50 lines
883 B
C
50 lines
883 B
C
#include "time.h"
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#include "conf.h"
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#include <avr/interrupt.h>
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#include <avr/io.h>
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volatile struct eigentime_s _eigentime_ms;
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void
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time_init(void)
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{
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_eigentime_ms.low = 0;
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_eigentime_ms.high = 0;
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_eigentime_ms.tenth = 0;
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// prescaler is 64.
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TCCR0B = _BV(CS00) | _BV(CS01);
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TIMSK0 |= _BV(TOIE0);
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sei();
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}
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void
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get_eigentime(struct eigentime_s * time)
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{
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time->low = _eigentime_ms.low;
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time->high = _eigentime_ms.high;
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}
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ISR(TIMER0_OVF_vect)
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{
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unsigned int last_eigentime_low = _eigentime_ms.low;
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unsigned int ms;
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// well basically at 20Mhz milliseconds are not precise enough.
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_eigentime_ms.tenth += TIME_TENTH_MILLIS_PER_OVERFLOW;
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if(_eigentime_ms.tenth > 10)
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{
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ms = _eigentime_ms.tenth / 10;
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_eigentime_ms.low += ms;
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_eigentime_ms.tenth -= 10 * ms;
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}
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// Handle the overflow.
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if(_eigentime_ms.low < last_eigentime_low)
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{
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_eigentime_ms.high++;
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}
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}
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