#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/sleep.h>
#include <avr/eeprom.h>
#include "I2C.h"

void tea5767SetFreq(unsigned int);

#define MAX_STATIONS 32
#define FM_FREQ_MIN  870
#define FM_FREQ_MAX 1075

unsigned char vars = 0b0000;//save, next, -, +
EEMEM unsigned int stations[MAX_STATIONS] = { 1007, 1045, 1016, 924, 979, 1000, 1037, 877, 1064, 952, 1068, 997, 976, 894, 1025, 964, 945, 995, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN, FM_FREQ_MIN };
unsigned char divider = 0;
unsigned char currentStation = 0;
unsigned int freq = 0;

ISR (TIM0_COMPA_vect) //~20Hz
{
   if (++divider >= 5) //~4Hz
   {
      if (!(PINB & (1 << 5))) vars |= 1; //+
      if (!(PINB & (1 << 3))) vars |= 1 << 1; //-
      if (!(PINB & (1 << 4))) vars |= 1 << 2; else vars &= ~(1 << 2); //next
      if (!(PINB & (1 << 1))) vars |= 1 << 3; else vars &= ~(1 << 3); //save
      divider = 0;
   }
}

int main(void)
{
   if (freq == 0)
   freq = eeprom_read_word(&stations[currentStation]);

   CLKPR = 0x00;

   // Input/Output Ports initialization
   // Port B initialization
   // Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
   // State5=P State4=P State3=P State2=T State1=P State0=T
   DDRB = 0b000000;
   PORTB = 0b111010;

   // Timer/Counter 0 initialization
   // Clock source: System Clock
   // Clock value: 4,688 kHz
   // Mode: CTC top=OCR0A
   // OC0A output: Disconnected
   // OC0B output: Disconnected
   TCCR0A = 0x02;
   TCCR0B = 0x05;
   TCNT0 = 0x00;
   OCR0A = 0xea;
   OCR0B = 0x00;

   // Timer/Counter 0 Interrupt(s) initialization
   TIMSK0 = 0x04;

   set_sleep_mode(SLEEP_MODE_IDLE);
   
   asm volatile("sei");
   
   /* Replace with your application code */
   while (1)
   {
      if (vars & 1) //+
      {
         if (++freq >= FM_FREQ_MAX) freq = FM_FREQ_MIN;
         tea5767SetFreq(freq);
         vars &= ~1;
      }
      if (vars & (1 << 1)) //-
      {
         if (--freq <= FM_FREQ_MIN) freq = FM_FREQ_MAX;
         tea5767SetFreq(freq);
         vars &= ~(1 << 1);
      }
      if (vars & (1 << 2)) //next
      {
         currentStation = (currentStation < MAX_STATIONS) ? (currentStation - 1 > 0 && eeprom_read_word(&stations[currentStation]) == eeprom_read_word(&stations[currentStation - 1])) ? 0 : currentStation + 1 : 0;
         freq = eeprom_read_word(&stations[currentStation]);
         tea5767SetFreq(freq);
         while (vars & (1 << 2)) _delay_us(30);
      }
      if (vars & (1 << 3)) //save
      {
         eeprom_update_word(&stations[currentStation], freq);
         while (vars & (1 << 3)) _delay_us(30);
      }
      sleep_enable();
      sleep_cpu();
   }
}

void tea5767SetFreq(unsigned int freq)
{
   unsigned int div = ((unsigned long)freq * 12500 + 28125) >> 10; // /1024
   unsigned char var1 = (div >> 8) & 0x3F;
   asm volatile ("cli");
   i2c_start(0xC0);
   i2c_write(var1);
   i2c_write(div & 0xff);
   i2c_write(0b00001010);
   i2c_write(0b00011110);
   i2c_write(0);
   i2c_stop();
   asm volatile ("sei");
}