lzw

Documentation

Overview

Package lzw implements the Lempel-Ziv-Welch compressed data format, described in T. A. Welch, “A Technique for High-Performance Data Compression”, Computer, 17(6) (June 1984), pp 8-19.

In particular, it implements LZW as used by the GIF, TIFF and PDF file formats, which means variable-width codes up to 12 bits and the first two non-literal codes are a clear code and an EOF code.

Index

• func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser
• func NewWriter(w io.Writer, order Order, litWidth int) io.WriteCloser
• type Order

Functions

func NewReader

func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser

NewReader creates a new io.ReadCloser that satisfies reads by decompressing the data read from r. It is the caller's responsibility to call Close on the ReadCloser when finished reading. The number of bits to use for literal codes, litWidth, must be in the range [2,8] and is typically 8.

func NewWriter

func NewWriter(w io.Writer, order Order, litWidth int) io.WriteCloser

NewWriter creates a new io.WriteCloser that satisfies writes by compressing the data and writing it to w. It is the caller's responsibility to call Close on the WriteCloser when finished writing. The number of bits to use for literal codes, litWidth, must be in the range [2,8] and is typically 8.

Types

type Order

type Order int

Order specifies the bit ordering in an LZW data stream.

const (
	// LSB means Least Significant Bits first, as used in the GIF file format.
	LSB Order = iota
	// MSB means Most Significant Bits first, as used in the TIFF and PDF
	// file formats.
	MSB
)