg_t chMsgGet(void) {
msg_t msg;
chSysLock();
msg = chMsgIsPendingI(currp) ? chMsgGetI(currp) : (msg_t)NULL;
chSysUnlock();
return msg;
}
/**
* Releases the thread waiting on top of the messages queue.
*
* @param msg the message returned to the message sender
* @note You can call this function only if there is a message already in the
* queue else the result will be unpredictable (a crash most likely).
* Exiting from the \p chMsgWait() ensures you have at least one
* message in the queue so it is not a big deal.<br>
* The condition is not checked in order to make this code as fast as
* possible.
*/
void chMsgRelease(msg_t msg) {
chSysLock();
chDbgAssert(chMsgIsPendingI(currp), "chmsg.c, chMsgRelease()");
chSchWakeupS(fifo_remove(&currp->p_msgqueue), msg);
chSysUnlock();
}
#endif /* CH_USE_MESSAGES */
/** @} */
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