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/*
ChibiOS - Copyright (C) 2006..2015 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.vt_next = (virtual_timer_t *)&ch.vtlist;
ch.vtlist.vt_prev = (virtual_timer_t *)&ch.vtlist;
ch.vtlist.vt_delta = (systime_t)-1;
#if CH_CFG_ST_TIMEDELTA == 0
ch.vtlist.vt_systime = (systime_t)0;
#else /* CH_CFG_ST_TIMEDELTA > 0 */
ch.vtlist.vt_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;
chDbgCheckClassI();
chDbgCheck((vtp != NULL) && (vtfunc != NULL) && (delay != TIME_IMMEDIATE));
vtp->vt_par = par;
vtp->vt_func = vtfunc;
p = ch.vtlist.vt_next;
#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;
}
if (&ch.vtlist == (virtual_timers_list_t *)p) {
/* The delta list is empty, the current time becomes the new
delta list base time.*/
ch.vtlist.vt_lasttime = now;
port_timer_start_alarm(ch.vtlist.vt_lasttime + delay);
}
else {
/* Now the delay is calculated as delta from the last tick interrupt
time.*/
delay += now - ch.vtlist.vt_lasttime;
/* If the specified delay is closer in time than the first element
in the delta list then it becomes the next alarm event in time.*/
if (delay < p->vt_delta) {
port_timer_set_alarm(ch.vtlist.vt_lasttime + delay);
}
}
}
#endif /* CH_CFG_ST_TIMEDELTA > 0 */
/* The delta list is scanned in order to find the correct position for
this timer. */
while (p->vt_delta < delay) {
delay -= p->vt_delta;
p = p->vt_next;
}
/* The timer is inserted in the delta list.*/
vtp->vt_next = p;
vtp->vt_prev = vtp->vt_next->vt_prev;
vtp->vt_prev->vt_next = vtp;
p->vt_prev = vtp;
vtp->vt_delta = delay
/* Special case when the timer is in last position in the list, the
value in the header must be restored.*/;
p->vt_delta -= delay;
ch.vtlist.vt_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) {
#if CH_CFG_ST_TIMEDELTA > 0
virtual_timer_t *first;
#endif
chDbgCheckClassI();
chDbgCheck(vtp != NULL);
chDbgAssert(vtp->vt_func != NULL, "timer not set or already triggered");
/* Checking if the element to be removed was the first in the list.*/
#if CH_CFG_ST_TIMEDELTA > 0
first = ch.vtlist.vt_next;
#endif
/* Removing the element from the delta list.*/
vtp->vt_next->vt_delta += vtp->vt_delta;
vtp->vt_prev->vt_next = vtp->vt_next;
vtp->vt_next->vt_prev = vtp->vt_prev;
vtp->vt_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.vt_delta = (systime_t)-1;
#if CH_CFG_ST_TIMEDELTA > 0
{
systime_t nowdelta, delta;
/* Just removed the last element in the list, alarm timer stopped and
return.*/
if (&ch.vtlist == (virtual_timers_list_t *)ch.vtlist.vt_next) {
port_timer_stop_alarm();
return;
}
/* If the removed element was not the first one then just return, the
alarm is already set to the first element.*/
if (vtp != first) {
return;
}
/* If the new first element has a delta of zero then the alarm is not
modified, the already programmed alarm will serve it.*/
if (ch.vtlist.vt_next->vt_delta == 0) {
return;
}
/* Distance in ticks between the last alarm event and current time.*/
nowdelta = chVTGetSystemTimeX() - ch.vtlist.vt_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.vt_next->vt_delta) {
return;
}
/* Distance from the next scheduled event and now.*/
delta = ch.vtlist.vt_next->vt_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.vt_lasttime + nowdelta + delta);
}
#endif /* CH_CFG_ST_TIMEDELTA > 0 */
}
/** @} */
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