跨平台应用的CRC [英] CRC for cross platform applications

问题描述

我希望在VB.NET或C＃应用程序以及C / Linux应用程序中使用通用的CRC逻辑。我有一个C / Linux应用程序，它可以与Web服务（用C＃编写）交互，也可以与Web应用程序（用VB.NET编写）交互。对于某些数据，我想从.NET端向数据本身（例如文件）添加CRC，并在客户端上检查数据的完整性（检查CRC），反之亦然。

I wish to use common CRC logic in a VB.NET or C# application as well as on a C/Linux application. I have one C/Linux application that interacts with a webservice (written in C#) and also a web application (written in VB.NET). For some data, I want to add a CRC to the data itself (say a file) from the .NET side and check for the integrity of the data (checking the CRC) on the client - and also vice-versa.

有人可以引导我吗？

推荐答案

由于CRC实施是一个班轮，我认为您对此没有任何问题。维基百科提供了几种不同语言的CRC源代码的链接。您真正需要关心的唯一问题是将CRC实际存储在文件中时的字节序。

Since CRC implementation is a one-liner, I don't think you've have any problem with that. wikipedia has links to CRC source code in several different languages. The only thing you need to care about for portability is the endian-ness when you actually store the CRC in the file.

编辑：确实，单线复制代码不会有问题。

Really, with a one-liner duplicating code is not going to be a problem.

C或C ++版本

const uint16_t table[256] = {
 0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
 0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
 0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
 0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
 0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
 0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
 0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
 0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
 0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
 0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
 0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
 0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
 0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
 0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
 0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
 0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
 0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
 0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
 0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
 0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
 0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
 0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
 0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
 0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
 0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
 0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
 0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
 0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
 0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
 0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
 0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
 0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78
};

void crc_update(uint8_t by, uint16_t& crc)
{
    crc = table[by ^ (uint8_t)(crc >> (16 - 8))] ^ (crc << 8);
}

C＃版本

readonly UInt16[] table = new UInt16[256] { 0x0000, 0x1189, ... };
void crc_update(Byte by, ref UInt16 crc)
{
    crc = (UInt16)(table[by ^ (crc >> (16 - 8))] ^ (crc << 8));
}

VB.NET版本

ReadOnly table As UInt16() = { &H0000, &H1189, ... }
Sub crc_update(ByVal by As System.Byte, ByRef crc As UInt16)
    crc = table(by Xor (crc >> (16 - 8))) Xor (crc << 8)
End Sub

要使用CCITT以外的16位CRC，请替换查找表。对于32位CRC，将所有出现的16替换为32，然后替换查找表。

To use a 16-bit CRC other than the CCITT, replace the lookup table. For a 32-bit CRC, replace all occurances of 16 with 32 and replace the lookup table.

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