65 lines
1.8 KiB
C
65 lines
1.8 KiB
C
/**
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* \file
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* \brief Support of one-shot timers
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*
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* To simplify things we maintain one timer for the scheduler, and one for the
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* wakeup infrastructure. Each of these subsystems is responsible for updating
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* their timer value. When an update happens, we update the hardware timer if
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* the previous (global) timer has changed.
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*/
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/*
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* Copyright (c) 2011, ETH Zurich.
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* All rights reserved.
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*
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* This file is distributed under the terms in the attached LICENSE file.
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* If you do not find this file, copies can be found by writing to:
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* ETH Zurich D-INFK, Universitaetstrasse 6, CH-8092 Zurich. Attn: Systems Group.
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*/
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#include <timer.h>
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#include <kernel.h>
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/* these are systime_t i.e., absolute time values in ms */
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static systime_t next_sched_timer = TIMER_INF; //< timer for scheduler
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static systime_t next_wakeup_timer = TIMER_INF; //< timer for wakeups
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static systime_t last_timer; //< last set timer
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#define MIN(x,y) ((x<y) ? (x) : (y))
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static void update_timer(void)
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{
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systime_t timer = MIN(next_sched_timer, next_wakeup_timer);
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assert(timer != 0);
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if (last_timer != timer) {
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#if 0 /* does not seem to create a problem */
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if (timer == TIMER_INF) {
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printk(LOG_WARN, "********* %s:%s() timer == TIMER_INF\n", __FILE__, __FUNCTION__);
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//timer = kernel_now + kernel_timeslice;
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}
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#endif
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arch_set_timer(last_timer = timer);
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}
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}
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/**
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* \brief update the wakeup timer
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* \param t absolute time in ms for the next interrupt
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*/
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void update_wakeup_timer(systime_t t)
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{
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next_wakeup_timer = t;
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update_timer();
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}
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/**
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* \brief update the sched timer
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* \param t absolute time in ms for the next interrupt
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*/
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void update_sched_timer(systime_t t)
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{
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next_sched_timer = t;
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update_timer();
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}
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