crc32

crc32

https://pkg.go.dev/hash/crc32@go1.20.1

Package crc32 implements the 32-bit cyclic redundancy check, or CRC-32, checksum. See https://en.wikipedia.org/wiki/Cyclic_redundancy_check for information.

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

See https://en.wikipedia.org/wiki/Mathematics_of_cyclic_redundancy_checks#Reversed_representations_and_reciprocal_polynomials for information.

常量

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const (
	// IEEE is by far and away the most common CRC-32 polynomial.
	// Used by ethernet (IEEE 802.3), v.42, fddi, gzip, zip, png, ...
	IEEE = 0xedb88320

	// Castagnoli's polynomial, used in iSCSI.
	// Has better error detection characteristics than IEEE.
	// https://dx.doi.org/10.1109/26.231911
	Castagnoli = 0x82f63b78

	// Koopman's polynomial.
	// Also has better error detection characteristics than IEEE.
	// https://dx.doi.org/10.1109/DSN.2002.1028931
	Koopman = 0xeb31d82e
)

Predefined polynomials.

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const Size = 4

The size of a CRC-32 checksum in bytes.

变量

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var IEEETable = simpleMakeTable(IEEE)

IEEETable is the table for the IEEE polynomial.

函数

func Checksum

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func Checksum(data []byte, tab *Table) uint32

Checksum returns the CRC-32 checksum of data using the polynomial represented by the Table.

func ChecksumIEEE

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func ChecksumIEEE(data []byte) uint32

ChecksumIEEE returns the CRC-32 checksum of data using the IEEE polynomial.

func New

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func New(tab *Table) hash.Hash32

New creates a new hash.Hash32 computing the CRC-32 checksum using the polynomial represented by the Table. Its Sum method will lay the value out in big-endian byte order. The returned Hash32 also implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to marshal and unmarshal the internal state of the hash.

func NewIEEE

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func NewIEEE() hash.Hash32

NewIEEE creates a new hash.Hash32 computing the CRC-32 checksum using the IEEE polynomial. Its Sum method will lay the value out in big-endian byte order. The returned Hash32 also implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to marshal and unmarshal the internal state of the hash.

func Update

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func Update(crc uint32, tab *Table, p []byte) uint32

Update returns the result of adding the bytes in p to the crc.

类型

type Table

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type Table [256]uint32

Table is a 256-word table representing the polynomial for efficient processing.

func MakeTable

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func MakeTable(poly uint32) *Table

MakeTable returns a Table constructed from the specified polynomial. The contents of this Table must not be modified.