#include <mega8.h>

static float Fx;
unsigned long int N1, N;
unsigned int M1, M;
unsigned int Perepol_Timer0=0, Perepol_Timer1=0;
unsigned int count_T1, count_T0;

// Timer 0 overflow interrupt service routine
interrupt [TIM0_OVF] void timer0_ovf_isr(void){
Perepol_Timer0++;
}

// Timer 1 overflow interrupt service routine
interrupt [TIM1_OVF] void timer1_ovf_isr(void){
Perepol_Timer1++;
}

// Timer 1 input capture interrupt service routine
interrupt [TIM1_CAPT] void timer1_capt_isr(void){
TIMSK&=0xDF;
count_T0=TCNT0;
count_T1=ICR1;
}


void main(void)
{
// Input/Output Ports initialization

PORTB=0x00;
DDRB=0x00;

PORTC=0x00;
DDRC=0x00;

PORTD=0x00;
DDRD=0x00;

// Timer/Counter 0 initialization
// Clock source: T0 pin Rising Edge
TCCR0=0x07;
TCNT0=0x00;

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 8000,000 kHz
// Mode: Normal top=FFFFh
// OC1A output: Discon.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Rising Edge
// Timer 1 Overflow Interrupt: On
// Input Capture Interrupt: On
// Compare A Match Interrupt: Off
// Compare B Match Interrupt: Off
TCCR1A=0x00;
TCCR1B=0x41;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0x00;
OCR1BH=0x00;
OCR1BL=0x00;

// Timer/Counter 2 initialization
// Clock source: System Clock
// Clock value: Timer 2 Stopped
// Mode: Normal top=FFh
// OC2 output: Disconnected
ASSR=0x00;
TCCR2=0x00;
TCNT2=0x00;
OCR2=0x00;

// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
MCUCR=0x00;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x05;

// Analog Comparator initialization
// Analog Comparator: Off
// Analog Comparator Input Capture by Timer/Counter 1: Off
ACSR=0x80;
SFIOR=0x00;

// Global enable interrupts
#asm("sei")
while (1) {
Perepol_Timer1=0;
N1=Perepol_Timer1*65535+count_T1;
M1=Perepol_Timer0*255+count_T0;
while (Perepol_Timer1<12){
};
TIMSK|=0x20;
N=((unsigned long int)(Perepol_Timer1)*65535+(unsigned int)(count_T1))-N1;
M=(Perepol_Timer0*255+count_T0)-M1;
Fx=(float)8000000.0*(float)M/(float)N;
};
TIMSK|=0x20;
}