/*
  so.c - A simple shift-in/shift-out filter.

  Reads from standard input, writes to standard output.
  Input is text encoded in an 8-bit character set.
  Output is 7-bit text with imbedded <SO> and <SI> sequences.

  F. da Cruz, Columbia University, 1991.
*/
#include <stdio.h>

main() {
    int i = 0;				/* Int version of current character */
    unsigned char c;			/* Char version of current char */
    int state = 0;			/* Shift In/Out state */

    char *latin1 = "\033-A";		/* ISO 2022: designate Latin1 to G1 */
/*  printf("%s", latin1); */        	/* Uncomment if necessary */

    while ((i = getchar()) != EOF) {	/* Get a character, test for end. */
	c = i;				/* Convert to character. */
	if (c > 127) {			/* If an 8-bit character */
	    if (state == 0) {		/* and we're not shifted */
		putchar('\16');		/* Output SO = Ctrl-N */
		state = 1;		/* Change state to shifted */
	    }
	} else if (state == 1) {	/* 7-bit character and shifted */
	    putchar('\17');		/* Output SI = Ctrl-O */
	    state = 0;			/* Change state to unshifted */
	}
	putchar(c & 127);		/* Now output the character itself */
    }					/* (low-order 7 bits only) */
}