Question

我获取了并cksum复制了多项式。这与 Go 标准库中定义的预定义 IEEE 变体相同。

package main

import (
    "fmt"
    "hash/crc32"
)

// https://github.com/coreutils/coreutils/blob/a9b78541fa7c06567c5b82fb4e89d85a1dc0c611/src/cksum.c#L54
//
//          32   26   23   22   16   12   11   10   8   7   5   4   2   1
//    G(X)=X  + X  + X  + X  + X  + X  + X  + X  + X + X + X + X + X + X + 1

const p = 0b11101101101110001000001100100000

func main() {
    cksum := crc32.MakeTable(p)
    fmt.Println(crc32.Checksum([]byte("moin"), cksum))
    fmt.Println(crc32.ChecksumIEEE([]byte("moin")))
}

结果是：

但是当我在 Debian 12 (coreutils 9.1) 上使用时，cksum结果是另外一回事：

$ printf "moin" | cksum 
1401816862 4

这里有什么问题吗？

更新

我想问题就解释。

但问题仍然是：如何与“hash/crc32”一样做cksum？

。

您想在这里“修复”哪一个？从man cksum你想要-o 3得到一个“32位CRC”来匹配Go版本。 — 
抱歉，放弃旧的 bsd 版本可能有所不同。我没有方便测试的 Linux 系统，但您可以尝试一些不同的算法。 —

Accepted Answer

上的 CRC-32/CKSUM 参数

width=32 poly=0x04c11db7 init=0x00000000 refin=false refout=false xorout=0xffffffff check=0x765e7680 residue=0xc704dd7b name="CRC-32/CKSUM"

并与 CRC-32/ISO-HDLC 的参数进行比较，我相信它对应于 hash/crc32 中的算法：

width=32 poly=0x04c11db7 init=0xffffffff refin=true refout=true xorout=0xffffffff check=0xcbf43926 residue=0xdebb20e3 name="CRC-32/ISO-HDLC"

只能调整hash/crc32 中的poly（多项式），而不能调整init（初始值）、refin（反映输入）或refout（反映输出）。

除了这些参数之外，cksum 程序还处理输入后的输入流长度的表示。

是一些简单的代码，可以使用 hash/crc32 生成预期的输出。快速/真实的实现将从多项式创建另一个表。

很高兴知道这一点并且它回答了问题，但不幸的是这并不实用，它甚至比 OpenGroup 参考还要慢。 — 
@ceving 这是一个生成自定义表的解决方案，以避免反映每个输入字节。它应该更快，但是像这样的自定义表仍然无法从架构特定的优化中受益。 —

Answer 2

那就是：

width=32 poly=0x04c11db7 init=0x00000000 refin=false refout=false xorout=0xffffffff check=0x765e7680 residue=0xc704dd7b name="CRC-32/CKSUM"

该 CRC 向上移动（refin 和 refout false），而 Go hash/crc32 包似乎只支持向下移动的 CRC（refin 和 refout true）。您必须编写自己的 CRC 代码。

以下是 C 语言的示例，您可以将其转换为 Go：

#include <stddef.h>
#include <stdint.h>

static uint32_t const table_byte[] = {
    0xb1f7404b, 0xb5365dfc, 0xb8757b25, 0xbcb46692, 0xa2f33697, 0xa6322b20,
    0xab710df9, 0xafb0104e, 0x97ffadf3, 0x933eb044, 0x9e7d969d, 0x9abc8b2a,
    0x84fbdb2f, 0x803ac698, 0x8d79e041, 0x89b8fdf6, 0xfde69b3b, 0xf927868c,
    0xf464a055, 0xf0a5bde2, 0xeee2ede7, 0xea23f050, 0xe760d689, 0xe3a1cb3e,
    0xdbee7683, 0xdf2f6b34, 0xd26c4ded, 0xd6ad505a, 0xc8ea005f, 0xcc2b1de8,
    0xc1683b31, 0xc5a92686, 0x29d4f6ab, 0x2d15eb1c, 0x2056cdc5, 0x2497d072,
    0x3ad08077, 0x3e119dc0, 0x3352bb19, 0x3793a6ae, 0x0fdc1b13, 0x0b1d06a4,
    0x065e207d, 0x029f3dca, 0x1cd86dcf, 0x18197078, 0x155a56a1, 0x119b4b16,
    0x65c52ddb, 0x6104306c, 0x6c4716b5, 0x68860b02, 0x76c15b07, 0x720046b0,
    0x7f436069, 0x7b827dde, 0x43cdc063, 0x470cddd4, 0x4a4ffb0d, 0x4e8ee6ba,
    0x50c9b6bf, 0x5408ab08, 0x594b8dd1, 0x5d8a9066, 0x8571303c, 0x81b02d8b,
    0x8cf30b52, 0x883216e5, 0x967546e0, 0x92b45b57, 0x9ff77d8e, 0x9b366039,
    0xa379dd84, 0xa7b8c033, 0xaafbe6ea, 0xae3afb5d, 0xb07dab58, 0xb4bcb6ef,
    0xb9ff9036, 0xbd3e8d81, 0xc960eb4c, 0xcda1f6fb, 0xc0e2d022, 0xc423cd95,
    0xda649d90, 0xdea58027, 0xd3e6a6fe, 0xd727bb49, 0xef6806f4, 0xeba91b43,
    0xe6ea3d9a, 0xe22b202d, 0xfc6c7028, 0xf8ad6d9f, 0xf5ee4b46, 0xf12f56f1,
    0x1d5286dc, 0x19939b6b, 0x14d0bdb2, 0x1011a005, 0x0e56f000, 0x0a97edb7,
    0x07d4cb6e, 0x0315d6d9, 0x3b5a6b64, 0x3f9b76d3, 0x32d8500a, 0x36194dbd,
    0x285e1db8, 0x2c9f000f, 0x21dc26d6, 0x251d3b61, 0x51435dac, 0x5582401b,
    0x58c166c2, 0x5c007b75, 0x42472b70, 0x468636c7, 0x4bc5101e, 0x4f040da9,
    0x774bb014, 0x738aada3, 0x7ec98b7a, 0x7a0896cd, 0x644fc6c8, 0x608edb7f,
    0x6dcdfda6, 0x690ce011, 0xd8fba0a5, 0xdc3abd12, 0xd1799bcb, 0xd5b8867c,
    0xcbffd679, 0xcf3ecbce, 0xc27ded17, 0xc6bcf0a0, 0xfef34d1d, 0xfa3250aa,
    0xf7717673, 0xf3b06bc4, 0xedf73bc1, 0xe9362676, 0xe47500af, 0xe0b41d18,
    0x94ea7bd5, 0x902b6662, 0x9d6840bb, 0x99a95d0c, 0x87ee0d09, 0x832f10be,
    0x8e6c3667, 0x8aad2bd0, 0xb2e2966d, 0xb6238bda, 0xbb60ad03, 0xbfa1b0b4,
    0xa1e6e0b1, 0xa527fd06, 0xa864dbdf, 0xaca5c668, 0x40d81645, 0x44190bf2,
    0x495a2d2b, 0x4d9b309c, 0x53dc6099, 0x571d7d2e, 0x5a5e5bf7, 0x5e9f4640,
    0x66d0fbfd, 0x6211e64a, 0x6f52c093, 0x6b93dd24, 0x75d48d21, 0x71159096,
    0x7c56b64f, 0x7897abf8, 0x0cc9cd35, 0x0808d082, 0x054bf65b, 0x018aebec,
    0x1fcdbbe9, 0x1b0ca65e, 0x164f8087, 0x128e9d30, 0x2ac1208d, 0x2e003d3a,
    0x23431be3, 0x27820654, 0x39c55651, 0x3d044be6, 0x30476d3f, 0x34867088,
    0xec7dd0d2, 0xe8bccd65, 0xe5ffebbc, 0xe13ef60b, 0xff79a60e, 0xfbb8bbb9,
    0xf6fb9d60, 0xf23a80d7, 0xca753d6a, 0xceb420dd, 0xc3f70604, 0xc7361bb3,
    0xd9714bb6, 0xddb05601, 0xd0f370d8, 0xd4326d6f, 0xa06c0ba2, 0xa4ad1615,
    0xa9ee30cc, 0xad2f2d7b, 0xb3687d7e, 0xb7a960c9, 0xbaea4610, 0xbe2b5ba7,
    0x8664e61a, 0x82a5fbad, 0x8fe6dd74, 0x8b27c0c3, 0x956090c6, 0x91a18d71,
    0x9ce2aba8, 0x9823b61f, 0x745e6632, 0x709f7b85, 0x7ddc5d5c, 0x791d40eb,
    0x675a10ee, 0x639b0d59, 0x6ed82b80, 0x6a193637, 0x52568b8a, 0x5697963d,
    0x5bd4b0e4, 0x5f15ad53, 0x4152fd56, 0x4593e0e1, 0x48d0c638, 0x4c11db8f,
    0x384fbd42, 0x3c8ea0f5, 0x31cd862c, 0x350c9b9b, 0x2b4bcb9e, 0x2f8ad629,
    0x22c9f0f0, 0x2608ed47, 0x1e4750fa, 0x1a864d4d, 0x17c56b94, 0x13047623,
    0x0d432626, 0x09823b91, 0x04c11d48, 0x000000ff
};

uint32_t crc32cksum_byte(uint32_t crc, void const *mem, size_t len) {
    uint8_t const *data = mem;
    if (data == NULL)
        return 0xffffffff;
    for (size_t i = 0; i < len; i++)
        crc = (crc << 8) ^ table_byte[((crc >> 24) ^ data[i]) & 0xff];
    return crc;
}

初始 CRC 值（返回mem == NULL）为0xffffffff。

正如 @LarsChristianJensen 所指出的，您需要以小端顺序将消息的长度附加到消息中，以表示长度所需的字节数。（如果长度为零，则附加零字节。）CRC 是根据消息 + 附加长度计算的。

您可以使用生成上述代码，以及用于更快的 slice-by 8 实现的代码。（Stackoverflow 答案的长度有限，这使我无法将代码放入此答案中。）

cksum 程序还处理输入后的输入流长度的表示，因此我认为您需要传递“moin\x04”才能获得预期结果。 — 
我看到了C版本。但 Go 模块有一些特定于架构的优化。我想使用它们而不是使用一些新代码。我想知道是否可以制作一个与“hash/crc32”一起使用的自定义表。 — 
不，你没有阅读我的回答。 hash/crc32不可能通过修改代码或翻转输入字节中的位（这将抵消任何速度优势）来计算此 CRC，因为它向相反方向移动。 — 
如果您想要按 8 切片实现，请参阅我的答案的末尾。 — 
这与 OpenGroup 网站上的算法非常相似，并且具有相同的性能。 —

Answer 3

这是我的结论：

使用通用代码不可能超越 Go 标准实现的性能。
不可能cksum在保持 Go 标准实现的性能的同时准备输入以实现兼容性。

通用代码比 Go 的优化代码慢一个数量级以上：

goos: linux
goarch: amd64
cpu: Intel(R) Core(TM) i9-10900X CPU @ 3.70GHz
Benchmark_OpenGroup
Benchmark_OpenGroup-6                      16576         63555 ns/op
Benchmark_HashCrc32ReverseInput
Benchmark_HashCrc32ReverseInput-6          16914         73833 ns/op
Benchmark_HashCrc32ReverseTable
Benchmark_HashCrc32ReverseTable-6          16210         68378 ns/op
Benchmark_Crcany
Benchmark_Crcany-6                         18874         63727 ns/op
Benchmark_HashCRC32Native
Benchmark_HashCRC32Native-6               866377          1392 ns/op
PASS

最后的替代方案是：

缓慢并兼容cksum.
速度快且不兼容cksum。

测试程序：

package cksum

import (
    _ "embed"
    "encoding/binary"
    "fmt"
    "hash/crc32"
    "math/bits"
    "testing"
)

//======================================================================
// Input data

func append_length(bytes []byte) []byte {
    length := []byte{}
    n := len(bytes)
    for n != 0 {
        length = append(length, byte(n&0377))
        n >>= 8
    }
    return append(bytes, length...)
}

//go:generate bash -c "printf moin > moin"
//go:embed moin
var file_moin []byte

//go:generate bash -c "cksum moin > moin.cksum"
//go:embed moin.cksum
var cksum_moin string

//go:generate bash -c "if [ ! -e 40BD0 ]; then wget -q https://api.pwnedpasswords.com/range/40BD0; fi"
//go:embed 40BD0
var file_40BD0 []byte

//go:generate bash -c "cksum 40BD0 > 40BD0.cksum"
//go:embed 40BD0.cksum
var cksum_40BD0 string

var (
    data_short  []byte
    data_long   []byte
    cksum_short uint32
    cksum_long  uint32
)

func init() {
    data_short = append_length(file_moin)
    data_long = append_length(file_40BD0)

    var err error
    _, err = fmt.Sscanf(cksum_moin, "%d", &cksum_short)
    if err != nil {
        panic(err)
    }
    _, err = fmt.Sscanf(cksum_40BD0, "%d", &cksum_long)
    if err != nil {
        panic(err)
    }
}

//======================================================================
// Translation of the OpenGroup C reference implementation
//
// https://pubs.opengroup.org/onlinepubs/007904975/utilities/cksum.html

var opengroup_crctab = []uint32{
    0x00000000,
    0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
    0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6,
    0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
    0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac,
    0x5bd4b01b, 0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f,
    0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a,
    0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
    0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58,
    0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033,
    0xa4ad16ea, 0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe,
    0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
    0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4,
    0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
    0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5,
    0x2ac12072, 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
    0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07,
    0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c,
    0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1,
    0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
    0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b,
    0xbb60adfc, 0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698,
    0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d,
    0x94ea7b2a, 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
    0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f,
    0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
    0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80,
    0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
    0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a,
    0x58c1663d, 0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629,
    0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c,
    0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
    0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e,
    0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65,
    0xeba91bbc, 0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8,
    0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
    0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2,
    0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
    0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74,
    0x857130c3, 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
    0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21,
    0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a,
    0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087,
    0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
    0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d,
    0x2056cd3a, 0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce,
    0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb,
    0xdbee767c, 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
    0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09,
    0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
    0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf,
    0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4}

/*
unsigned long memcrc(const unsigned char *b, size_t n)
{
    // Input arguments:
    // const char*   b == byte sequence to checksum
    // size_t        n == length of sequence

    register unsigned   i, c, s = 0;

    for (i = n; i > 0; --i) {
        c = (unsigned)(*b++);
        s = (s << 8) ^ crctab[(s >> 24) ^ c];
    }

    // Extend with the length of the string.
    while (n != 0) {
        c = n & 0377;
        n >>= 8;
        s = (s << 8) ^ crctab[(s >> 24) ^ c];
    }

    return ˜s;
}
*/

func OpenGroup(bytes []byte) uint32 {
    var s uint32
    for _, c := range bytes {
        s = (s << 8) ^ opengroup_crctab[(s>>24)^uint32(c)]
    }
    return ^s
}

//======================================================================
// Implementation using hash/crc32 by reversing input

func HashCrc32ReverseInput(bytes []byte) uint32 {
    input := make([]byte, len(bytes))

    // because refin=false
    for i := range bytes {
        input[i] = bits.Reverse8(bytes[i])
    }

    // because init=0x00000000
    v := crc32.Update(^uint32(0), crc32.IEEETable, input)

    // because refout=false
    v = bits.Reverse32(v)

    return v
}

//======================================================================
// Implementation using hash/crc32 by reversing the table

func reverseEachByte(n uint32) uint32 {
    var buf [4]byte
    binary.BigEndian.PutUint32(buf[:], n)
    buf[0] = bits.Reverse8(buf[0])
    buf[1] = bits.Reverse8(buf[1])
    buf[2] = bits.Reverse8(buf[2])
    buf[3] = bits.Reverse8(buf[3])
    return binary.BigEndian.Uint32(buf[:])
}

var table crc32.Table

func init() {
    for i, v := range crc32.IEEETable {
        table[bits.Reverse8(uint8(i))] = reverseEachByte(v)
    }
}

func HashCrc32ReverseTable(bytes []byte) uint32 {
    v := crc32.Update(^uint32(0), &table, bytes)
    v = reverseEachByte(v)
    v = bits.Reverse32(v)
    return v
}

//======================================================================
// Translation of the Crcany C implementation

var table_byte = []uint32{
    0xb1f7404b, 0xb5365dfc, 0xb8757b25, 0xbcb46692, 0xa2f33697, 0xa6322b20,
    0xab710df9, 0xafb0104e, 0x97ffadf3, 0x933eb044, 0x9e7d969d, 0x9abc8b2a,
    0x84fbdb2f, 0x803ac698, 0x8d79e041, 0x89b8fdf6, 0xfde69b3b, 0xf927868c,
    0xf464a055, 0xf0a5bde2, 0xeee2ede7, 0xea23f050, 0xe760d689, 0xe3a1cb3e,
    0xdbee7683, 0xdf2f6b34, 0xd26c4ded, 0xd6ad505a, 0xc8ea005f, 0xcc2b1de8,
    0xc1683b31, 0xc5a92686, 0x29d4f6ab, 0x2d15eb1c, 0x2056cdc5, 0x2497d072,
    0x3ad08077, 0x3e119dc0, 0x3352bb19, 0x3793a6ae, 0x0fdc1b13, 0x0b1d06a4,
    0x065e207d, 0x029f3dca, 0x1cd86dcf, 0x18197078, 0x155a56a1, 0x119b4b16,
    0x65c52ddb, 0x6104306c, 0x6c4716b5, 0x68860b02, 0x76c15b07, 0x720046b0,
    0x7f436069, 0x7b827dde, 0x43cdc063, 0x470cddd4, 0x4a4ffb0d, 0x4e8ee6ba,
    0x50c9b6bf, 0x5408ab08, 0x594b8dd1, 0x5d8a9066, 0x8571303c, 0x81b02d8b,
    0x8cf30b52, 0x883216e5, 0x967546e0, 0x92b45b57, 0x9ff77d8e, 0x9b366039,
    0xa379dd84, 0xa7b8c033, 0xaafbe6ea, 0xae3afb5d, 0xb07dab58, 0xb4bcb6ef,
    0xb9ff9036, 0xbd3e8d81, 0xc960eb4c, 0xcda1f6fb, 0xc0e2d022, 0xc423cd95,
    0xda649d90, 0xdea58027, 0xd3e6a6fe, 0xd727bb49, 0xef6806f4, 0xeba91b43,
    0xe6ea3d9a, 0xe22b202d, 0xfc6c7028, 0xf8ad6d9f, 0xf5ee4b46, 0xf12f56f1,
    0x1d5286dc, 0x19939b6b, 0x14d0bdb2, 0x1011a005, 0x0e56f000, 0x0a97edb7,
    0x07d4cb6e, 0x0315d6d9, 0x3b5a6b64, 0x3f9b76d3, 0x32d8500a, 0x36194dbd,
    0x285e1db8, 0x2c9f000f, 0x21dc26d6, 0x251d3b61, 0x51435dac, 0x5582401b,
    0x58c166c2, 0x5c007b75, 0x42472b70, 0x468636c7, 0x4bc5101e, 0x4f040da9,
    0x774bb014, 0x738aada3, 0x7ec98b7a, 0x7a0896cd, 0x644fc6c8, 0x608edb7f,
    0x6dcdfda6, 0x690ce011, 0xd8fba0a5, 0xdc3abd12, 0xd1799bcb, 0xd5b8867c,
    0xcbffd679, 0xcf3ecbce, 0xc27ded17, 0xc6bcf0a0, 0xfef34d1d, 0xfa3250aa,
    0xf7717673, 0xf3b06bc4, 0xedf73bc1, 0xe9362676, 0xe47500af, 0xe0b41d18,
    0x94ea7bd5, 0x902b6662, 0x9d6840bb, 0x99a95d0c, 0x87ee0d09, 0x832f10be,
    0x8e6c3667, 0x8aad2bd0, 0xb2e2966d, 0xb6238bda, 0xbb60ad03, 0xbfa1b0b4,
    0xa1e6e0b1, 0xa527fd06, 0xa864dbdf, 0xaca5c668, 0x40d81645, 0x44190bf2,
    0x495a2d2b, 0x4d9b309c, 0x53dc6099, 0x571d7d2e, 0x5a5e5bf7, 0x5e9f4640,
    0x66d0fbfd, 0x6211e64a, 0x6f52c093, 0x6b93dd24, 0x75d48d21, 0x71159096,
    0x7c56b64f, 0x7897abf8, 0x0cc9cd35, 0x0808d082, 0x054bf65b, 0x018aebec,
    0x1fcdbbe9, 0x1b0ca65e, 0x164f8087, 0x128e9d30, 0x2ac1208d, 0x2e003d3a,
    0x23431be3, 0x27820654, 0x39c55651, 0x3d044be6, 0x30476d3f, 0x34867088,
    0xec7dd0d2, 0xe8bccd65, 0xe5ffebbc, 0xe13ef60b, 0xff79a60e, 0xfbb8bbb9,
    0xf6fb9d60, 0xf23a80d7, 0xca753d6a, 0xceb420dd, 0xc3f70604, 0xc7361bb3,
    0xd9714bb6, 0xddb05601, 0xd0f370d8, 0xd4326d6f, 0xa06c0ba2, 0xa4ad1615,
    0xa9ee30cc, 0xad2f2d7b, 0xb3687d7e, 0xb7a960c9, 0xbaea4610, 0xbe2b5ba7,
    0x8664e61a, 0x82a5fbad, 0x8fe6dd74, 0x8b27c0c3, 0x956090c6, 0x91a18d71,
    0x9ce2aba8, 0x9823b61f, 0x745e6632, 0x709f7b85, 0x7ddc5d5c, 0x791d40eb,
    0x675a10ee, 0x639b0d59, 0x6ed82b80, 0x6a193637, 0x52568b8a, 0x5697963d,
    0x5bd4b0e4, 0x5f15ad53, 0x4152fd56, 0x4593e0e1, 0x48d0c638, 0x4c11db8f,
    0x384fbd42, 0x3c8ea0f5, 0x31cd862c, 0x350c9b9b, 0x2b4bcb9e, 0x2f8ad629,
    0x22c9f0f0, 0x2608ed47, 0x1e4750fa, 0x1a864d4d, 0x17c56b94, 0x13047623,
    0x0d432626, 0x09823b91, 0x04c11d48, 0x000000ff}

/*
uint32_t crc32cksum_byte(uint32_t crc, void const *mem, size_t len) {
    uint8_t const *data = mem;
    if (data == NULL)
        return 0xffffffff;
    for (size_t i = 0; i < len; i++)
        crc = (crc << 8) ^ table_byte[((crc >> 24) ^ data[i]) & 0xff];
    return crc;
}
*/

func Crcany(data []byte) uint32 {
    crc := uint32(0xffffffff)
    for i := 0; i < len(data); i++ {
        crc = (crc << 8) ^ table_byte[((crc>>24)^uint32(data[i]))&0xff]
    }
    return crc
}

//======================================================================
// Tests with short input

func Test_OpenGroup_Short(t *testing.T) {
    setpoint := cksum_short
    reading := OpenGroup(data_short)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

func Test_HashCrc32ReverseInput_Short(t *testing.T) {
    setpoint := cksum_short
    reading := HashCrc32ReverseInput(data_short)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

func Test_HashCrc32ReverseTable_Short(t *testing.T) {
    setpoint := cksum_short
    reading := HashCrc32ReverseTable(data_short)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

func Test_Crcany_Short(t *testing.T) {
    setpoint := cksum_short
    reading := Crcany(data_short)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

//======================================================================
// Tests with long input

func Test_Opengroup_Long(t *testing.T) {
    setpoint := cksum_long
    reading := OpenGroup(data_long)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

func Test_HashCrc32ReverseInput_Long(t *testing.T) {
    setpoint := cksum_long
    reading := HashCrc32ReverseInput(data_long)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

func Test_HashCrc32ReverseTable_Long(t *testing.T) {
    setpoint := cksum_long
    reading := HashCrc32ReverseTable(data_long)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

func Test_Crcany_Long(t *testing.T) {
    setpoint := cksum_long
    reading := Crcany(data_long)
    if reading != setpoint {
        t.Fatalf(`Wrong cksum: setpoint=%v reading=%v`, setpoint, reading)
    }
}

//======================================================================
// Benchmarks

func Benchmark_OpenGroup(b *testing.B) {
    for n := 0; n < b.N; n++ {
        _ = OpenGroup(data_long)
    }
}

func Benchmark_HashCrc32ReverseInput(b *testing.B) {
    for n := 0; n < b.N; n++ {
        _ = HashCrc32ReverseInput(data_long)
    }
}

func Benchmark_HashCrc32ReverseTable(b *testing.B) {
    for n := 0; n < b.N; n++ {
        _ = HashCrc32ReverseTable(data_long)
    }
}

func Benchmark_Crcany(b *testing.B) {
    for n := 0; n < b.N; n++ {
        _ = Crcany(data_long)
    }
}

func Benchmark_HashCRC32Native(b *testing.B) {
    for n := 0; n < b.N; n++ {
        _ = crc32.ChecksumIEEE(data_long)
    }
}

// Local Variables:
// compile-command: "go test -v -bench=. cksum_test.go"
// End:

go – 如何获得与 cksum 相同的 CRC32？

3 个回答
3

3 个回答 3

3 个回答
3