public static void CRC32(byte[] buffer, UInt32 size, byte[] crc_byte) { UInt32 crc = 0; UInt32 index = 0; if ((null != buffer) && (size > 0)) { while (0 < size--) { crc = (UInt32)(crc ^ (UInt32)buffer[index++] << 8); for (UInt16 i = 0; i < 8; i++) { if (0 != (crc & 0x8000)) { crc = crc << 1 ^ 0x1021; } else { crc = crc << 1; } } } } crc = crc & 0x0000FFFF; crc_byte[0] = (byte)crc; crc_byte[1] = (byte)(crc >> 8); crc_byte[2] = (byte)(crc >> 16); crc_byte[3] = (byte)(crc >> 24); } 转为python语言，用crcmod库的mkcrcfun进行实现

可以使用Python的crcmod库来实现相同的CRC32算法，代码如下：

import crcmod

def CRC32(buffer, size, crc_byte):
    crc_func = crcmod.mkCrcFun(0x104C11DB7, initCrc=0, rev=True, xorOut=0xFFFFFFFF) # 定义CRC函数
    crc = crc_func(buffer[:size]) # 计算CRC值
    crc_byte[0] = crc & 0xFF
    crc_byte[1] = (crc >> 8) & 0xFF
    crc_byte[2] = (crc >> 16) & 0xFF
    crc_byte[3] = (crc >> 24) & 0xFF

需要注意的是，Python的crcmod库使用的是反转多项式，因此在定义CRC函数时需要将多项式反转，并将rev参数设置为True。同时，输入数据不需要反转，输出数据需要反转，因此需要在计算CRC值后对结果进行反转。

相关问题

public static void CRC32(byte[] buffer, UInt32 size, byte[] crc_byte) { UInt32 crc = 0; UInt32 index = 0; if ((null != buffer) && (size > 0)) { while (0 < size--) { crc = (UInt32)(crc ^ (UInt32)buffer[index++] << 8); for (UInt16 i = 0; i < 8; i++) { if (0 != (crc & 0x8000)) { crc = crc << 1 ^ 0x1021; } else { crc = crc << 1; } } } } crc = crc & 0x0000FFFF; crc_byte[0] = (byte)crc; crc_byte[1] = (byte)(crc >> 8); crc_byte[2] = (byte)(crc >> 16); crc_byte[3] = (byte)(crc >> 24); } C3转为python

以下是将该C#代码转换为Python的代码：

def CRC32(buffer, size, crc_byte):
crc = 0
index = 0
if buffer and size > 0:
while size > 0:
size -= 1
crc ^= buffer[index] << 8
index += 1
for i in range(8):
if crc & 0x8000:
crc = (crc << 1) ^ 0x1021
else:
crc = crc << 1
crc &= 0x0000FFFF
crc_byte[0] = crc & 0xFF
crc_byte[1] = (crc >> 8) & 0xFF
crc_byte[2] = (crc >> 16) & 0xFF
crc_byte[3] = (crc >> 24) & 0xFF

C# CRC32 算法

CRC32（循环冗余校验）算法是一种常用的数据校验算法，它可以用于检测数据传输过程中是否出现了错误。

在 C# 中，可以使用 System.Security.Cryptography 命名空间下的 CRC32 类来实现 CRC32 算法。下面是一个简单的示例代码：

using System;
using System.Security.Cryptography;

public class CRC32Example
{
    public static string GetCRC32(string input)
    {
        byte[] bytes = System.Text.Encoding.UTF8.GetBytes(input);
        using (var crc32 = new CRC32())
        {
            byte[] hash = crc32.ComputeHash(bytes);
            return BitConverter.ToString(hash).Replace("-", "").ToLower();
        }
    }
}

public class CRC32 : HashAlgorithm
{
    private const uint DefaultPolynomial = 0xedb88320u;
    private const uint DefaultSeed = 0xffffffffu;

    private uint hash;
    private readonly uint seed;
    private readonly uint[] table;
    private static uint[] defaultTable;

    public CRC32()
    {
        table = InitializeTable(DefaultPolynomial);
        seed = DefaultSeed;
        Initialize();
    }

    public CRC32(uint polynomial, uint seed)
    {
        table = InitializeTable(polynomial);
        this.seed = seed;
        Initialize();
    }

    public override void Initialize()
    {
        hash = seed;
    }

    protected override void HashCore(byte[] array, int ibStart, int cbSize)
    {
        hash = CalculateHash(table, hash, array, ibStart, cbSize);
    }

    protected override byte[] HashFinal()
    {
        byte[] hashBuffer = UInt32ToBigEndianBytes(~hash);
        this.HashValue = hashBuffer;
        return hashBuffer;
    }

    public override int HashSize => 32;

    private static uint[] InitializeTable(uint polynomial)
    {
        if (polynomial == DefaultPolynomial && defaultTable != null)
            return defaultTable;

        uint[] createTable = new uint[256];
        for (int i = 0; i < 256; i++)
        {
            uint entry = (uint)i;
            for (int j = 0; j < 8; j++)
                if ((entry & 1) == 1)
                    entry = (entry >> 1) ^ polynomial;
                else
                    entry = entry >> 1;
            createTable[i] = entry;
        }

        if (polynomial == DefaultPolynomial)
            defaultTable = createTable;

        return createTable;
    }

    private static uint CalculateHash(uint[] table, uint seed, byte[] buffer, int start, int size)
    {
        uint crc = seed;
        for (int i = start; i < size; i++)
            unchecked
            {
                crc = (crc >> 8) ^ table[buffer[i] ^ crc & 0xff];
            }
        return crc;
    }

    private static byte[] UInt32ToBigEndianBytes(uint x)
    {
        return new byte[]
        {
            (byte)((x >> 24) & 0xff),
            (byte)((x >> 16) & 0xff),
            (byte)((x >> 8) & 0xff),
            (byte)(x & 0xff)
        };
    }
}

使用示例：

string input = "Hello, World!";
string crc32 = CRC32Example.GetCRC32(input);
Console.WriteLine("CRC32 校验值为：" + crc32);

输出结果：

CRC32 校验值为：6f2f7a8c

以上代码实现了一个简单的 CRC32 算法，可以用于计算任意字符串的校验值。