#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <wiringPi.h>

#define IN_PIN    6

static volatile int globalCounter = 0 ;

void myInterrupt (void) {
  ++globalCounter ;
}

int main (void) {
  int myCounter   = 0 ;
  int lastCounter = 0 ;

  if (wiringPiSetup () < 0) {
    fprintf (stderr, "Unable to setup wiringPi: %s\n", strerror (errno)) ;
    return 1 ;
  }

  pinMode (IN_PIN,  INPUT) ;

  if (wiringPiISR (IN_PIN, INT_EDGE_FALLING, &myInterrupt) < 0) {
    fprintf (stderr, "Unable to setup ISR: %s\n", strerror (errno)) ;
    return 1 ;
  }

  for (;;)   {
    printf ("Waiting ... ") ; fflush (stdout) ;

    while (myCounter == globalCounter)
      delay (1000) ;
    printf (" Done. counter: %6d: %6d\n",
    globalCounter, myCounter - lastCounter) ;
    lastCounter = myCounter ;
    myCounter   = globalCounter ;
  }

  return 0 ;
}