crc64

Documentation

Overview

Package crc64 implements the 64-bit cyclic redundancy check, or CRC-64, checksum. See https://en.wikipedia.org/wiki/Cyclic_redundancy_check for information.

Polynomials are represented in LSB-first form, also known as reversed representation.

Checksums are layed out in big-endian byte order.

Index

• Constants
• type Hash
  • func New(p *Poly) Hash
• type Poly
  • func ECMA() *Poly
  • func ISO() *Poly
  • func MakePoly(poly uint64) *Poly
  • func (p *Poly) Checksum(data []byte) uint64
  • func (p *Poly) Combine(prev, next uint64, n int64) uint64
  • func (p *Poly) Polynomial() uint64
  • func (p *Poly) Update(sum uint64, data []byte) uint64

Constants

const Size = 8

The size of a CRC-64 checksum in bytes.

Types

type Hash

type Hash interface {
	hash.Hash64
	encoding.BinaryMarshaler
	encoding.BinaryUnmarshaler
}

Hash is a hash.Hash64 that also implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to marshal and unmarshal the internal state of the hash. Its Sum methods will lay the value out in big-endian byte order.

func New

func New(p *Poly) Hash

New creates a new Hash computing the CRC-64 checksum using the polynomial represented by the Poly.

type Poly

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

Poly represents a 64-bit polynomial with tables for efficient processing.

func ECMA

func ECMA() *Poly

ECMA returns the Poly representing the ECMA polynomial, defined in ECMA 182.

func ISO

func ISO() *Poly

ISO returns the Poly representing the ISO polynomial, defined in ISO 3309 and used in HDLC.

func MakePoly

func MakePoly(poly uint64) *Poly

MakePoly returns a Poly constructed from the specified polynomial given in LSB-first form, also known as reversed representation. The returned Poly may be shared and must not be modified.

func (*Poly) Checksum

func (p *Poly) Checksum(data []byte) uint64

Checksum returns the CRC-64 checksum of data in big-endian byte order.

func (*Poly) Combine

func (p *Poly) Combine(prev, next uint64, n int64) uint64

Combine returns the result of adding n bytes with the next sum to the prev sum.

func (*Poly) Polynomial

func (p *Poly) Polynomial() uint64

Polynomial returns the polynomial in LSB-first form, also known as reversed representation.

func (*Poly) Update

func (p *Poly) Update(sum uint64, data []byte) uint64

Update returns the result of adding the bytes in data to the sum.