terom@1: #include <avr/interrupt.h>
terom@1: 
terom@1: #include "stdlib.h"
terom@1: #include "timer.h"
terom@1: 
terom@1: void timer_init (void)
terom@1: {
terom@1:     TCCR1A = (
terom@1:             // OC1A output pin disconnected
terom@1:             0b00 << COM1A0
terom@1:             // OC1B output pin disconnected
terom@1:         |   0b00 << COM1B0
terom@1:             // no PWM
terom@1:         |   0b00 << WGM10
terom@1:     );
terom@1:     TCCR1B = (
terom@1:             // CTC mode
terom@1:             0b01 << WGM12
terom@1:     );
terom@1:     TCCR1C = 0;
terom@1: }
terom@1: 
terom@1: static void timer1_set ()
terom@1: {
terom@1:     sbi(&TIMER_FLAGS, TIMER1_BUSY);
terom@1: }
terom@1: 
terom@1: static void timer1_start (short cycles)
terom@1: {
terom@1:     // count up from zero...
terom@1:     TCNT1 = 0;
terom@1: 
terom@1:     // ...to the given number of timer cycles
terom@1:     OCR1A = cycles;
terom@1: 
terom@1:     // start!
terom@1:     timer1_set();
terom@1:     TIMSK1 = (
terom@1:             // OCA interrupt
terom@1:             0b1 << OCIE1A       // enable
terom@1:     );
terom@1:     TCCR1B = (
terom@1:             // WGM
terom@1:             0b01  << WGM12      // CTC
terom@1: 
terom@1:             // clocksource
terom@1:         |   0b101 << CS10       // 1024'th
terom@1:     );
terom@1: }
terom@1: 
terom@1: /*
terom@1:  * Keep the timer running, but clear the flag..
terom@1:  */
terom@1: static void timer1_clear ()
terom@1: {
terom@1:     cbi(&TIMER_FLAGS, TIMER1_BUSY);
terom@1: }
terom@1: 
terom@1: /*
terom@1:  * Stop the timer at its current value.
terom@1:  */
terom@1: static void timer1_stop ()
terom@1: {
terom@1:     // WGM: normal
terom@1:     // clocksource: stop
terom@1:     TCCR1B = 0;
terom@1: 
terom@1:     timer1_clear();
terom@1: }
terom@1: 
terom@1: ISR(TIMER1_COMPA_vect)
terom@1: {
terom@1:     timer1_clear();
terom@1: 
terom@1:     // cpu will wake up from sleep()
terom@1: }
terom@1: 
terom@1: /*
terom@1:  * Sleep on timer1 interrupt.
terom@1:  *
terom@1:  * Starts fresh timer that sleeps given cycles if given, or continues on the running timer.
terom@1:  *
terom@1:  * Returns 1 on timeout, 0 on other interrupt.
terom@1:  */
terom@1: byte timer_sleep (unsigned cycles)
terom@1: {
terom@1:     if (cycles) {
terom@1:         // set fresh timer
terom@1:         timer1_start(cycles);
terom@1:     } else {
terom@1:         // wait for next cycle...
terom@1:         timer1_set();
terom@1:     }
terom@1: 
terom@1:     // sleep while timer is running
terom@1:     // XXX: atomic?
terom@1:     if (tbi(&TIMER_FLAGS, TIMER1_BUSY)) {
terom@1:         // TODO: PRR
terom@1:         SMCR = (
terom@1:                 // idle sleep
terom@1:                 (0b00 << SM0)
terom@1: 
terom@1:                 // enable sleep
terom@1:             |   (0b1 << SE)
terom@1:         );
terom@1: 
terom@1:         // sleep
terom@1:         __asm__ ( "sleep" :: );
terom@1: 
terom@1:         // cleanup
terom@1:         SMCR = 0;
terom@1:     }
terom@1: 
terom@1:     if (tbi(&TIMER_FLAGS, TIMER1_BUSY)) {
terom@1:         // interrupt
terom@1:         return 0;
terom@1: 
terom@1:     } else {
terom@1:         // timeout
terom@1:         return 1;
terom@1:     }
terom@1: }