/*
 * $Revision: 1.10 $
 * $Date: 2011-02-07 21:39:21 $
 * $Author: higgins $
 * $State: Exp $
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include "pine_car.h"

// there are two main things going on here:
// (1) the leds are being pulsed to power consumption, and the
//     pulsing is being staggered to reduce switching spikes.
// (2) on a much slower scale, two leds are flashing.
//
// (1) should not be perceptable, (2) should.
// the timer is set up to create an interrupt every 1mS

Led data[N_LEDS] = {
//      {<delay>, <mask>, <pulse_on_count>, <pulse_count_togo>},
        {0, _BV(0), 1, 0},
        {2, _BV(1), 1, 0},
        {4, _BV(2), 4, 0},
        {6, _BV(3), 4, 0},
        {8, _BV(4), 10, 0},
        {10, _BV(5), 10, 0},
    };

// incremented by isr...
uint16_t count_ms = 0;

ISR(TIMER1_COMPA_vect) {
    uint8_t phase = count_ms & 0x0f;    // use lower 4 bits for delay...
    uint8_t bits = LED_PORT;            // assign to LED_PORT at end...

    // turn off any leds that have 'expired'...
    for(uint8_t i = 0; i<N_LEDS; i++) {
        data[i].pulse_count_togo--;
        if (data[i].pulse_count_togo == 0) {
            bits &= ~data[i].mask;
        }
        // turn on current led...
        if (data[i].delay == phase) {
            data[i].pulse_count_togo = data[i].pulse_on_count;
            bits |= data[i].mask;
        }
    }

    // handle slow flashing leds...
    uint8_t slow_count = (count_ms>>8) & 0x1;
    if (slow_count) {
        bits &= ~_BV(2);
    } else {
        bits &= ~_BV(3);
    }

    LED_PORT = bits;
    count_ms++;
}

int main(void) {

    // just for readability...
    const static int NO_PRESCALING = _BV(CS10);
    const static int MODE_4_CTC = _BV(WGM12);
    const static int TIMER1_OUT_COMP_A_INT_ENABLE = _BV(OCIE1A);
    const static int DELAY = 999;       // 1mS @ 1 Mhz

    TCCR1B = MODE_4_CTC|NO_PRESCALING;
    TIMSK = TIMER1_OUT_COMP_A_INT_ENABLE;
    OCR1A = DELAY;
    LED_PORT = 0;       // all off...
    sei();

    DDRB = 0xFF;        // set port B to output only

    while (1) {
    }
}