package Common import ( "bytes" "encoding/binary" "io" "log" ) // StreamReader allows you to read data from a byte array in various formats type StreamReader struct { data []byte position uint64 } // CreateStreamReader creates an instance of the stream reader func CreateStreamReader(source []byte) *StreamReader { result := &StreamReader{ data: source, position: 0, } return result } // GetPosition returns the current stream position func (v *StreamReader) GetPosition() uint64 { return v.position } // GetSize returns the total size of the stream in bytes func (v *StreamReader) GetSize() uint64 { return uint64(len(v.data)) } // GetByte returns a byte from the stream func (v *StreamReader) GetByte() byte { result := v.data[v.position] v.position++ return result } // GetUInt16 returns a uint16 word from the stream func (v *StreamReader) GetUInt16() uint16 { result := uint16(v.data[v.position]) result += uint16(v.data[v.position+1]) << 8 v.position += 2 return result } // GetInt16 returns a int16 word from the stream func (v *StreamReader) GetInt16() int16 { var result int16 err := binary.Read(bytes.NewReader([]byte{v.data[v.position], v.data[v.position+1]}), binary.LittleEndian, &result) if err != nil { log.Panic(err) } v.position += 2 return result } func (v *StreamReader) SetPosition(newPosition uint64) { v.position = newPosition } // GetUInt32 returns a uint32 word from the stream func (v *StreamReader) GetUInt32() uint32 { var result uint32 err := binary.Read(bytes.NewReader( []byte{ v.data[v.position], v.data[v.position+1], v.data[v.position+2], v.data[v.position+3], }), binary.LittleEndian, &result) if err != nil { log.Panic(err) } v.position += 4 return result } // GetInt32 returns an int32 word from the stream func (v *StreamReader) GetInt32() int32 { var result int32 err := binary.Read(bytes.NewReader( []byte{ v.data[v.position], v.data[v.position+1], v.data[v.position+2], v.data[v.position+3], }), binary.LittleEndian, &result) if err != nil { log.Panic(err) } v.position += 4 return result } // ReadByte implements io.ByteReader func (v *StreamReader) ReadByte() (byte, error) { return v.GetByte(), nil } // ReadBytes reads multiple bytes func (v *StreamReader) ReadBytes(count int) ([]byte, error) { result := make([]byte, count) for i := 0; i < count; i++ { result[i] = v.GetByte() } return result, nil } func (v *StreamReader) SkipBytes(count int) { v.position += uint64(count) } // Read implements io.Reader func (v *StreamReader) Read(p []byte) (n int, err error) { streamLength := v.GetSize() for i := 0; ; i++ { if v.GetPosition() >= streamLength { return i, io.EOF } if i >= len(p) { return i, nil } p[i] = v.GetByte() } } func (v *StreamReader) Eof() bool { return v.position >= uint64(len(v.data)) }