#include <stdio.h>
#include <sys/time.h>

#define MAXAV 10

void main(void)
{
FILE *fp;
int ret;
int frequency, periodes,rpm,i;
double dperiode;
int parameter;
unsigned char timespan = 1;
int samples=0;
struct timeval tv,tv_start;
int avval[MAXAV];

	gettimeofday(&tv_start,NULL);

	// configure frequency counter parameters
	fp = fopen("/dev/fcounter","wb");
	if(fp)
	{
		parameter = 0xaa370000;
		parameter += timespan;
		
		fwrite(&parameter,4,1,fp);
		
		fclose(fp);
	}
	else
		printf("Cannot open device \n");
 
  
  
	// Read the counter result (exit with Ctrl-C)
	fp = fopen("/dev/fcounter","rb");
    if(fp)
    {
		while(1)
		{
			ret = fread(&frequency,4,1,fp);
			if(ret<=0) break;
			ret = fread(&periodes,4,1,fp);
			if(ret<=0) break;
			frequency /= timespan;
			dperiode = 512.0/(double)periodes;	// 1 jiffies entspricht 512 Hz
			
			// bei Torzeit 1s und Priodenzaehler 512 Hz, ist die Periodenmessung bei 22 Hz genauer, dar?ber die Frequenzmessung
			if(frequency < 22)
			{
				rpm = (int)(dperiode*60.0);
				printf("Periodic measurement: ");
			}
			else
			{
				rpm = frequency*60;
				printf("Frquency measurement: ");
			}
			
			for(i=(MAXAV-1); i>0; i--) avval[i] = avval[i-1];
			avval[0] = rpm;
			
			rpm = 0;
			for(i=0; i<MAXAV; i++) rpm+=avval[i];
			rpm/=MAXAV;
			
			gettimeofday(&tv,NULL);
			printf("[%d] Frequency: %d Hz. Periodes: %.1f. rpm=%d\n",tv.tv_sec - tv_start.tv_sec,frequency,dperiode,rpm);
			usleep(250000);
		}
	}
	else
	  printf("Cannot open device \n");
}