/* demonstrate the use of terminal setting */
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <termio.h>

/* global variable */
struct termio savetty;

/* function prototypes */
void sigcatch();
void change_tty(struct termio *);
struct termio * settty_param(struct termio);

int main(int argc, char* argv[])   {

  struct termio * newtty;
  int nrd;
  int i;
  char buf[32];

  signal(SIGINT,sigcatch);  /* catch the 'interrupt' signal, i.e., Ctrl-C*/

  /* retrieve and save the current terminal setting into 'savetty' */
  if (ioctl(0,TCGETA,&savetty) == -1)     {
    fprintf(stderr, "ioctl failed: not a tty\n");
    exit(1);
  }

  /* the newtty sets a new collection of tty values */
  newtty = settty_param(savetty);
  change_tty(newtty);

    for (;;)  {
      nrd = read(0,buf,sizeof(buf));
      buf[nrd] = 0;
      printf("read %d ascii %d chars '%s'\n",nrd,buf[0],buf);
      for (i = 0; i < nrd; i ++)
	printf("read '%c' print '%c'\n",buf[i],buf[i]+1);
      if (buf[0] == 'c') { /* we use char 'c' to signal change terminal */
	printf("change tty\n");
	change_tty(newtty);
      }
    }
}

/* signal handling */
void sigcatch()  {

  ioctl(0,TCSETAF,&savetty);
  /*   exit(); */
  printf(" you typed control - C\n");
}

/* set new tty parameters */
struct termio * settty_param(struct termio orig_tty) {

  struct termio * newtty;
  newtty = (struct termio *)malloc(sizeof(struct termio));

  (*newtty) = orig_tty;

  newtty->c_lflag &= ~ICANON;   /* turn off canonical mode */
  newtty->c_lflag &= ~ECHO;     /* turn off echoing */
  newtty->c_cc[VMIN] = 1;       /* minimum 1 chars */
  newtty->c_cc[VTIME] = 100;    /* 10 sec interval */

  return newtty;
}

/* acutally change tty setting with the given pamaraters */
void change_tty(struct termio * tty_param) {

  /* actually setting the terminal config with the newtty */
  if (ioctl(0,TCSETAF,tty_param) == -1)     {
    printf("cannot put tty into raw mode \n");
    exit(1);
  }
}