System.Uri.CheckKnownSchemes C# (CSharp) Method

        unsafe static private bool CheckKnownSchemes(long* lptr, ushort nChars, ref UriParser syntax)
        {
            //NOTE beware of too short input buffers!

            const long _HTTP_Mask0 = 'h' | ('t' << 16) | ((long)'t' << 32) | ((long)'p' << 48);
            const char _HTTPS_Mask1 = 's';
            const int _WS_Mask = 'w' | ('s' << 16);
            const long _WSS_Mask = 'w' | ('s' << 16) | ((long)'s' << 32) | ((long)':' << 48);
            const long _FTP_Mask = 'f' | ('t' << 16) | ((long)'p' << 32) | ((long)':' << 48);
            const long _FILE_Mask0 = 'f' | ('i' << 16) | ((long)'l' << 32) | ((long)'e' << 48);
            const long _GOPHER_Mask0 = 'g' | ('o' << 16) | ((long)'p' << 32) | ((long)'h' << 48);
            const int _GOPHER_Mask1 = 'e' | ('r' << 16);
            const long _MAILTO_Mask0 = 'm' | ('a' << 16) | ((long)'i' << 32) | ((long)'l' << 48);
            const int _MAILTO_Mask1 = 't' | ('o' << 16);
            const long _NEWS_Mask0 = 'n' | ('e' << 16) | ((long)'w' << 32) | ((long)'s' << 48);
            const long _NNTP_Mask0 = 'n' | ('n' << 16) | ((long)'t' << 32) | ((long)'p' << 48);
            const long _UUID_Mask0 = 'u' | ('u' << 16) | ((long)'i' << 32) | ((long)'d' << 48);

            const long _TELNET_Mask0 = 't' | ('e' << 16) | ((long)'l' << 32) | ((long)'n' << 48);
            const int _TELNET_Mask1 = 'e' | ('t' << 16);

            const long _NETXXX_Mask0 = 'n' | ('e' << 16) | ((long)'t' << 32) | ((long)'.' << 48);
            const long _NETTCP_Mask1 = 't' | ('c' << 16) | ((long)'p' << 32) | ((long)':' << 48);
            const long _NETPIPE_Mask1 = 'p' | ('i' << 16) | ((long)'p' << 32) | ((long)'e' << 48);

            const long _LDAP_Mask0 = 'l' | ('d' << 16) | ((long)'a' << 32) | ((long)'p' << 48);


            const long _LOWERCASE_Mask = 0x0020002000200020L;
            const int _INT_LOWERCASE_Mask = 0x00200020;

            if (nChars == 2)
            {
                // This is the only known scheme of length 2
                if ((((int)*lptr) | _INT_LOWERCASE_Mask) == _WS_Mask)
                {
                    syntax = UriParser.WsUri;
                    return true;
                }
                return false;
            }

            //Map to a known scheme if possible
            //upgrade 4 letters to ASCII lower case, keep a false case to stay false
            switch (*lptr | _LOWERCASE_Mask)
            {
                case _HTTP_Mask0:
                    if (nChars == 4)
                    {
                        syntax = UriParser.HttpUri;
                        return true;
                    }
                    if (nChars == 5 && ((*(char*)(lptr + 1)) | 0x20) == _HTTPS_Mask1)
                    {
                        syntax = UriParser.HttpsUri;
                        return true;
                    }
                    break;
                case _WSS_Mask:
                    if (nChars == 3)
                    {
                        syntax = UriParser.WssUri;
                        return true;
                    }
                    break;
                case _FILE_Mask0:
                    if (nChars == 4)
                    {
                        syntax = UriParser.FileUri;
                        return true;
                    }
                    break;
                case _FTP_Mask:
                    if (nChars == 3)
                    {
                        syntax = UriParser.FtpUri;
                        return true;
                    }
                    break;

                case _NEWS_Mask0:
                    if (nChars == 4)
                    {
                        syntax = UriParser.NewsUri;
                        return true;
                    }
                    break;

                case _NNTP_Mask0:
                    if (nChars == 4)
                    {
                        syntax = UriParser.NntpUri;
                        return true;
                    }
                    break;

                case _UUID_Mask0:
                    if (nChars == 4)
                    {
                        syntax = UriParser.UuidUri;
                        return true;
                    }
                    break;

                case _GOPHER_Mask0:
                    if (nChars == 6 && (*(int*)(lptr + 1) | _INT_LOWERCASE_Mask) == _GOPHER_Mask1)
                    {
                        syntax = UriParser.GopherUri;
                        return true;
                    }
                    break;
                case _MAILTO_Mask0:
                    if (nChars == 6 && (*(int*)(lptr + 1) | _INT_LOWERCASE_Mask) == _MAILTO_Mask1)
                    {
                        syntax = UriParser.MailToUri;
                        return true;
                    }
                    break;

                case _TELNET_Mask0:
                    if (nChars == 6 && (*(int*)(lptr + 1) | _INT_LOWERCASE_Mask) == _TELNET_Mask1)
                    {
                        syntax = UriParser.TelnetUri;
                        return true;
                    }
                    break;

                case _NETXXX_Mask0:
                    if (nChars == 8 && (*(lptr + 1) | _LOWERCASE_Mask) == _NETPIPE_Mask1)
                    {
                        syntax = UriParser.NetPipeUri;
                        return true;
                    }
                    else if (nChars == 7 && (*(lptr + 1) | _LOWERCASE_Mask) == _NETTCP_Mask1)
                    {
                        syntax = UriParser.NetTcpUri;
                        return true;
                    }
                    break;

                case _LDAP_Mask0:
                    if (nChars == 4)
                    {
                        syntax = UriParser.LdapUri;
                        return true;
                    }
                    break;
                default: break;
            }
            return false;
        }