mb_init(void)
{
    int		i;
    int		idx;
    int		n;
    int		enc_dbcs_new = 0;
#if defined(USE_ICONV) && !defined(MSWIN) && !defined(WIN32UNIX) \
	&& !defined(MACOS_CONVERT)
# define LEN_FROM_CONV
    vimconv_T	vimconv;
    char_u	*p;
#endif

    if (p_enc == NULL)
    {
	// Just starting up: set the whole table to one's.
	for (i = 0; i < 256; ++i)
	    mb_bytelen_tab[i] = 1;
	input_conv.vc_type = CONV_NONE;
	input_conv.vc_factor = 1;
	output_conv.vc_type = CONV_NONE;
	return NULL;
    }

#ifdef MSWIN
    if (p_enc[0] == 'c' && p_enc[1] == 'p' && VIM_ISDIGIT(p_enc[2]))
    {
	CPINFO	cpinfo;

	// Get info on this codepage to find out what it is.
	if (GetCPInfo(atoi((char *)p_enc + 2), &cpinfo) != 0)
	{
	    if (cpinfo.MaxCharSize == 1)
	    {
		// some single-byte encoding
		enc_unicode = 0;
		enc_utf8 = FALSE;
	    }
	    else if (cpinfo.MaxCharSize == 2
		    && (cpinfo.LeadByte[0] != 0 || cpinfo.LeadByte[1] != 0))
	    {
		// must be a DBCS encoding, check below
		enc_dbcs_new = atoi((char *)p_enc + 2);
	    }
	    else
		goto codepage_invalid;
	}
	else if (GetLastError() == ERROR_INVALID_PARAMETER)
	{
codepage_invalid:
	    return N_(e_not_valid_codepage);
	}
    }
#endif
    else if (STRNCMP(p_enc, "8bit-", 5) == 0
	    || STRNCMP(p_enc, "iso-8859-", 9) == 0)
    {
	// Accept any "8bit-" or "iso-8859-" name.
	enc_unicode = 0;
	enc_utf8 = FALSE;
    }
    else if (STRNCMP(p_enc, "2byte-", 6) == 0)
    {
#ifdef MSWIN
	// Windows: accept only valid codepage numbers, check below.
	if (p_enc[6] != 'c' || p_enc[7] != 'p'
			      || (enc_dbcs_new = atoi((char *)p_enc + 8)) == 0)
	    return e_invalid_argument;
#else
	// Unix: accept any "2byte-" name, assume current locale.
	enc_dbcs_new = DBCS_2BYTE;
#endif
    }
    else if ((idx = enc_canon_search(p_enc)) >= 0)
    {
	i = enc_canon_table[idx].prop;
	if (i & ENC_UNICODE)
	{
	    // Unicode
	    enc_utf8 = TRUE;
	    if (i & (ENC_2BYTE | ENC_2WORD))
		enc_unicode = 2;
	    else if (i & ENC_4BYTE)
		enc_unicode = 4;
	    else
		enc_unicode = 0;
	}
	else if (i & ENC_DBCS)
	{
	    // 2byte, handle below
	    enc_dbcs_new = enc_canon_table[idx].codepage;
	}
	else
	{
	    // Must be 8-bit.
	    enc_unicode = 0;
	    enc_utf8 = FALSE;
	}
    }
    else    // Don't know what encoding this is, reject it.
	return e_invalid_argument;

    if (enc_dbcs_new != 0)
    {
#ifdef MSWIN
	// Check if the DBCS code page is OK.
	if (!IsValidCodePage(enc_dbcs_new))
	    goto codepage_invalid;
#endif
	enc_unicode = 0;
	enc_utf8 = FALSE;
    }
    enc_dbcs = enc_dbcs_new;
    has_mbyte = (enc_dbcs != 0 || enc_utf8);

#if defined(MSWIN) || defined(FEAT_CYGWIN_WIN32_CLIPBOARD)
    enc_codepage = encname2codepage(p_enc);
    enc_latin9 = (STRCMP(p_enc, "iso-8859-15") == 0);
#endif

    // Detect an encoding that uses latin1 characters.
    enc_latin1like = (enc_utf8 || STRCMP(p_enc, "latin1") == 0
					|| STRCMP(p_enc, "iso-8859-15") == 0);

    /*
     * Set the function pointers.
     */
    if (enc_utf8)
    {
	mb_ptr2len = utfc_ptr2len;
	mb_ptr2len_len = utfc_ptr2len_len;
	mb_char2len = utf_char2len;
	mb_char2bytes = utf_char2bytes;
	mb_ptr2cells = utf_ptr2cells;
	mb_ptr2cells_len = utf_ptr2cells_len;
	mb_char2cells = utf_char2cells;
	mb_off2cells = utf_off2cells;
	mb_ptr2char = utf_ptr2char;
	mb_head_off = utf_head_off;
    }
    else if (enc_dbcs != 0)
    {
	mb_ptr2len = dbcs_ptr2len;
	mb_ptr2len_len = dbcs_ptr2len_len;
	mb_char2len = dbcs_char2len;
	mb_char2bytes = dbcs_char2bytes;
	mb_ptr2cells = dbcs_ptr2cells;
	mb_ptr2cells_len = dbcs_ptr2cells_len;
	mb_char2cells = dbcs_char2cells;
	mb_off2cells = dbcs_off2cells;
	mb_ptr2char = dbcs_ptr2char;
	mb_head_off = dbcs_head_off;
    }
    else
    {
	mb_ptr2len = latin_ptr2len;
	mb_ptr2len_len = latin_ptr2len_len;
	mb_char2len = latin_char2len;
	mb_char2bytes = latin_char2bytes;
	mb_ptr2cells = latin_ptr2cells;
	mb_ptr2cells_len = latin_ptr2cells_len;
	mb_char2cells = latin_char2cells;
	mb_off2cells = latin_off2cells;
	mb_ptr2char = latin_ptr2char;
	mb_head_off = latin_head_off;
    }

    /*
     * Fill the mb_bytelen_tab[] for MB_BYTE2LEN().
     */
#ifdef LEN_FROM_CONV
    // When 'encoding' is different from the current locale mblen() won't
    // work.  Use conversion to "utf-8" instead.
    vimconv.vc_type = CONV_NONE;
    if (enc_dbcs)
    {
	p = enc_locale();
	if (p == NULL || STRCMP(p, p_enc) != 0)
	{
	    convert_setup(&vimconv, p_enc, (char_u *)"utf-8");
	    vimconv.vc_fail = TRUE;
	}
	vim_free(p);
    }
#endif

    for (i = 0; i < 256; ++i)
    {
	// Our own function to reliably check the length of UTF-8 characters,
	// independent of mblen().
	if (enc_utf8)
	    n = utf8len_tab[i];
	else if (enc_dbcs == 0)
	    n = 1;
	else
	{
#if defined(MSWIN) || defined(WIN32UNIX)
	    // enc_dbcs is set by setting 'fileencoding'.  It becomes a Windows
	    // CodePage identifier, which we can pass directly in to Windows
	    // API
	    n = IsDBCSLeadByteEx(enc_dbcs, (WINBYTE)i) ? 2 : 1;
#else
# if defined(__amigaos4__) || defined(__ANDROID__) || \
				   !(defined(HAVE_MBLEN) || defined(X_LOCALE))
	    /*
	     * if mblen() is not available, character which MSB is turned on
	     * are treated as leading byte character. (note : This assumption
	     * is not always true.)
	     */
	    n = (i & 0x80) ? 2 : 1;
# else
	    char buf[MB_MAXBYTES + 1];

	    if (i == NUL)	// just in case mblen() can't handle ""
		n = 1;
	    else
	    {
		buf[0] = i;
		buf[1] = 0;
#  ifdef LEN_FROM_CONV
		if (vimconv.vc_type != CONV_NONE)
		{
		    /*
		     * string_convert() should fail when converting the first
		     * byte of a double-byte character.
		     */
		    p = string_convert(&vimconv, (char_u *)buf, NULL);
		    if (p != NULL)
		    {
			vim_free(p);
			n = 1;
		    }
		    else
			n = 2;
		}
		else
#  endif
		{
		    /*
		     * mblen() should return -1 for invalid (means the leading
		     * multibyte) character.  However there are some platforms
		     * where mblen() returns 0 for invalid character.
		     * Therefore, following condition includes 0.
		     */
		    vim_ignored = mblen(NULL, 0);  // First reset the state.
		    if (mblen(buf, (size_t)1) <= 0)
			n = 2;
		    else
			n = 1;
		}
	    }
# endif
#endif
	}

	mb_bytelen_tab[i] = n;
    }

#ifdef LEN_FROM_CONV
    convert_setup(&vimconv, NULL, NULL);
#endif

    // The cell width depends on the type of multi-byte characters.
    (void)init_chartab();

    // When enc_utf8 is set or reset, (de)allocate ScreenLinesUC[]
    screenalloc(FALSE);

    // When using Unicode, set default for 'fileencodings'.
    if (enc_utf8 && !option_was_set((char_u *)"fencs"))
	set_fencs_unicode();

#if defined(HAVE_BIND_TEXTDOMAIN_CODESET) && defined(FEAT_GETTEXT)
    // GNU gettext 0.10.37 supports this feature: set the codeset used for
    // translated messages independently from the current locale.
    (void)bind_textdomain_codeset(VIMPACKAGE,
					  enc_utf8 ? "utf-8" : (char *)p_enc);
#endif

#ifdef MSWIN
    // When changing 'encoding' while starting up, then convert the command
    // line arguments from the active codepage to 'encoding'.
    if (starting != 0)
	fix_arg_enc();
#endif

    // Fire an autocommand to let people do custom font setup. This must be
    // after Vim has been setup for the new encoding.
    apply_autocmds(EVENT_ENCODINGCHANGED, NULL, (char_u *)"", FALSE, curbuf);

#ifdef FEAT_SPELL
    // Need to reload spell dictionaries
    spell_reload();
#endif

    return NULL;
}