terom@52: #include <avr/interrupt.h>
terom@52: 
terom@52: #define TIMER_FLAGS     GPIOR0
terom@52: #define TIMER1_BUSY     1
terom@52: 
terom@52: /*
terom@52:  * Setup timers.
terom@52:  */
terom@52: void timer_init (void)
terom@52: {
terom@52:     TCCR1A = (
terom@52:             // OC1A output pin disconnected
terom@52:             0b00 << COM1A0
terom@52:             // OC1B output pin disconnected
terom@52:         |   0b00 << COM1B0
terom@52:             // no PWM
terom@52:         |   0b00 << WGM10
terom@52:     );
terom@52:     TCCR1B = (
terom@52:             // CTC mode
terom@78:             0b01 << WGM12
terom@52:     );
terom@52:     TCCR1C = 0;
terom@52: }
terom@52: 
terom@78: static void timer1_set ()
terom@78: {
terom@78:     sbi(&TIMER_FLAGS, TIMER1_BUSY);
terom@78: }
terom@78: 
terom@52: void timer1_start (short cycles)
terom@52: {
terom@52:     // count up from zero...
terom@52:     TCNT1 = 0;
terom@52: 
terom@52:     // ...to the given number of timer cycles
terom@52:     OCR1A = cycles;
terom@52: 
terom@52:     // start!
terom@78:     timer1_set();
terom@52:     TIMSK1 = (
terom@52:             // OCA interrupt
terom@52:             0b1 << OCIE1A       // enable
terom@52:     );
terom@52:     TCCR1B = (
terom@52:             // WGM
terom@52:             0b01  << WGM12      // CTC
terom@52: 
terom@52:             // clocksource
terom@52:         |   0b101 << CS10       // 1024'th
terom@52:     );
terom@52: }
terom@52: 
terom@78: /*
terom@78:  * Keep the timer running, but clear the flag..
terom@78:  */
terom@78: static void timer1_clear ()
terom@78: {
terom@78:     cbi(&TIMER_FLAGS, TIMER1_BUSY);
terom@78: }
terom@78: 
terom@78: /*
terom@78:  * Stop the timer at its current value.
terom@78:  */
terom@52: static void timer1_stop ()
terom@52: {
terom@52:     // WGM: normal
terom@52:     // clocksource: stop
terom@52:     TCCR1B = 0;
terom@52: 
terom@78:     timer1_clear();
terom@52: }
terom@52: 
terom@52: ISR(TIMER1_COMPA_vect)
terom@52: {
terom@78:     timer1_clear();
terom@52: 
terom@78:     // cpu will wake up from sleep()
terom@52: }
terom@52: 
terom@52: /*
terom@52:  * Sleep on timer1 interrupt.
terom@53:  *
terom@78:  * Starts fresh timer that sleeps given cycles if given, or continues on the running timer.
terom@78:  *
terom@78:  * Returns 1 on timeout, 0 on other interrupt.
terom@52:  */
terom@63: char timer_sleep (unsigned cycles)
terom@52: {
terom@54:     if (cycles) {
terom@78:         // set fresh timer
terom@54:         timer1_start(cycles);
terom@78:     } else {
terom@78:         // wait for next cycle...
terom@78:         timer1_set();
terom@54:     }
terom@52: 
terom@78:     // sleep while timer is running
terom@78:     // XXX: atomic?
terom@78:     if (tbi(&TIMER_FLAGS, TIMER1_BUSY)) {
terom@78:         // TODO: PRR
terom@78:         SMCR = (
terom@78:                 // idle sleep
terom@78:                 (0b00 << SM0)
terom@52: 
terom@78:                 // enable sleep
terom@78:             |   (0b1 << SE)
terom@78:         );
terom@52: 
terom@78:         // sleep
terom@78:         __asm__ ( "sleep" :: );
terom@78: 
terom@78:         // cleanup
terom@78:         SMCR = 0;
terom@78:     }
terom@78: 
terom@78:     if (tbi(&TIMER_FLAGS, TIMER1_BUSY)) {
terom@78:         // interrupt
terom@78:         return 0;
terom@78: 
terom@78:     } else {
terom@54:         // timeout
terom@54:         return 1;
terom@53:     }
terom@52: }
terom@52: 
terom@52: