/****************************************************************/
/* Paulo Pedreiras, Set/2003                                    */
/* UA, Sistemas de Tempo Real, Lab                              */
/*                                                              */
/* Calcula e mostra a diferenca entre os tempos de              */
/* activacao de instancias consecutiva de um "loop de controlo" */
/****************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <ctype.h>
#include <math.h>

int main(int argc, char **argv)
{
  struct timeval tact,tant; 
  long d_s,d_ms,d_us,tsleep;

  long i;
  float lixo;

  char toutp;
  int first_flag=0;

      
  /* Check input args */
  if(argc != 3 || (tolower(argv[2][0]) != 'y' && tolower(argv[2][0]) != 'n') ){
    printf("\n Usage: tick msecs output({y,n})\n");
    return 1;
  }
  tsleep=atol(argv[1])*1000;
  toutp=tolower(argv[2][0]);

  /* Welcome message */
  printf("\n tick: Sleeping by %ld miliseconds\n", atol(argv[1]));
  
  /* Main loop */
  while(1){
    /* Get current system time */
    gettimeofday(&tact,NULL);
    //printf("\n sec:%ld usec:%ld",tact.tv_sec, tact.tv_usec);
    if(first_flag){ /* If not first instance */
      
      /* Compute delay between activations */
      d_s=tact.tv_sec-tant.tv_sec;
      if(d_s==0)
	d_us=tact.tv_usec-tant.tv_usec;
      else
	{
	  d_us=tact.tv_usec + (1000000-tant.tv_usec);
	  if(d_us < 1000000)
	    d_s--;
	  else
	    d_us-=1000000;
	  
	}
      
      d_ms=d_us/1000;

      if(toutp == 'y'){ 
	if(d_s>0)
	  printf("\n Slep %lds:%ldms",d_s,d_ms);
	else
	  printf("\n Slep %ldms",d_ms);
      }
    }
    else
      first_flag=1;

    tant=tact;  

    for(i=0;i<100000L;i++)
      lixo=sqrt(125);
    
    if(argv[1]!=0)
      usleep(atol(argv[1])*1000);
  }

  return 0;

}