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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012,2013 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 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. */
/*===========================================================================*/
/**
* @brief Virtual timers delta list header.
*/
virtual_timers_list_t vtlist;
/*===========================================================================*/
/* 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) {
vtlist.vt_next = vtlist.vt_prev = (void *)&vtlist;
vtlist.vt_delta = (systime_t)-1;
#if CH_CFG_TIMEDELTA == 0
vtlist.vt_systime = 0;
#else /* CH_CFG_TIMEDELTA > 0 */
vtlist.vt_lasttime = 0;
#endif /* CH_CFG_TIMEDELTA > 0 */
}
/**
* @brief Checks if the current system time is within the specified time
* window.
* @note When start==end then the function returns always true because the
* whole time range is specified.
* @note This function can be called from any context.
*
* @param[in] time the time to be verified
* @param[in] start the start of the time window (inclusive)
* @param[in] end the end of the time window (non inclusive)
* @retval true current time within the specified time window.
* @retval false current time not within the specified time window.
*
* @special
*/
bool chVTIsTimeWithin(systime_t time, systime_t start, systime_t end) {
return end > start ? (time >= start) && (time < end) :
(time >= start) || (time < end);
}
/**
* @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),
"chVTDoSetI");
vtp->vt_par = par;
vtp->vt_func = vtfunc;
p = vtlist.vt_next;
#if CH_CFG_TIMEDELTA > 0 || defined(__DOXYGEN__)
{
systime_t now = port_timer_get_time();
/* If the requested delay is lower than the minimum safe delta then it
is raised to the minimum safe value.*/
if (delay < CH_CFG_TIMEDELTA)
delay = CH_CFG_TIMEDELTA;
if (&vtlist == (virtual_timers_list_t *)p) {
/* The delta list is empty, the current time becomes the new
delta list base time.*/
vtlist.vt_lasttime = now;
port_timer_start_alarm(vtlist.vt_lasttime + delay);
}
else {
/* Now the delay is calculated as delta from the last tick interrupt
time.*/
delay += now - 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(vtlist.vt_lasttime + delay);
}
}
#endif /* CH_CFG_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_prev = (vtp->vt_next = p)->vt_prev;
vtp->vt_prev->vt_next = 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;
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) {
chDbgCheckClassI();
chDbgCheck(vtp != NULL, "chVTDoResetI");
chDbgAssert(vtp->vt_func != NULL,
"chVTDoResetI(), #1",
"timer not set or already triggered");
/* 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 = (vtfunc_t)NULL;
/* The above code changes the value in the header when the removed element
is the last of the list, restoring it.*/
vtlist.vt_delta = (systime_t)-1;
#if CH_CFG_TIMEDELTA > 0 || defined(__DOXYGEN__)
{
if (&vtlist == (virtual_timers_list_t *)vtlist.vt_next) {
/* Just removed the last element in the list, alarm timer stopped.*/
port_timer_stop_alarm();
}
else {
/* The alarm is set to the next element in the delta list.*/
port_timer_set_alarm(vtlist.vt_lasttime + vtlist.vt_next->vt_delta);
}
}
#endif /* CH_CFG_TIMEDELTA > 0 */
}
/** @} */
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