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ChibiOS/os/oslib/src/chpipes.c

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/*
ChibiOS - Copyright (C) 2006,2007,2008,2009,2010,2011,2012,2013,2014,
2015,2016,2017,2018,2019,2020,2021 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 version 3 of the License.
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 oslib/src/chpipes.c
* @brief Pipes code.
* @details Byte pipes.
* <h2>Operation mode</h2>
* A pipe is an asynchronous communication mechanism.<br>
* Operations defined for mailboxes:
* - <b>Write</b>: Writes a buffer of data in the pipe in FIFO order.
* - <b>Read</b>: A buffer of data is read from the read and removed.
* - <b>Reset</b>: The pipe is emptied and all the stored data
* is lost.
* .
* @pre In order to use the pipes APIs the @p CH_CFG_USE_PIPES
* option must be enabled in @p chconf.h.
* @note Compatible with RT and NIL.
*
* @addtogroup oslib_pipes
* @{
*/
#include <string.h>
#include "ch.h"
#if (CH_CFG_USE_PIPES == TRUE) || defined(__DOXYGEN__)
/*===========================================================================*/
/* Module local definitions. */
/*===========================================================================*/
/*
* Defaults on the best synchronization mechanism available.
*/
#if (CH_CFG_USE_MUTEXES == TRUE) || defined(__DOXYGEN__)
#define PC_INIT(p) chMtxObjectInit(&(p)->cmtx)
#define PC_LOCK(p) chMtxLock(&(p)->cmtx)
#define PC_UNLOCK(p) chMtxUnlock(&(p)->cmtx)
#define PW_INIT(p) chMtxObjectInit(&(p)->wmtx)
#define PW_LOCK(p) chMtxLock(&(p)->wmtx)
#define PW_UNLOCK(p) chMtxUnlock(&(p)->wmtx)
#define PR_INIT(p) chMtxObjectInit(&(p)->rmtx)
#define PR_LOCK(p) chMtxLock(&(p)->rmtx)
#define PR_UNLOCK(p) chMtxUnlock(&(p)->rmtx)
#else
#define PC_INIT(p) chSemObjectInit(&(p)->csem, (cnt_t)1)
#define PC_LOCK(p) (void) chSemWait(&(p)->csem)
#define PC_UNLOCK(p) chSemSignal(&(p)->csem)
#define PW_INIT(p) chSemObjectInit(&(p)->wsem, (cnt_t)1)
#define PW_LOCK(p) (void) chSemWait(&(p)->wsem)
#define PW_UNLOCK(p) chSemSignal(&(p)->wsem)
#define PR_INIT(p) chSemObjectInit(&(p)->rsem, (cnt_t)1)
#define PR_LOCK(p) (void) chSemWait(&(p)->rsem)
#define PR_UNLOCK(p) chSemSignal(&(p)->rsem)
#endif
/*===========================================================================*/
/* Module exported variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local types. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local functions. */
/*===========================================================================*/
/**
* @brief Non-blocking pipe write.
* @details The function writes data from a buffer to a pipe. The
* operation completes when the specified amount of data has been
* transferred or when the pipe buffer has been filled.
*
* @param[in] pp the pointer to an initialized @p pipe_t object
* @param[in] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred, the
* value 0 is reserved
* @return The number of bytes effectively transferred.
*
* @notapi
*/
static size_t pipe_write(pipe_t *pp, const uint8_t *bp, size_t n) {
size_t s1, s2;
PC_LOCK(pp);
/* Number of bytes that can be written in a single atomic operation.*/
if (n > chPipeGetFreeCount(pp)) {
n = chPipeGetFreeCount(pp);
}
pp->cnt += n;
/* Number of bytes before buffer limit.*/
/*lint -save -e9033 [10.8] Checked to be safe.*/
s1 = (size_t)(pp->top - pp->wrptr);
/*lint -restore*/
if (n < s1) {
memcpy((void *)pp->wrptr, (const void *)bp, n);
pp->wrptr += n;
}
else if (n > s1) {
memcpy((void *)pp->wrptr, (const void *)bp, s1);
bp += s1;
s2 = n - s1;
memcpy((void *)pp->buffer, (const void *)bp, s2);
pp->wrptr = pp->buffer + s2;
}
else {
memcpy((void *)pp->wrptr, (const void *)bp, n);
pp->wrptr = pp->buffer;
}
PC_UNLOCK(pp);
return n;
}
/**
* @brief Non-blocking pipe read.
* @details The function reads data from a pipe into a buffer. The
* operation completes when the specified amount of data has been
* transferred or when the pipe buffer has been emptied.
*
* @param[in] pp the pointer to an initialized @p pipe_t object
* @param[out] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred, the
* value 0 is reserved
* @return The number of bytes effectively transferred.
*
* @notapi
*/
static size_t pipe_read(pipe_t *pp, uint8_t *bp, size_t n) {
size_t s1, s2;
PC_LOCK(pp);
/* Number of bytes that can be read in a single atomic operation.*/
if (n > chPipeGetUsedCount(pp)) {
n = chPipeGetUsedCount(pp);
}
pp->cnt -= n;
/* Number of bytes before buffer limit.*/
/*lint -save -e9033 [10.8] Checked to be safe.*/
s1 = (size_t)(pp->top - pp->rdptr);
/*lint -restore*/
if (n < s1) {
memcpy((void *)bp, (void *)pp->rdptr, n);
pp->rdptr += n;
}
else if (n > s1) {
memcpy((void *)bp, (void *)pp->rdptr, s1);
bp += s1;
s2 = n - s1;
memcpy((void *)bp, (void *)pp->buffer, s2);
pp->rdptr = pp->buffer + s2;
}
else {
memcpy((void *)bp, (void *)pp->rdptr, n);
pp->rdptr = pp->buffer;
}
PC_UNLOCK(pp);
return n;
}
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Initializes a @p mailbox_t object.
*
* @param[out] pp the pointer to the @p pipe_t structure to be
* initialized
* @param[in] buf pointer to the pipe buffer as an array of @p uint8_t
* @param[in] n number of elements in the buffer array
*
* @init
*/
void chPipeObjectInit(pipe_t *pp, uint8_t *buf, size_t n) {
chDbgCheck((pp != NULL) && (buf != NULL) && (n > (size_t)0));
pp->buffer = buf;
pp->rdptr = buf;
pp->wrptr = buf;
pp->top = &buf[n];
pp->cnt = (size_t)0;
pp->reset = false;
pp->wtr = NULL;
pp->rtr = NULL;
PC_INIT(pp);
PW_INIT(pp);
PR_INIT(pp);
}
/**
* @brief Resets a @p pipe_t object.
* @details All the waiting threads are resumed with status @p MSG_RESET and
* the queued data is lost.
* @post The pipe is in reset state, all operations will fail and
* return @p MSG_RESET until the mailbox is enabled again using
* @p chPipeResumeX().
*
* @param[in] pp the pointer to an initialized @p pipe_t object
*
* @api
*/
void chPipeReset(pipe_t *pp) {
chDbgCheck(pp != NULL);
PC_LOCK(pp);
pp->wrptr = pp->buffer;
pp->rdptr = pp->buffer;
pp->cnt = (size_t)0;
pp->reset = true;
chSysLock();
chThdResumeI(&pp->wtr, MSG_RESET);
chThdResumeI(&pp->rtr, MSG_RESET);
chSchRescheduleS();
chSysUnlock();
PC_UNLOCK(pp);
}
/**
* @brief Pipe write with timeout.
* @details The function writes data from a buffer to a pipe. The
* operation completes when the specified amount of data has been
* transferred or after the specified timeout or if the pipe has
* been reset.
*
* @param[in] pp the pointer to an initialized @p pipe_t object
* @param[in] bp pointer to the data buffer
* @param[in] n the number of bytes to be written, the value 0 is
* reserved
* @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 number of bytes effectively transferred. A number
* lower than @p n means that a timeout occurred or the
* pipe went in reset state.
*
* @api
*/
size_t chPipeWriteTimeout(pipe_t *pp, const uint8_t *bp,
size_t n, sysinterval_t timeout) {
size_t max = n;
chDbgCheck(n > 0U);
/* If the pipe is in reset state then returns immediately.*/
if (pp->reset) {
return (size_t)0;
}
PW_LOCK(pp);
while (n > 0U) {
size_t done;
done = pipe_write(pp, bp, n);
if (done == (size_t)0) {
msg_t msg;
chSysLock();
msg = chThdSuspendTimeoutS(&pp->wtr, timeout);
chSysUnlock();
/* Anything except MSG_OK causes the operation to stop.*/
if (msg != MSG_OK) {
break;
}
}
else {
n -= done;
bp += done;
/* Resuming the reader, if present.*/
chThdResume(&pp->rtr, MSG_OK);
}
}
PW_UNLOCK(pp);
return max - n;
}
/**
* @brief Pipe read with timeout.
* @details The function reads data from a pipe into a buffer. The
* operation completes when the specified amount of data has been
* transferred or after the specified timeout or if the pipe has
* been reset.
*
* @param[in] pp the pointer to an initialized @p pipe_t object
* @param[out] bp pointer to the data buffer
* @param[in] n the number of bytes to be read, the value 0 is
* reserved
* @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 number of bytes effectively transferred. A number
* lower than @p n means that a timeout occurred or the
* pipe went in reset state.
*
* @api
*/
size_t chPipeReadTimeout(pipe_t *pp, uint8_t *bp,
size_t n, sysinterval_t timeout) {
size_t max = n;
chDbgCheck(n > 0U);
/* If the pipe is in reset state then returns immediately.*/
if (pp->reset) {
return (size_t)0;
}
PR_LOCK(pp);
while (n > 0U) {
size_t done;
done = pipe_read(pp, bp, n);
if (done == (size_t)0) {
msg_t msg;
chSysLock();
msg = chThdSuspendTimeoutS(&pp->rtr, timeout);
chSysUnlock();
/* Anything except MSG_OK causes the operation to stop.*/
if (msg != MSG_OK) {
break;
}
}
else {
n -= done;
bp += done;
/* Resuming the writer, if present.*/
chThdResume(&pp->wtr, MSG_OK);
}
}
PR_UNLOCK(pp);
return max - n;
}
#endif /* CH_CFG_USE_PIPES == TRUE */
/** @} */
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