compression

Documentation

Index

• Constants
• Variables
• func AppendVarint(buf []byte, x int) []byte
• func PutVarint(buf []byte, x int) int
• func ReadVarint(r io.ByteReader) (int, error)
• func Varint(buf []byte) (i int, n int)
• type Huffman
  • func NewHuffman(frequencyTable [HuffmanMaxSymbols]uint32) *Huffman
  • func (h *Huffman) Compress(data, compressed []byte) (written int, err error)
  • func (h *Huffman) Decompress(data, decompressed []byte) (written int, err error)
• type MsgPacker
  • func NewMsgPacker(msgType protocol.MsgType, system ...bool) *MsgPacker
• type Packer
  • func NewPacker(buf ...[]byte) *Packer
  • func (p *Packer) AddByte(b byte)
  • func (p *Packer) AddBytes(data []byte)
  • func (p *Packer) AddInt(i int)
  • func (p *Packer) AddString(s string)
  • func (p *Packer) Bytes() []byte
  • func (p *Packer) Reset()
  • func (p *Packer) Size() int
• type Unpacker
  • func NewUnpacker(data []byte) *Unpacker
  • func (u *Unpacker) Bytes() []byte
  • func (u *Unpacker) NextByte() (b byte, err error)
  • func (u *Unpacker) NextBytes(size int) (b []byte, err error)
  • func (u *Unpacker) NextInt() (i int, err error)
  • func (u *Unpacker) NextString() (s string, err error)
  • func (u *Unpacker) Reset(b []byte)
  • func (u *Unpacker) Size() int

Constants

const (
	HuffmanEOFSymbol  = protocol.HuffmanEOFSymbol
	HuffmanMaxSymbols = protocol.HuffmanMaxSymbols

	HuffmanMaxNodes        = (HuffmanMaxSymbols)*2 + 1 // +1 for additional EOF symbol
	HuffmanLookupTableBits = 10
	HuffmanLookupTableSize = (1 << HuffmanLookupTableBits)
	HuffmanLookupTableMask = (HuffmanLookupTableSize - 1)
)

const (
	// StringTerminator is the zero byte that terminates the string
	StringTerminator byte = 0

	// with how many bytes the packer is initialized
	PackerBufferSize = 1024 * 2
)

const (
	// max bytes that can be received for one integer
	MaxVarintLen32 = 5
)

Variables

var (
	ErrHuffmanCompress   = errors.New("compression error")
	ErrHuffmanDecompress = errors.New("decompression error")
)

var (
	// ErrNoDataToUnpack is returned if the compressed array does not have sufficient data to unpack
	ErrNoDataToUnpack = fmt.Errorf("%w: no data", io.EOF)

	// ErrNotAString if no separator after a string is found, the string cannot be unpacked, as there is no string
	ErrNotAString = errors.New("could not unpack string: terminator not found")

	// ErrNotEnoughData is used when the user tries to retrieve more data with NextBytes() than there is available.
	ErrNotEnoughData = errors.New("trying to read more data than available")
)

Functions

func AppendVarint

func AppendVarint(buf []byte, x int) []byte

AppendVarint appends the varint-encoded form of x, as generated by PutVarint, to buf and returns the extended buffer.

func PutVarint

func PutVarint(buf []byte, x int) int

PutVarint encodes an int32 into buf and returns the number of bytes written. If the buffer is too small, PutVarint will panic. Format: ESDDDDDD EDDDDDDD EDD... Extended, Data, Sign E: is next byte part of the current integer S: Sign of integer Data, Integer bits that follow the sign

func ReadVarint

func ReadVarint(r io.ByteReader) (int, error)

ReadVarint can decode a stream of bytes

func Varint

func Varint(buf []byte) (i int, n int)

Varint decodes an int from buf and returns that value and the number of bytes read (> 0). If an error occurred, the value is 0 and the number of bytes n is <= 0 with the following meaning:

n == 0: buf too small
n  < 0: value larger than 32 bits (overflow)
        and -n is the number of bytes read

Types

type Huffman

type Huffman struct {
	// contains filtered or unexported fields
}

func NewHuffman

func NewHuffman(frequencyTable [HuffmanMaxSymbols]uint32) *Huffman

NewHuffman expects a frequency table aka index -> symbol You can use the default one that can be found under protocol.FrequencyTable You can put the frequency at index HuffmanMaxSymbols -1 to the value 1. It is the EOF value which will ne overwritten anyway.

func (*Huffman) Compress

func (h *Huffman) Compress(data, compressed []byte) (written int, err error)

Compress compresses in data to the compressed slice. 'compressed' must be preallocated with enough space to fit the result.

func (*Huffman) Decompress

func (h *Huffman) Decompress(data, decompressed []byte) (written int, err error)

Decompress decompresses 'data' and writes the result into 'decompressed'. The decompressed slice must be preallocated to fit the decompressed data.

type MsgPacker

type MsgPacker struct {
	Packer
}

func NewMsgPacker

func NewMsgPacker(msgType protocol.MsgType, system ...bool) *MsgPacker

NewMsgPacker creates a new message packer It initially sets the message type header and system flag

type Packer

type Packer struct {
	// contains filtered or unexported fields
}

Packer compresses data

func NewPacker

func NewPacker(buf ...[]byte) *Packer

NewPacker ceates a new Packer with a given default buffer size. You can provide ONE optional buffer that is used instead of the default one

func (*Packer) AddByte

func (p *Packer) AddByte(b byte)

func (*Packer) AddBytes

func (p *Packer) AddBytes(data []byte)

func (*Packer) AddInt

func (p *Packer) AddInt(i int)

func (*Packer) AddString

func (p *Packer) AddString(s string)

func (*Packer) Bytes

func (p *Packer) Bytes() []byte

Bytes returns the underlying buffer

func (*Packer) Reset

func (p *Packer) Reset()

Reset internal buffer

func (*Packer) Size

func (p *Packer) Size() int

Size len of the Buffer

type Unpacker

type Unpacker struct {
	// contains filtered or unexported fields
}

Unpacker unpacks received messages

func NewUnpacker

func NewUnpacker(data []byte) *Unpacker

NewUnpacker constructs a new Unpacker

func (*Unpacker) Bytes

func (u *Unpacker) Bytes() []byte

Bytes returns the not yet used bytes. This operation consumes the buffer leaving it empty

func (*Unpacker) NextByte

func (u *Unpacker) NextByte() (b byte, err error)

NextByte returns the next bytes.

func (*Unpacker) NextBytes

func (u *Unpacker) NextBytes(size int) (b []byte, err error)

NextBytes returns the next size bytes.

func (*Unpacker) NextInt

func (u *Unpacker) NextInt() (i int, err error)

NextInt unpacks the next integer

func (*Unpacker) NextString

func (u *Unpacker) NextString() (s string, err error)

NextString unpacks the next string from the message

func (*Unpacker) Reset

func (u *Unpacker) Reset(b []byte)

Reset resets the underlying byte slice to a new slice

func (*Unpacker) Size

func (u *Unpacker) Size() int

Size of the underlying buffer