github.com/MangoDowner/go-gm@v0.0.0-20180818020936-8baa2bd4408c/src/hash/crc32/example_test.go (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package crc32_test
     6  
     7  import (
     8  	"fmt"
     9  	"hash/crc32"
    10  )
    11  
    12  func ExampleMakeTable() {
    13  	// In this package, the CRC polynomial is represented in reversed notation,
    14  	// or LSB-first representation.
    15  	//
    16  	// LSB-first representation is a hexadecimal number with n bits, in which the
    17  	// most significant bit represents the coefficient of x⁰ and the least significant
    18  	// bit represents the coefficient of xⁿ⁻¹ (the coefficient for xⁿ is implicit).
    19  	//
    20  	// For example, CRC32-Q, as defined by the following polynomial,
    21  	//	x³²+ x³¹+ x²⁴+ x²²+ x¹⁶+ x¹⁴+ x⁸+ x⁷+ x⁵+ x³+ x¹+ x⁰
    22  	// has the reversed notation 0b11010101100000101000001010000001, so the value
    23  	// that should be passed to MakeTable is 0xD5828281.
    24  	crc32q := crc32.MakeTable(0xD5828281)
    25  	fmt.Printf("%08x\n", crc32.Checksum([]byte("Hello world"), crc32q))
    26  	// Output:
    27  	// 2964d064
    28  }