CRC16-ITU证明

Question

人。我使用CRC16-ITU检查来比较一些数据，但是当我将CRC16-ITU和分组数据与来自设备的CRC16进行比较时，它不匹配。

这是CRC16-ITU表。

  

u16 crctab16 [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};

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我使用这段代码来制作crc

u16 fcs16(u16 fcs, unsigned char *cp, int len)
{
    while(len--)
        fcs = (fcs >> 8) ^ crctab16[(fcs ^ *cp++) & 0xff];

    return(fcs);
}

以下是来自设备

的数据包数据的示例

7e 01 11 97 17 7e

97 17表示CRC16为小端方法。

当我在我的项目中使用CRC16-ITU代码时，我得到了这个“4edf”

我完全不明白为什么这些数据之间存在不匹配。

如果您有任何想法，请为我​​发表评论

THX

Answer 1

您的CRC 0x4edf对应于CRC-16 / X-25算法（使用 来自http://reveng.sourceforge.net/crc-catalogue/的符号） 在字节序列7e 01 11上。如果您计算的CRC超过01 11 应该将0x1797作为16位值（或97 17作为两个字节）。