Convert UTF-8 string to ANSI

// Converting UTF-8 symbols to ANSI

stock ConvertUTF8ToANSI(const utf8str[])
{
    new ansistr[1024], i = 0, j = 0;
    while(utf8str[i] != 0 && j < sizeof(ansistr) - 1)
    {
        if((utf8str[i] & 0x80) == 0) ansistr[j++] = utf8str[i++];
        else if((utf8str[i] & 0xE0) == 0xC0)
        {
            new symbol = ((utf8str[i] & 0x1F) << 6) | (utf8str[i + 1] & 0x3F);
            switch(symbol)
            {
                case 0x0410..0x044F: ansistr[j++] = symbol - 0x0350;
                default: ansistr[j++] = '?';
            }
            i += 2;
        }
        else if((utf8str[i] & 0xF0) == 0xE0 || (utf8str[i] & 0xF8) == 0xF0) i += (utf8str[i] & 0xF0) == 0xE0 ? 3 : 4;
        else i++;
    }
    ansistr[j] = 0;
    return ansistr;
}