/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011 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 chqueues.c
* @brief I/O Queues code.
*
* @addtogroup io_queues
* @details ChibiOS/RT queues are mostly used in serial-like device drivers.
* The device drivers are usually designed to have a lower side
* (lower driver, it is usually an interrupt service routine) and an
* upper side (upper driver, accessed by the application threads).<br>
* There are several kind of queues:<br>
* - <b>Input queue</b>, unidirectional queue where the writer is the
* lower side and the reader is the upper side.
* - <b>Output queue</b>, unidirectional queue where the writer is the
* upper side and the reader is the lower side.
* - <b>Full duplex queue</b>, bidirectional queue. Full duplex queues
* are implemented by pairing an input queue and an output queue
* together.
* .
* I/O queues are usually used as an implementation layer for the I/O
* channels interface, also see @ref io_channels.
* @pre In order to use the I/O queues the @p CH_USE_QUEUES option must
* be enabled in @p chconf.h.
* @{
*/
#include "ch.h"
#if CH_USE_QUEUES || defined(__DOXYGEN__)
/**
* @brief Puts the invoking thread into the queue's threads queue.
*
* @param[out] qp pointer to an @p GenericQueue structure
* @param[in] time 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 A message specifying how the invoking thread has been
* released from threads queue.
* @retval Q_OK is the normal exit, thread signaled.
* @retval Q_RESET if the queue has been reset.
* @retval Q_TIMEOUT if the queue operation timed out.
*/
static msg_t qwait(GenericQueue *qp, systime_t time) {
if (TIME_IMMEDIATE == time)
return Q_TIMEOUT;
currp->p_u.wtobjp = qp;
queue_insert(currp, &qp->q_waiting);
return chSchGoSleepTimeoutS(THD_STATE_WTQUEUE, time);
}
/**
* @brief Initializes an input queue.
* @details A Semaphore is internally initialized and works as a counter of
* the bytes contained in the queue.
* @note The callback is invoked from within the S-Locked system state,
* see @ref system_states.
*
* @param[out] iqp pointer to an @p InputQueue structure
* @param[in] bp pointer to a memory area allocated as queue buffer
* @param[in] size size of the queue buffer
* @param[in] infy pointer to a callback function that is invoked when
* data is read from the queue. The value can be @p NULL.
*
* @init
*/
void chIQInit(InputQueue *iqp, uint8_t *bp, size_t size, qnotify_t infy) {
queue_init(&iqp->q_waiting);
iqp->q_counter = 0;
iqp->q_buffer = iqp->q_rdptr = iqp->q_wrptr = bp;
iqp->q_top = bp + size;
iqp->q_notify = infy;
}
/**
* @brief Resets an input queue.
* @details All the data in the input queue is erased and lost, any waiting
* thread is resumed with status @p Q_RESET.
* @note A reset operation can be used by a low level driver in order to
* obtain immediate attention from the high level layers.
*
* @param[in] iqp pointer to an @p InputQueue structure
*
* @iclass
*/
void chIQResetI(InputQueue *iqp) {
chDbgCheckClassI();
iqp->q_rdptr = iqp->q_wrptr = iqp->q_buffer;
iqp->q_counter = 0;
while (notempty(&iqp->q_waiting))
chSchReadyI(fifo_remove(&iqp->q_waiting))->p_u.rdymsg = Q_RESET;
}
/**
* @brief Input queue write.
* @details A byte value is written into the low end of an input queue.
*
* @param[in] iqp pointer to an @p InputQueue structure
* @param[in] b the byte value to be written in the queue
* @return The operation status.
* @retval Q_OK if the operation has been completed with success.
* @retval Q_FULL if the queue is full and the operation cannot be
* completed.
*
* @iclass
*/
msg_t chIQPutI(InputQueue *iqp, uint8_t b) {
chDbgCheckClassI();
if (chIQIsFullI(iqp))
return Q_FULL;
iqp->q_counter++;
*iqp->q_wrptr++ = b;
if (iqp->q_wrptr >= iqp->q_top)
iqp->q_wrptr = iqp->q_buffer;
if (notempty(&iqp->q_waiting))
chSchReadyI(fifo_remove(&iqp->q_waiting))->p_u.rdymsg = Q_OK;
return Q_OK;
}
/**
* @brief Input queue read with timeout.
* @details This function reads a byte value from an input queue. If the queue
* is empty then the calling thread is suspended until a byte arrives
* in the queue or a timeout occurs.
* @note The callback is invoked if the queue is empty before entering the
* @p THD_STATE_WTQUEUE state in order to solicit the low level to
* start queue filling.
*
* @param[in] iqp pointer to an @p InputQueue structure
* @param[in] time 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 A byte value from the queue.
* @retval Q_TIMEOUT if the specified time expired.
* @retval Q_RESET if the queue has been reset.
*
* @api
*/
msg_t chIQGetTimeout(InputQueue *iqp, systime_t time) {
uint8_t b;
chSysLock();
while (chIQIsEmptyI(iqp)) {
msg_t msg;
if (iqp->q_notify)
iqp->q_notify(iqp);
if ((msg = qwait((GenericQueue *)iqp, time)) < Q_OK) {
chSysUnlock();
return msg;
}
}
iqp->q_counter--;
b = *iqp->q_rdptr++;
if (iqp->q_rdptr >= iqp->q_top)
iqp->q_rdptr = iqp->q_buffer;
chSysUnlock();
return b;
}
/**
* @brief Input queue read with timeout.
* @details The function reads data from an input queue into a buffer. The
* operation completes when the specified amount of data has been
* transferred or after the specified timeout or if the queue has
* been reset.
* @note The function is not atomic, if you need atomicity it is suggested
* to use a semaphore or a mutex for mutual exclusion.
* @note The callback is invoked if the queue is empty before entering the
* @p THD_STATE_WTQUEUE state in order to solicit the low level to
* start queue filling.
*
* @param[in] iqp pointer to an @p InputQueue structure
* @param[out] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred, the
* value 0 is reserved
* @param[in] time 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 number of bytes effectively transferred.
*
* @api
*/
size_t chIQReadTimeout(InputQueue *iqp, uint8_t *bp,
size_t n, systime_t time) {
qnotify_t nfy = iqp->q_notify;
size_t r = 0;
chDbgCheck(n > 0, "chIQReadTimeout");
chSysLock();
while (TRUE) {
while (chIQIsEmptyI(iqp)) {
if (nfy)
nfy(iqp);
if (qwait((GenericQueue *)iqp, time) != Q_OK) {
chSysUnlock();
return r;
}
}
iqp->q_counter--;
*bp++ = *iqp->q_rdptr++;
if (iqp->q_rdptr >= iqp->q_top)
iqp->q_rdptr = iqp->q_buffer;
chSysUnlock(); /* Gives a preemption chance in a controlled point.*/
r++;
if (--n == 0)
return r;
chSysLock();
}
}
/**
* @brief Initializes an output queue.
* @details A Semaphore is internally initialized and works as a counter of
* the free bytes in the queue.
* @note The callback is invoked from within the S-Locked system state,
* see @ref system_states.
*
* @param[out] oqp pointer to an @p OutputQueue structure
* @param[in] bp pointer to a memory area allocated as queue buffer
* @param[in] size size of the queue buffer
* @param[in] onfy pointer to a callback function that is invoked when
* data is written to the queue. The value can be @p NULL.
*
* @init
*/
void chOQInit(OutputQueue *oqp, uint8_t *bp, size_t size, qnotify_t onfy) {
queue_init(&oqp->q_waiting);
oqp->q_counter = size;
oqp->q_buffer = oqp->q_rdptr = oqp->q_wrptr = bp;
oqp->q_top = bp + size;
oqp->q_notify = onfy;
}
/**
* @brief Resets an output queue.
* @details All the data in the output queue is erased and lost, any waiting
* thread is resumed with status @p Q_RESET.
* @note A reset operation can be used by a low level driver in order to
* obtain immediate attention from the high level layers.
*
* @param[in] oqp pointer to an @p OutputQueue structure
*
* @iclass
*/
void chOQResetI(OutputQueue *oqp) {
chDbgCheckClassI();
oqp->q_rdptr = oqp->q_wrptr = oqp->q_buffer;
oqp->q_counter = chQSizeI(oqp);
while (notempty(&oqp->q_waiting))
chSchReadyI(fifo_remove(&oqp->q_waiting))->p_u.rdymsg = Q_RESET;
}
/**
* @brief Output queue write with timeout.
* @details This function writes a byte value to an output queue. If the queue
* is full then the calling thread is suspended until there is space
* in the queue or a timeout occurs.
* @note The callback is invoked after writing the character into the
* buffer.
*
* @param[in] oqp pointer to an @p OutputQueue structure
* @param[in] b the byte value to be written in the queue
* @param[in] time 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 Q_OK if the operation succeeded.
* @retval Q_TIMEOUT if the specified time expired.
* @retval Q_RESET if the queue has been reset.
*
* @api
*/
msg_t chOQPutTimeout(OutputQueue *oqp, uint8_t b, systime_t time) {
chSysLock();
while (chOQIsFullI(oqp)) {
msg_t msg;
if ((msg = qwait((GenericQueue *)oqp, time)) < Q_OK) {
chSysUnlock();
return msg;
}
}
oqp->q_counter--;
*oqp->q_wrptr++ = b;
if (oqp->q_wrptr >= oqp->q_top)
oqp->q_wrptr = oqp->q_buffer;
if (oqp->q_notify)
oqp->q_notify(oqp);
chSysUnlock();
return Q_OK;
}
/**
* @brief Output queue read.
* @details A byte value is read from the low end of an output queue.
*
* @param[in] oqp pointer to an @p OutputQueue structure
* @return The byte value from the queue.
* @retval Q_EMPTY if the queue is empty.
*
* @iclass
*/
msg_t chOQGetI(OutputQueue *oqp) {
uint8_t b;
chDbgCheckClassI();
if (chOQIsEmptyI(oqp))
return Q_EMPTY;
oqp->q_counter++;
b = *oqp->q_rdptr++;
if (oqp->q_rdptr >= oqp->q_top)
oqp->q_rdptr = oqp->q_buffer;
if (notempty(&oqp->q_waiting))
chSchReadyI(fifo_remove(&oqp->q_waiting))->p_u.rdymsg = Q_OK;
return b;
}
/**
* @brief Output queue write with timeout.
* @details The function writes data from a buffer to an output queue. The
* operation completes when the specified amount of data has been
* transferred or after the specified timeout or if the queue has
* been reset.
* @note The function is not atomic, if you need atomicity it is suggested
* to use a semaphore or a mutex for mutual exclusion.
* @note The callback is invoked after writing each character into the
* buffer.
*
* @param[in] oqp pointer to an @p OutputQueue structure
* @param[out] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred, the
* value 0 is reserved
* @param[in] time 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 number of bytes effectively transferred.
*
* @api
*/
size_t chOQWriteTimeout(OutputQueue *oqp, const uint8_t *bp,
size_t n, systime_t time) {
qnotify_t nfy = oqp->q_notify;
size_t w = 0;
chDbgCheck(n > 0, "chOQWriteTimeout");
chSysLock();
while (TRUE) {
while (chOQIsFullI(oqp)) {
if (qwait((GenericQueue *)oqp, time) != Q_OK) {
chSysUnlock();
return w;
}
}
oqp->q_counter--;
*oqp->q_wrptr++ = *bp++;
if (oqp->q_wrptr >= oqp->q_top)
oqp->q_wrptr = oqp->q_buffer;
if (nfy)
nfy(oqp);
chSysUnlock(); /* Gives a preemption chance in a controlled point.*/
w++;
if (--n == 0)
return w;
chSysLock();
}
}
#endif /* CH_USE_QUEUES */
/** @} */