89 lines
3.5 KiB
C
89 lines
3.5 KiB
C
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/* Watchdog timer management. These functions in this file provide a
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* convenient interface to the timers library that manages a list of
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* watchdog timers. All details of scheduling an alarm at the CLOCK task
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* are hidden behind this interface.
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*
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* The entry points into this file are:
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* init_timer: initialize a timer structure
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* set_timer: reset and existing or set a new watchdog timer
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* cancel_timer: remove a timer from the list of timers
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* expire_timers: check for expired timers and run watchdog functions
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*
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*/
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#include "syslib.h"
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#include <timers.h>
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PRIVATE timer_t *timers = NULL;
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PRIVATE int expiring = 0;
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/*===========================================================================*
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* init_timer *
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*===========================================================================*/
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PUBLIC void init_timer(timer_t *tp)
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{
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tmr_inittimer(tp);
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}
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/*===========================================================================*
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* set_timer *
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*===========================================================================*/
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PUBLIC void set_timer(timer_t *tp, int ticks, tmr_func_t watchdog, int arg)
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{
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int r;
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clock_t now, prev_time = 0, next_time;
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if ((r = getuptime(&now)) != OK)
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panic("set_timer: couldn't get uptime");
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/* Set timer argument and add timer to the list. */
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tmr_arg(tp)->ta_int = arg;
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prev_time = tmrs_settimer(&timers, tp, now+ticks, watchdog, &next_time);
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/* Reschedule our synchronous alarm if necessary. */
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if (expiring == 0 && (! prev_time || prev_time > next_time)) {
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if (sys_setalarm(next_time, 1) != OK)
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panic("set_timer: couldn't set alarm");
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}
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}
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/*===========================================================================*
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* cancel_timer *
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*===========================================================================*/
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PUBLIC void cancel_timer(timer_t *tp)
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{
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clock_t next_time, prev_time;
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prev_time = tmrs_clrtimer(&timers, tp, &next_time);
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/* If the earliest timer has been removed, we have to set the alarm to
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* the next timer, or cancel the alarm altogether if the last timer
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* has been cancelled (next_time will be 0 then).
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*/
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if (expiring == 0 && (prev_time < next_time || ! next_time)) {
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if (sys_setalarm(next_time, 1) != OK)
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panic("cancel_timer: couldn't set alarm");
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}
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}
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/*===========================================================================*
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* expire_timers *
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*===========================================================================*/
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PUBLIC void expire_timers(clock_t now)
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{
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clock_t next_time;
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/* Check for expired timers. Use a global variable to indicate that
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* watchdog functions are called, so that sys_setalarm() isn't called
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* more often than necessary when set_timer or cancel_timer are called
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* from these watchdog functions. */
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expiring = 1;
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tmrs_exptimers(&timers, now, &next_time);
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expiring = 0;
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/* Reschedule an alarm if necessary. */
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if (next_time > 0) {
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if (sys_setalarm(next_time, 1) != OK)
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panic("expire_timers: couldn't set alarm");
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}
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}
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