/*
 * =====================================================================================
 *
 * ________        .__        __    ________               ____  ________
 * \_____  \  __ __|__| ____ |  | __\______ \   _______  _/_   |/  _____/
 *  /  / \  \|  |  \  |/ ___\|  |/ / |    |  \_/ __ \  \/ /|   /   __  \
 * /   \_/.  \  |  /  \  \___|    <  |    `   \  ___/\   / |   \  |__\  \
 * \_____\ \_/____/|__|\___  >__|_ \/_______  /\___  >\_/  |___|\_____  /
 *        \__>             \/     \/        \/     \/                 \/
 *
 *                                  www.optixx.org
 *
 *
 *        Version:  1.0
 *        Created:  07/21/2009 03:32:16 PM
 *         Author:  david@optixx.org
 *
 * =====================================================================================
 */




#include <stdint.h>
#include <stdio.h>
#include <avr/io.h>
#include <avr/io.h>
#include <avr/interrupt.h>      /* for sei() */

#include "debug.h"
#include "info.h"
#include "sram.h"


extern uint8_t snes_reset_line;

#ifndef OCR1A
#define OCR1A OCR1              // 2313 support
#endif

#ifndef WGM12
#define WGM12 CTC1              // 2313 support
#endif

// #define XTAL 11059201L // nominal value
#define XTAL        20000000UL

#define DEBOUNCE    500L        // debounce clock (256Hz = 4msec)

#define uint8_t unsigned char
#define uint unsigned int

uint16_t prescaler;
uint16_t volatile second;       // count seconds


ISR(SIG_OUTPUT_COMPARE1A)
{


#if XTAL % DEBOUNCE             // bei rest
    OCR1A = 20000000UL / DEBOUNCE - 1;  // compare DEBOUNCE - 1 times
#endif
    if (--prescaler == 0) {
        prescaler = (uint16_t) DEBOUNCE;
        second++;               // exact one second over
#if XTAL % DEBOUNCE             // handle remainder
        OCR1A = XTAL / DEBOUNCE + XTAL % DEBOUNCE - 1;  // compare once per second
#endif
    }
}

void timer_start(void)
{
    TCCR1B = (1 << WGM12) | (1 << CS10);        // divide by 1
    // clear on compare
    OCR1A = XTAL / DEBOUNCE - 1UL;      // Output Compare Register
    TCNT1 = 0;                  // Timmer startet mit 0
    second = 0;
    prescaler = (uint16_t) DEBOUNCE;    // software teiler
    TIMSK1 = 1 << OCIE1A;       // beim Vergleichswertes Compare Match 
    // Interrupt (SIG_OUTPUT_COMPARE1A)
    sei();

}

uint16_t timer_stop_int(void)
{
    uint16_t t = ((DEBOUNCE - prescaler) / DEBOUNCE) + second;
    return t;
}