private string doReadString()

in src/nms-api/Util/EndianBinaryReader.cs [193:259]
58 lines of code
12 McCabe index (conditional complexity)

        private string doReadString(int utfLength)
        {
            char[] result = new char[utfLength];
            byte[] buffer = new byte[utfLength];

            int bytesRead = 0;
            while (bytesRead < utfLength)
            {
                int rc = Read(buffer, bytesRead, utfLength - bytesRead);
                if (rc == 0)
                {
                    throw new IOException("premature end of stream");
                }

                bytesRead += rc;
            }

            int count = 0;
            int index = 0;
            byte a = 0;

            while (count < utfLength)
            {
                if ((result[index] = (char) buffer[count++]) < 0x80)
                {
                    index++;
                }
                else if (((a = (byte) result[index]) & 0xE0) == 0xC0)
                {
                    if (count >= utfLength)
                    {
                        throw new IOException("Invalid UTF-8 encoding found, start of two byte char found at end.");
                    }

                    byte b = buffer[count++];
                    if ((b & 0xC0) != 0x80)
                    {
                        throw new IOException("Invalid UTF-8 encoding found, byte two does not start with 0x80.");
                    }

                    result[index++] = (char) (((a & 0x1F) << 6) | (b & 0x3F));
                }
                else if ((a & 0xF0) == 0xE0)
                {
                    if (count + 1 >= utfLength)
                    {
                        throw new IOException("Invalid UTF-8 encoding found, start of three byte char found at end.");
                    }

                    byte b = buffer[count++];
                    byte c = buffer[count++];
                    if (((b & 0xC0) != 0x80) || ((c & 0xC0) != 0x80))
                    {
                        throw new IOException("Invalid UTF-8 encoding found, byte two does not start with 0x80.");
                    }

                    result[index++] = (char) (((a & 0x0F) << 12) |
                                              ((b & 0x3F) << 6) | (c & 0x3F));
                }
                else
                {
                    throw new IOException("Invalid UTF-8 encoding found, aborting.");
                }
            }

            return new String(result, 0, index);
        }