void
do_vop(optype,TARG,left,right)
STR *TARG;
STR *left;
STR *right;
{
    register char *s;
    register char *l = str_get(left);
    register char *r = str_get(right);
    register int len;

    len = left->str_cur;
    if (len > right->str_cur)
	len = right->str_cur;
    if (TARG->str_cur > len)
	TARG->str_cur = len;
    else if (TARG->str_cur < len) {
	STR_GROW(TARG,len);
	(void)memzero(TARG->str_ptr + TARG->str_cur, len - TARG->str_cur);
	TARG->str_cur = len;
    }
    TARG->str_pok = 1;
    TARG->str_nok = 0;
    s = TARG->str_ptr;
    if (!s) {
	str_nset(TARG,"",0);
	s = TARG->str_ptr;
    }
    switch (optype) {
    case O_BIT_AND:
	while (len--)
	    *s++ = *l++ & *r++;
	break;
    case O_XOR:
	while (len--)
	    *s++ = *l++ ^ *r++;
	goto mop_up;
    case O_BIT_OR:
	while (len--)
	    *s++ = *l++ | *r++;
      mop_up:
	len = TARG->str_cur;
	if (right->str_cur > len)
	    str_ncat(TARG,right->str_ptr+len,right->str_cur - len);
	else if (left->str_cur > len)
	    str_ncat(TARG,left->str_ptr+len,left->str_cur - len);
	break;
    }
}