fix_input_buffer(char_u *buf, int len)
{
    int		i;
    char_u	*p = buf;

    /*
     * Two characters are special: NUL and K_SPECIAL.
     * When compiled With the GUI CSI is also special.
     * Replace	     NUL by K_SPECIAL KS_ZERO	 KE_FILLER
     * Replace K_SPECIAL by K_SPECIAL KS_SPECIAL KE_FILLER
     * Replace       CSI by K_SPECIAL KS_EXTRA   KE_CSI
     */
    for (i = len; --i >= 0; ++p)
    {
#ifdef FEAT_GUI
	/* When the GUI is used any character can come after a CSI, don't
	 * escape it. */
	if (gui.in_use && p[0] == CSI && i >= 2)
	{
	    p += 2;
	    i -= 2;
	}
# ifndef MSWIN
	/* When the GUI is not used CSI needs to be escaped. */
	else if (!gui.in_use && p[0] == CSI)
	{
	    mch_memmove(p + 3, p + 1, (size_t)i);
	    *p++ = K_SPECIAL;
	    *p++ = KS_EXTRA;
	    *p = (int)KE_CSI;
	    len += 2;
	}
# endif
	else
#endif
	if (p[0] == NUL || (p[0] == K_SPECIAL
		    // timeout may generate K_CURSORHOLD
		    && (i < 2 || p[1] != KS_EXTRA || p[2] != (int)KE_CURSORHOLD)
#if defined(MSWIN) && (!defined(FEAT_GUI) || defined(VIMDLL))
		    // Win32 console passes modifiers
		    && (
# ifdef VIMDLL
			gui.in_use ||
# endif
			(i < 2 || p[1] != KS_MODIFIER))
#endif
		    ))
	{
	    mch_memmove(p + 3, p + 1, (size_t)i);
	    p[2] = K_THIRD(p[0]);
	    p[1] = K_SECOND(p[0]);
	    p[0] = K_SPECIAL;
	    p += 2;
	    len += 2;
	}
    }
    *p = NUL;		// add trailing NUL
    return len;
}
Unknown