From 82ba818ff456bcd6d56a06226e3f27e98fbb55c3 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Thu, 14 Aug 2025 22:58:58 -0500 Subject: removing all downloaded devdocs files --- devdocs/go/hash%2Fcrc32%2Findex.html | 62 ------------------------------------ 1 file changed, 62 deletions(-) delete mode 100644 devdocs/go/hash%2Fcrc32%2Findex.html (limited to 'devdocs/go/hash%2Fcrc32%2Findex.html') diff --git a/devdocs/go/hash%2Fcrc32%2Findex.html b/devdocs/go/hash%2Fcrc32%2Findex.html deleted file mode 100644 index 65aed1328..000000000 --- a/devdocs/go/hash%2Fcrc32%2Findex.html +++ /dev/null @@ -1,62 +0,0 @@ -

Package crc32

Overview

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

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

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

Index

Examples

MakeTable

Package files

crc32.go crc32_amd64.go crc32_generic.go

Constants

Predefined polynomials.

-
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
-)

The size of a CRC-32 checksum in bytes.

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const Size = 4

Variables

IEEETable is the table for the IEEE polynomial.

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var IEEETable = simpleMakeTable(IEEE)

func Checksum 

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

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

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func ChecksumIEEE 

func ChecksumIEEE(data []byte) uint32

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

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func New 

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.

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func NewIEEE 

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.

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func Update 

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

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

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type Table

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

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type Table [256]uint32

func MakeTable 

func MakeTable(poly uint32) *Table

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

Example -

Code:

// 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))
-

Output:

2964d064
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-

- © Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
- http://golang.org/pkg/hash/crc32/ -

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