#include<stdio.h>
#include<fcntl.h>
#include<sys/stat.h>
#include<sys/types.h>
#include<sys/time.h>
#include <termios.h>
#include <unistd.h>

void fd_setup(int , int , int );

int main()
{
				int fd,pid;
				struct timeval sndtime, recvtime;

				fd = open("/dev/ttyS0" , O_RDWR );

				if (fd == -1)
								perror("OPEN");

				fd_setup(fd, 9600, 0);

				if( ( pid = vfork() ) == 0 ) {
								/* child waiting : to recv data from serial
								 * port
								 */
								char buffer[ 100 + 1 ] = "\0";
								int count = read( fd, buffer, sizeof( buffer ) );

								printf("child created \n");	
								gettimeofday( &recvtime, NULL );
								printf( "after read : secs\t: %u\tusecs\t: %u\n",
																recvtime.tv_sec, recvtime.tv_usec );
								buffer[ count ] = '\0';
								printf( "count = %d buffer %s ",count, buffer );
								printf( "diff sec\t: %u\tusec\t: %u\n",
																recvtime.tv_sec - sndtime.tv_sec,
																recvtime.tv_usec - sndtime.tv_usec );
								exit(0);

				} else {
								puts( "enter to start" );
								getchar();
								gettimeofday( &sndtime, NULL );
								printf( "before write : secs\t: %u\tusecs\t: %u\n",
																sndtime.tv_sec, sndtime.tv_usec );
								write( fd , "Ballu" , 5);

								gettimeofday( &sndtime, NULL );

								printf( "after write : secs\t: %u\tusecs\t: %u\n",
																sndtime.tv_sec, sndtime.tv_usec );

				}

}
void fd_setup(int fd, int speed, int flow)
{
  struct termios t;

  if (fd < 0)
  {
    perror("fd_setup");
    exit(1);
  }
        
  if (tcgetattr(fd, &t) < 0)
  {  
    perror("tcgetattr");
    exit(1);
  }

  cfmakeraw(&t);
        
  t.c_cflag &= ~CBAUD;
  t.c_cflag |= translate_speed(speed) | CS8 | CLOCAL;
  t.c_oflag = 0; /* turn off output processing */
  t.c_lflag = 0; /* no local modes */
  
  if (flow)
    t.c_cflag |= CRTSCTS;
  else
    t.c_cflag &= ~CRTSCTS;
  
  if (tcsetattr(fd, TCSANOW, &t) < 0)
  {
    perror("fd_setup : tcsetattr");
    exit(1);
  }
  return;
}
int translate_speed(int spd)
{
  int speed_c = 0;

  switch(spd)
  {
   case 9600:
    speed_c = B9600;
    break;
   case 19200:
    speed_c = B19200;
    break;
   case 38400:
    speed_c = B38400;
    break;
   case 57600:
    speed_c = B57600;
    break;
   case 115200:
    speed_c = B115200;
    break;
   case 230400:
    speed_c = B230400;
    break;
   case 460800:
    speed_c = B460800;
    break;
   default:
    printf("Bad baudrate %d.\n", spd);
    break;
  }
  return speed_c;
}