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ChibiOS/os/rt/src/chvt.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 rt/src/chvt.c
* @brief Time and Virtual Timers module code.
*
* @addtogroup time
* @details Time and Virtual Timers related APIs and services.
* @{
*/
#include "ch.h"
/*===========================================================================*/
/* Module local definitions. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local types. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local functions. */
/*===========================================================================*/
/**
* @brief List empty check.
*
* @param[in] dlhp pointer to the delta list header
*
* @notapi
*/
static inline bool is_vtlist_empty(delta_list_t *dlhp) {
return (bool)(dlhp == dlhp->next);
}
#if (CH_CFG_ST_TIMEDELTA > 0) || defined(__DOXYGEN__)
/**
* @brief Last timer in the list check.
*
* @param[in] dlhp pointer to the delta list header
* @param[in] dlp pointer to the delta list element
*
* @notapi
*/
static inline bool is_last_timer(delta_list_t *dlhp, delta_list_t *dlp) {
return (bool)(dlp->next == dlhp);
}
/**
* @brief Fist timer in the list check.
*
* @param[in] dlhp pointer to the delta list header
* @param[in] dlp pointer to the delta list element
*
* @notapi
*/
static inline bool is_first_timer(delta_list_t *dlhp, delta_list_t *dlp) {
return (bool)(dlhp->next == dlp);
}
/**
* @brief Timer check.
*
* @param[in] dlhp pointer to the delta list header
* @param[in] dlp pointer to the delta list element
*
* @notapi
*/
static inline bool is_timer(delta_list_t *dlhp, delta_list_t *dlp) {
return (bool)(dlp != dlhp);
}
/**
* @brief Delta list compression.
*
* @param[in] vtlp pointer to the delta list to be compressed
* @param[in] deltanow interval to be compacted starting from "lasttime"
*
* @notapi
*/
static void vt_list_compress(virtual_timers_list_t *vtlp,
sysinterval_t deltanow) {
delta_list_t *dlp = vtlp->dlist.next;
/* The loop is bounded because the delta list header has the delta field
set to (sysinterval_t)-1 which is larger than all deltas.*/
while (dlp->delta < deltanow) {
deltanow -= dlp->delta;
dlp->delta = (sysinterval_t)0;
dlp = dlp->next;
}
vtlp->lasttime = vtlp->lasttime + deltanow;
/* Adjusting next timer in the list, if any.*/
if (is_timer(&vtlp->dlist, dlp)) {
dlp->delta -= deltanow;
}
}
#endif
/**
* @brief Enqueues a virtual timer in a virtual timers list.
*/
static void vt_enqueue(virtual_timers_list_t *vtlp,
virtual_timer_t *vtp,
systime_t now,
sysinterval_t delay) {
delta_list_t *dlp;
sysinterval_t delta;
#if CH_CFG_ST_TIMEDELTA > 0
{
sysinterval_t deltanow;
/* If the requested delay is lower than the minimum safe delta then it
is raised to the minimum safe value.*/
if (delay < (sysinterval_t)CH_CFG_ST_TIMEDELTA) {
delay = (sysinterval_t)CH_CFG_ST_TIMEDELTA;
}
/* Special case where the timers list is empty.*/
if (is_vtlist_empty(&vtlp->dlist)) {
/* The delta list is empty, the current time becomes the new
delta list base time, the timer is inserted.*/
vtlp->lasttime = now;
vtlp->dlist.next = &vtp->dlist;
vtlp->dlist.prev = &vtp->dlist;
vtp->dlist.next = &vtlp->dlist;
vtp->dlist.prev = &vtlp->dlist;
vtp->dlist.delta = delay;
#if CH_CFG_INTERVALS_SIZE > CH_CFG_ST_RESOLUTION
/* The delta could be too large for the physical timer to handle.*/
if (delay > (sysinterval_t)TIME_MAX_SYSTIME) {
delay = (sysinterval_t)TIME_MAX_SYSTIME;
}
#endif
/* Being the first element in the list the alarm timer is started.*/
port_timer_start_alarm(chTimeAddX(vtlp->lasttime, delay));
return;
}
/* Delay as delta from 'lasttime'. Note, it can overflow and the value
becomes lower than 'deltanow'.*/
deltanow = chTimeDiffX(vtlp->lasttime, now);
delta = deltanow + delay;
/* Scenario where a very large delay exceeded the numeric range, it
requires a special handling, the compression procedure.*/
if (delta < deltanow) {
vt_list_compress(vtlp, deltanow);
delta -= deltanow;
}
else if (delta < vtlp->dlist.next->delta) {
sysinterval_t deadline_delta;
/* A small delay that will become the first element in the delta list
and next deadline.*/
deadline_delta = delta;
#if CH_CFG_INTERVALS_SIZE > CH_CFG_ST_RESOLUTION
/* The delta could be too large for the physical timer to handle.*/
if (deadline_delta > (sysinterval_t)TIME_MAX_SYSTIME) {
deadline_delta = (sysinterval_t)TIME_MAX_SYSTIME;
}
#endif
port_timer_set_alarm(chTimeAddX(vtlp->lasttime, deadline_delta));
}
}
#else /* CH_CFG_ST_TIMEDELTA == 0 */
/* Delta is initially equal to the specified delay.*/
delta = delay;
#endif /* CH_CFG_ST_TIMEDELTA == 0 */
/* The delta list is scanned in order to find the correct position for
this timer. */
dlp = vtlp->dlist.next;
while (dlp->delta < delta) {
/* Debug assert if the timer is already in the list.*/
chDbgAssert(dlp != &vtp->dlist, "timer already armed");
delta -= dlp->delta;
dlp = dlp->next;
}
/* The timer is inserted in the delta list.*/
vtp->dlist.next = dlp;
vtp->dlist.prev = vtp->dlist.next->prev;
vtp->dlist.prev->next = &vtp->dlist;
dlp->prev = &vtp->dlist;
vtp->dlist.delta = delta;
/* Calculate new delta for the following entry.*/
dlp->delta -= delta;
/* Special case when the timer is in last position in the list, the
value in the header must be restored.*/
vtlp->dlist.delta = (sysinterval_t)-1;
}
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Enables a one-shot virtual timer.
* @details The timer is enabled and programmed to trigger after the delay
* specified as parameter.
* @pre The timer must not be already armed before calling this function.
* @note The callback function is invoked from interrupt context.
*
* @param[out] vtp the @p virtual_timer_t structure pointer
* @param[in] delay the number of ticks before the operation timeouts, the
* special values are handled as follow:
* - @a TIME_INFINITE is allowed but interpreted as a
* normal time specification.
* - @a TIME_IMMEDIATE this value is not allowed.
* .
* @param[in] vtfunc the timer callback function. After invoking the
* callback the timer is disabled and the structure can
* be disposed or reused.
* @param[in] par a parameter that will be passed to the callback
* function
*
* @iclass
*/
void chVTDoSetI(virtual_timer_t *vtp, sysinterval_t delay,
vtfunc_t vtfunc, void *par) {
virtual_timers_list_t *vtlp = &currcore->vtlist;
systime_t now;
chDbgCheckClassI();
chDbgCheck((vtp != NULL) && (vtfunc != NULL) && (delay != TIME_IMMEDIATE));
/* Current system time.*/
now = chVTGetSystemTimeX();
/* Timer initialization.*/
vtp->par = par;
vtp->func = vtfunc;
vtp->last = now;
vtp->reload = (sysinterval_t)0;
/* Inserting the timer in the delta list.*/
vt_enqueue(vtlp, vtp, vtp->last, delay);
}
/**
* @brief Enables a continuous virtual timer.
* @details The timer is enabled and programmed to trigger after the delay
* specified as parameter.
* @pre The timer must not be already armed before calling this function.
* @note The callback function is invoked from interrupt context.
*
* @param[out] vtp the @p virtual_timer_t structure pointer
* @param[in] delay the number of ticks before the operation timeouts, the
* special values are handled as follow:
* - @a TIME_INFINITE is allowed but interpreted as a
* normal time specification.
* - @a TIME_IMMEDIATE this value is not allowed.
* .
* @param[in] vtfunc the timer callback function. After invoking the
* callback the timer is disabled and the structure can
* be disposed or reused.
* @param[in] par a parameter that will be passed to the callback
* function
*
* @iclass
*/
void chVTDoSetContinuousI(virtual_timer_t *vtp, sysinterval_t delay,
vtfunc_t vtfunc, void *par) {
virtual_timers_list_t *vtlp = &currcore->vtlist;
systime_t now;
chDbgCheckClassI();
chDbgCheck((vtp != NULL) && (vtfunc != NULL) && (delay != TIME_IMMEDIATE));
/* Current system time.*/
now = chVTGetSystemTimeX();
/* Timer initialization.*/
vtp->par = par;
vtp->func = vtfunc;
vtp->last = now;
vtp->reload = delay;
/* Inserting the timer in the delta list.*/
vt_enqueue(vtlp, vtp, vtp->last, delay);
}
/**
* @brief Disables a Virtual Timer.
* @pre The timer must be in armed state before calling this function.
*
* @param[in] vtp the @p virtual_timer_t structure pointer
*
* @iclass
*/
void chVTDoResetI(virtual_timer_t *vtp) {
virtual_timers_list_t *vtlp = &currcore->vtlist;
chDbgCheckClassI();
chDbgCheck(vtp != NULL);
chDbgAssert(chVTIsArmedI(vtp), "timer not armed");
#if CH_CFG_ST_TIMEDELTA == 0
/* The delta of the timer is added to the next timer.*/
vtp->dlist.next->delta += vtp->dlist.delta;
/* Removing the element from the delta list, marking it as not armed.*/
vtp->dlist.prev->next = vtp->dlist.next;
vtp->dlist.next->prev = vtp->dlist.prev;
vtp->dlist.next = NULL;
/* The above code changes the value in the header when the removed element
is the last of the list, restoring it.*/
vtlp->dlist.delta = (sysinterval_t)-1;
#else /* CH_CFG_ST_TIMEDELTA > 0 */
sysinterval_t nowdelta, delta;
/* If the timer is not the first of the list then it is simply unlinked
else the operation is more complex.*/
if (!is_first_timer(&vtlp->dlist, &vtp->dlist)) {
/* Removing the element from the delta list.*/
vtp->dlist.prev->next = vtp->dlist.next;
vtp->dlist.next->prev = vtp->dlist.prev;
/* Adding delta to the next element, if it is not the last one.*/
if (is_timer(&vtlp->dlist, vtp->dlist.next))
vtp->dlist.next->delta += vtp->dlist.delta;
/* Marking timer as not armed.*/
vtp->dlist.next = NULL;
return;
}
/* Removing the first timer from the list, marking it as not armed.*/
vtlp->dlist.next = vtp->dlist.next;
vtlp->dlist.next->prev = &vtlp->dlist;
vtp->dlist.next = NULL;
/* If the list become empty then the alarm timer is stopped and done.*/
if (is_vtlist_empty(&vtlp->dlist)) {
port_timer_stop_alarm();
return;
}
/* The delta of the removed timer is added to the new first timer.*/
vtlp->dlist.next->delta += vtp->dlist.delta;
/* If the new first timer has a delta of zero then the alarm is not
modified, the already programmed alarm will serve it.*/
/* if (vtlp->dlist.next->delta == 0) {
return;
}*/
/* Distance in ticks between the last alarm event and current time.*/
nowdelta = chTimeDiffX(vtlp->lasttime, chVTGetSystemTimeX());
/* If the current time surpassed the time of the next element in list
then the event interrupt is already pending, just return.*/
if (nowdelta >= vtlp->dlist.next->delta) {
return;
}
/* Distance from the next scheduled event and now.*/
delta = vtlp->dlist.next->delta - nowdelta;
/* Making sure to not schedule an event closer than CH_CFG_ST_TIMEDELTA
ticks from now.*/
if (delta < (sysinterval_t)CH_CFG_ST_TIMEDELTA) {
delta = nowdelta + (sysinterval_t)CH_CFG_ST_TIMEDELTA;
}
else {
delta = nowdelta + delta;
#if CH_CFG_INTERVALS_SIZE > CH_CFG_ST_RESOLUTION
/* The delta could be too large for the physical timer to handle.*/
if (delta > (sysinterval_t)TIME_MAX_SYSTIME) {
delta = (sysinterval_t)TIME_MAX_SYSTIME;
}
#endif
}
port_timer_set_alarm(chTimeAddX(vtlp->lasttime, delta));
#endif /* CH_CFG_ST_TIMEDELTA > 0 */
}
/**
* @brief Virtual timers ticker.
* @note The system lock is released before entering the callback and
* re-acquired immediately after. It is callback's responsibility
* to acquire the lock if needed. This is done in order to reduce
* interrupts jitter when many timers are in use.
*
* @iclass
*/
void chVTDoTickI(void) {
virtual_timers_list_t *vtlp = &currcore->vtlist;
chDbgCheckClassI();
#if CH_CFG_ST_TIMEDELTA == 0
vtlp->systime++;
if (!is_vtlist_empty(&vtlp->dlist)) {
/* The list is not empty, processing elements on top.*/
--vtlp->dlist.next->delta;
while (vtlp->dlist.next->delta == (sysinterval_t)0) {
virtual_timer_t *vtp;
/* Triggered timer.*/
vtp = (virtual_timer_t *)vtlp->dlist.next;
/* Removing the element from the delta list, marking it as not armed.*/
vtp->dlist.next->prev = &vtlp->dlist;
vtlp->dlist.next = vtp->dlist.next;
vtp->dlist.next = NULL;
chSysUnlockFromISR();
vtp->func(vtp->par);
chSysLockFromISR();
}
}
#else /* CH_CFG_ST_TIMEDELTA > 0 */
delta_list_t *dlp;
sysinterval_t delta, nowdelta;
systime_t now = chVTGetSystemTimeX();
/* Looping through timers.*/
dlp = vtlp->dlist.next;
while (true) {
/* Delta between current time and last execution time.*/
nowdelta = chTimeDiffX(vtlp->lasttime, now);
/* The list scan is limited by the timers header having
"vtlp->dlist.delta == (sysinterval_t)-1" which is
greater than all deltas.*/
if (nowdelta < dlp->delta) {
break;
}
/* Consuming all timers between "vtp->lasttime" and now.*/
do {
virtual_timer_t *vtp = (virtual_timer_t *)dlp;
/* The "last time" becomes this timer's expiration time.*/
vtlp->lasttime += dlp->delta;
nowdelta -= dlp->delta;
/* Removing the timer from the list, marking it as not armed.*/
dlp->next->prev = &vtlp->dlist;
vtlp->dlist.next = dlp->next;
dlp->next = NULL;
/* If the list becomes empty then the timer is stopped.*/
if (is_vtlist_empty(&vtlp->dlist)) {
port_timer_stop_alarm();
}
/* Now "last" marks the current deadline based on the stored
reload value. It is done before calling the callback because
the reload value could change. Note that "reload" could be
zero, no harm.*/
vtp->last = chTimeAddX(vtp->last, vtp->reload);
/* The callback is invoked outside the kernel critical zone.*/
chSysUnlockFromISR();
vtp->func(vtp->par);
chSysLockFromISR();
/* Getting again the system time after executing the callback in
order to reduce error.*/
now = chVTGetSystemTimeX();
/* If a reload is defined the timer needs to be restarted.*/
if (vtp->reload > (sysinterval_t)0) {
sysinterval_t skipped_delta;
/* Calculating how much the real current time skipped past the
hypothetical current deadline.*/
skipped_delta = chTimeDiffX(vtp->last, now);
chDbgAssert(skipped_delta < vtp->reload, "skipped deadline");
/* Enqueuing the timer again using the calculated delta.*/
vt_enqueue(vtlp, vtp, now, vtp->reload - skipped_delta);
}
/* Next element in the list.*/
dlp = vtlp->dlist.next;
}
while (dlp->delta <= nowdelta);
}
/* If the list is empty, nothing else to do.*/
if (is_vtlist_empty(&vtlp->dlist)) {
return;
}
/* The "unprocessed nowdelta" time slice is added to "last time"
and subtracted to next timer's delta.*/
// vtlp->lasttime += nowdelta;
vtlp->lasttime = chTimeAddX(vtlp->lasttime, nowdelta);
vtlp->dlist.next->delta -= nowdelta;
/* Recalculating the next alarm time.*/
delta = dlp->delta - chTimeDiffX(vtlp->lasttime, now);
if (delta < (sysinterval_t)CH_CFG_ST_TIMEDELTA) {
delta = (sysinterval_t)CH_CFG_ST_TIMEDELTA;
}
#if CH_CFG_INTERVALS_SIZE > CH_CFG_ST_RESOLUTION
/* The delta could be too large for the physical timer to handle.*/
else if (delta > (sysinterval_t)TIME_MAX_SYSTIME) {
delta = (sysinterval_t)TIME_MAX_SYSTIME;
}
#endif
port_timer_set_alarm(chTimeAddX(now, delta));
chDbgAssert(chTimeDiffX(vtlp->lasttime, chVTGetSystemTimeX()) <=
chTimeDiffX(vtlp->lasttime, chTimeAddX(now, delta)),
"exceeding delta");
#endif /* CH_CFG_ST_TIMEDELTA > 0 */
}
#if (CH_CFG_USE_TIMESTAMP == TRUE) || defined(__DOXYGEN__)
/**
* @brief Generates a monotonic time stamp.
* @details This function generates a monotonic time stamp synchronized with
* the system time. The time stamp has the same resolution of
* system time.
* @note There is an assumption, this function must be called at
* least once before the system time wraps back to zero or
* synchronization is lost. You may use a periodic virtual timer with
* a very large interval in order to keep time stamps synchronized
* by calling this function.
*
* @return The time stamp.
*
* @iclass
*/
systimestamp_t chVTGetTimeStampI(void) {
os_instance_t * oip = currcore;
systimestamp_t last, stamp;
systime_t now;
chDbgCheckClassI();
/* Current system time.*/
now = chVTGetSystemTimeX();
/* Last time stamp generated.*/
last = oip->vtlist.laststamp;
/* Interval between the last time stamp and current time used for a new
time stamp. Note that this fails if the interval is larger than a
systime_t type.*/
stamp = last + (systimestamp_t)chTimeDiffX((systime_t)last, now);
chDbgAssert(oip->vtlist.laststamp <= stamp, "wrapped");
/* Storing the new stamp.*/
oip->vtlist.laststamp = stamp;
return stamp;
}
/**
* @brief Resets and re-synchronizes the time stamps monotonic counter.
*
* @iclass
*/
void chVTResetTimeStampI(void) {
chDbgCheckClassI();
currcore->vtlist.laststamp = (systimestamp_t)chVTGetSystemTimeX();
}
#endif /* CH_CFG_USE_TIMESTAMP == TRUE */
/** @} */
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