SharpCifs.Smb.SmbFile.QueryLookup C# (CSharp) Method

        internal static string QueryLookup(string query, string param)
        {
            char[] instr = query.ToCharArray();
            int i;
            int ch;
            int st;
            int eq;
            st = eq = 0;
            for (i = 0; i < instr.Length; i++)
            {
                ch = instr[i];
                if (ch == '&')
                {
                    if (eq > st)
                    {
                        string p = new string(instr, st, eq - st);
                        if (Runtime.EqualsIgnoreCase(p, param))
                        {
                            eq++;
                            return new string(instr, eq, i - eq);
                        }
                    }
                    st = i + 1;
                }
                else
                {
                    if (ch == '=')
                    {
                        eq = i;
                    }
                }
            }
            if (eq > st)
            {
                string p = new string(instr, st, eq - st);
                if (Runtime.EqualsIgnoreCase(p, param))
                {
                    eq++;
                    return new string(instr, eq, instr.Length - eq);
                }
            }
            return null;
        }