gcc/libgo/go/hash/crc32/example_test.go
Ian Lance Taylor fcee603081 libgo: compile examples in _test packages
Previously if the only names defined by _test packages were examples,
    the gotest script would emit an incorrect _testmain.go file.
    I worked around that by marking the example_test.go files +build ignored.
    
    This CL changes the gotest script to handle this case correctly,
    and removes the now-unnecessary build tags.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/214039

From-SVN: r280085
2020-01-09 23:14:57 +00:00

29 lines
1.0 KiB
Go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package crc32_test
import (
"fmt"
"hash/crc32"
)
func ExampleMakeTable() {
// 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
}