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/*
ChibiOS - Copyright (C) 2006..2016 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; either version 3 of the License, or
(at your option) any later version.
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 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. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Virtual Timers initialization.
* @note Internal use only.
*
* @notapi
*/
void _vt_init(void) {
ch.vtlist.next = (virtual_timer_t *)&ch.vtlist;
ch.vtlist.prev = (virtual_timer_t *)&ch.vtlist;
ch.vtlist.delta = (systime_t)-1;
#if CH_CFG_ST_TIMEDELTA == 0
ch.vtlist.systime = (systime_t)0;
#else /* CH_CFG_ST_TIMEDELTA > 0 */
ch.vtlist.lasttime = (systime_t)0;
#endif /* CH_CFG_ST_TIMEDELTA > 0 */
}
/**
* @brief Enables a 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, systime_t delay,
vtfunc_t vtfunc, void *par) {
virtual_timer_t *p;
systime_t delta;
chDbgCheckClassI();
chDbgCheck((vtp != NULL) && (vtfunc != NULL) && (delay != TIME_IMMEDIATE));
vtp->par = par;
vtp->func = vtfunc;
#if CH_CFG_ST_TIMEDELTA > 0
{
systime_t now = chVTGetSystemTimeX();
/* If the requested delay is lower than the minimum safe delta then it
is raised to the minimum safe value.*/
if (delay < (systime_t)CH_CFG_ST_TIMEDELTA) {
delay = (systime_t)CH_CFG_ST_TIMEDELTA;
}
/* Special case where the timers list is empty.*/
if (&ch.vtlist == (virtual_timers_list_t *)ch.vtlist.next) {
/* The delta list is empty, the current time becomes the new
delta list base time, the timer is inserted.*/
ch.vtlist.lasttime = now;
ch.vtlist.next = vtp;
ch.vtlist.prev = vtp;
vtp->next = (virtual_timer_t *)&ch.vtlist;
vtp->prev = (virtual_timer_t *)&ch.vtlist;
vtp->delta = delay;
/* Being the first element in the list the alarm timer is started.*/
port_timer_start_alarm(ch.vtlist.lasttime + delay);
return;
}
/* Pointer to the first element in the delta list, which is non-empty.*/
p = ch.vtlist.next;
/* Delay as delta from 'lasttime'. Note, it can overflow and the value
becomes lower than 'now'.*/
delta = now - ch.vtlist.lasttime + delay;
if (delta < now - ch.vtlist.lasttime) {
/* Scenario where a very large delay excedeed the numeric range, it
requires a special handling. We need to skip the first element and
adjust the delta to wrap back in the previous numeric range.*/
delta -= p->delta;
p = p->next;
}
else if (delta < p->delta) {
/* A small delay that will become the first element in the delta list
and next deadline.*/
port_timer_set_alarm(ch.vtlist.lasttime + delta);
}
}
#else /* CH_CFG_ST_TIMEDELTA == 0 */
/* Delta is initially equal to the specified delay.*/
delta = delay;
/* Pointer to the first element in the delta list.*/
p = ch.vtlist.next;
#endif /* CH_CFG_ST_TIMEDELTA == 0 */
/* The delta list is scanned in order to find the correct position for
this timer. */
while (p->delta < delta) {
delta -= p->delta;
p = p->next;
}
/* The timer is inserted in the delta list.*/
vtp->next = p;
vtp->prev = vtp->next->prev;
vtp->prev->next = vtp;
p->prev = vtp;
vtp->delta = delta
/* Special case when the timer is in last position in the list, the
value in the header must be restored.*/;
p->delta -= delta;
ch.vtlist.delta = (systime_t)-1;
}
/**
* @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) {
chDbgCheckClassI();
chDbgCheck(vtp != NULL);
chDbgAssert(vtp->func != NULL, "timer not set or already triggered");
#if CH_CFG_ST_TIMEDELTA == 0
/* The delta of the timer is added to the next timer.*/
vtp->next->delta += vtp->delta;
/* Removing the element from the delta list.*/
vtp->prev->next = vtp->next;
vtp->next->prev = vtp->prev;
vtp->func = NULL;
/* The above code changes the value in the header when the removed element
is the last of the list, restoring it.*/
ch.vtlist.delta = (systime_t)-1;
#else /* CH_CFG_ST_TIMEDELTA > 0 */
systime_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 (ch.vtlist.next != vtp) {
/* Removing the element from the delta list.*/
vtp->prev->next = vtp->next;
vtp->next->prev = vtp->prev;
vtp->func = NULL;
/* Adding delta to the next element, if it is not the last one.*/
if (&ch.vtlist != (virtual_timers_list_t *)vtp->next)
vtp->next->delta += vtp->delta;
return;
}
/* Removing the first timer from the list.*/
ch.vtlist.next = vtp->next;
ch.vtlist.next->prev = (virtual_timer_t *)&ch.vtlist;
vtp->func = NULL;
/* If the list become empty then the alarm timer is stopped and done.*/
if (&ch.vtlist == (virtual_timers_list_t *)ch.vtlist.next) {
port_timer_stop_alarm();
return;
}
/* The delta of the removed timer is added to the new first timer.*/
ch.vtlist.next->delta += vtp->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 (ch.vtlist.next->delta == 0) {
return;
}*/
/* Distance in ticks between the last alarm event and current time.*/
nowdelta = chVTGetSystemTimeX() - ch.vtlist.lasttime;
/* If the current time surpassed the time of the next element in list
then the event interrupt is already pending, just return.*/
if (nowdelta >= ch.vtlist.next->delta) {
return;
}
/* Distance from the next scheduled event and now.*/
delta = ch.vtlist.next->delta - nowdelta;
/* Making sure to not schedule an event closer than CH_CFG_ST_TIMEDELTA
ticks from now.*/
if (delta < (systime_t)CH_CFG_ST_TIMEDELTA) {
delta = (systime_t)CH_CFG_ST_TIMEDELTA;
}
port_timer_set_alarm(ch.vtlist.lasttime + nowdelta + delta);
#endif /* CH_CFG_ST_TIMEDELTA > 0 */
}
/** @} */
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