package crc32

Import Path
	hash/crc32 (on golang.org and go.dev)

Dependency Relation
	imports 6 packages, and imported by 2 packages


Involved Source Files

	
		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.

	      crc32_amd64.go
	      crc32_generic.go
	      crc32_amd64.s


Code Examples

	
		package main
		
		import (
			"fmt"
			"hash/crc32"
		)
		
		func main() {
			// In this package, the CRC polynomial is represented in reversed notation,
			// or LSB-first representation.
			//
			// LSB-first representation is a hexadecimal number with n bits, in which the
			// most significant bit represents the coefficient of x⁰ and the least significant
			// bit represents the coefficient of xⁿ⁻¹ (the coefficient for xⁿ is implicit).
			//
			// For example, CRC32-Q, as defined by the following polynomial,
			//	x³²+ x³¹+ x²⁴+ x²²+ x¹⁶+ x¹⁴+ x⁸+ x⁷+ x⁵+ x³+ x¹+ x⁰
			// has the reversed notation 0b11010101100000101000001010000001, so the value
			// that should be passed to MakeTable is 0xD5828281.
			crc32q := crc32.MakeTable(0xD5828281)
			fmt.Printf("%08x\n", crc32.Checksum([]byte("Hello world"), crc32q))
		}




Package-Level Type Names (total 4, in which 1 are exported)


	/* sort exporteds by:  |  */
	
		Table is a 256-word table representing the polynomial for efficient processing.

		
			func MakeTable(poly uint32) *Table
			
		
			func Checksum(data []byte, tab *Table) uint32
			func New(tab *Table) hash.Hash32
			func Update(crc uint32, tab *Table, p []byte) uint32
			
		
			  var IEEETable *Table
			


	


Package-Level Functions (total 26, in which 6 are exported)


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


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


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


	
		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.


	
		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.


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


	


Package-Level Variables (total 14, in which 1 are exported)


	
		IEEETable is the table for the IEEE polynomial.


	


Package-Level Constants (total 9, in which 4 are exported)


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


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


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


	
		The size of a CRC-32 checksum in bytes.