chvt.c
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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 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/>.
---
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes ChibiOS/RT, without being obliged to provide
the source code for any proprietary components. See the file exception.txt
for full details of how and when the exception can be applied.
*/
/**
* @file chvt.c
* @brief Time and Virtual Timers related code.
*
* @addtogroup time
* @details Time and Virtual Timers related APIs and services.
* @{
*/
#include "ch.h"
/**
* @brief Virtual timers delta list header.
*/
VTList vtlist;
/**
* @brief Virtual Timers initialization.
* @note Internal use only.
*
* @notapi
*/
void _vt_init(void) {
vtlist.vt_next = vtlist.vt_prev = (void *)&vtlist;
vtlist.vt_time = (systime_t)-1;
vtlist.vt_systime = 0;
}
/**
* @brief Enables a virtual timer.
* @note The associated function is invoked by an interrupt handler within
* the I-Locked state, see @ref system_states.
*
* @param[out] vtp the @p VirtualTimer structure pointer
* @param[in] time 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 chVTSetI(VirtualTimer *vtp, systime_t time, vtfunc_t vtfunc, void *par) {
VirtualTimer *p;
chDbgCheckClassI();
chDbgCheck((vtp != NULL) && (vtfunc != NULL) && (time != TIME_IMMEDIATE),
"chVTSetI");
vtp->vt_par = par;
vtp->vt_func = vtfunc;
p = vtlist.vt_next;
while (p->vt_time < time) {
time -= p->vt_time;
p = p->vt_next;
}
vtp->vt_prev = (vtp->vt_next = p)->vt_prev;
vtp->vt_prev->vt_next = p->vt_prev = vtp;
vtp->vt_time = time;
if (p != (void *)&vtlist)
p->vt_time -= time;
}
/**
* @brief Disables a Virtual Timer.
* @note The timer MUST be active when this function is invoked.
*
* @param[in] vtp the @p VirtualTimer structure pointer
*
* @iclass
*/
void chVTResetI(VirtualTimer *vtp) {
chDbgCheckClassI();
chDbgCheck(vtp != NULL, "chVTResetI");
chDbgAssert(vtp->vt_func != NULL,
"chVTResetI(), #1",
"timer not set or already triggered");
if (vtp->vt_next != (void *)&vtlist)
vtp->vt_next->vt_time += vtp->vt_time;
vtp->vt_prev->vt_next = vtp->vt_next;
vtp->vt_next->vt_prev = vtp->vt_prev;
vtp->vt_func = (vtfunc_t)NULL;
}
/**
* @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.
*
* @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.
*
* @api
*/
bool_t chTimeIsWithin(systime_t start, systime_t end) {
systime_t time = chTimeNow();
return end > start ? (time >= start) && (time < end) :
(time >= start) || (time < end);
}
/** @} */