CRC校驗代碼與使用技巧

CRC校驗代碼與使用技巧<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

作者：彭學周（Favory.Peng）

       在工業控制和通訊中，爲了保證數據通訊的可靠性，我們會需要在通訊數據報文中加入校驗碼，以確保發送和接收到的數據的一致，保證數據的完整；

       對於校驗碼的生成方法，各家公司都會有自己的一套，但最常用的莫過於CRC校驗啦，關於CRC校驗的介紹我這裏就不多提啦，網上一搜就可以看到很多很多關於CRC校驗的文章，感興趣的朋友可以自己去搜索一下；

在這裏，我主要想給大家分享一下CRC校驗和計算代碼，非常簡單實用，你無需瞭解繁雜的CRC原理，可以直接使用這段代碼解決你的工程中的應用需求，希望對大家有所幫助；

頭文件crc_pro.h

1. #ifndef Ucrc_proH
2. #define Ucrc_proH
4. typedef unsigned char byte;
5. typedef unsigned short int uint;
7. byte __fastcall crc_8(byte buf[],int off ,int len);
8. uint __fastcall crc_16(byte *buf,int len);
10. #endif

程序文件crc_pro.cpp

1. #include "crc_pro.h"
3. //16位CRC校驗表
4. uint CRC16_Table[]=
5. {
6.     0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
7.     0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
8.     0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
9.     0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
10.     0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
11.     0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
12.     0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
13.     0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
14.     0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
15.     0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
16.     0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
17.     0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
18.     0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
19.     0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
20.     0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
21.     0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
22.     0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
23.     0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
24.     0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
25.     0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
26.     0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
27.     0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
28.     0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
29.     0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
30.     0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
31.     0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
32.     0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
33.     0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
34.     0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
35.     0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
36.     0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
37.     0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
38. };
40. //8位CRC校驗表
41. byte CRC8_Table[]=
42. {
43.    0,94,188,226,97,63,221,131,194,156,126,32,163,253,31,65,
44.    157,195,33,127,252,162,64,30, 95,1,227,189,62,96,130,220,
45.    35,125,159,193,66,28,254,160,225,191,93,3,128,222,60,98,
46.    190,224,2,92,223,129,99,61,124,34,192,158,29,67,161,255,
47.    70,24,250,164,39,121,155,197,132,218,56,102,229,187,89,7,
48.    219,133,103,57,186,228,6,88,25,71,165,251,120,38,196,154,
49.    101,59,217,135,4,90,184,230,167,249,27,69,198,152,122,36,
50.    248,166,68,26,153,199,37,123,58,100,134,216,91,5,231,185,
51.    140,210,48,110,237,179,81,15,78,16,242,172,47,113,147,205,
52.    17,79,173,243,112,46,204,146,211,141,111,49,178,236,14,80,
53.    175,241,19,77,206,144,114,44,109,51,209,143,12,82,176,238,
54.    50,108,142,208,83,13,239,177,240,174,76,18,145,207,45,115,
55.    202,148,118,40,171,245,23,73,8,86,180,234,105,55,213,139,
56.    87,9,235,181,54,104,138,212,149,203, 41,119,244,170,72,22,
57.    233,183,85,11,136,214,52,106,43,117,151,201,74,20,246,168,
58.    116,42,200,150,21,75,169,247,182,232,10,84,215,137,107,53
59. };
61. //8位CRC校驗計算函數
62. byte __fastcall crc_8(byte buf[],int off,int len)
63. {
64.    byte crc;
65.    crc=0;
66.    for (int i = off; i < len ; i ++)
67.    {
68.      crc = CRC8_Table[crc ^ buf[i]];
69.    }
70.    return crc;
71. }
73. //16位CRC校驗計算函數
74. uint __fastcall crc_16(byte *buf,int len)
75. {
76.     uint crc=0xffff;
77.     while(len>0)
78.     {
79.     crc=(crc>>8)^CRC16_Table[(crc^*buf)&0xff];
80.     len--;
81.         buf++;
82.     }
83.     return ~crc;
84. }

使用說明：

在串口通訊中，數據報文都是按字節的發送，我們將需要發送的報文數據存放到Sendbuf中，定義爲：byte Sendbuf[32]；

我們假定通訊報文的格式爲：

第0位爲報文頭，中間12位爲報文內容，13位/13、14位存放CRC校驗（8/16位CRC校驗），第14/15位爲報文尾；

 

1、如果需要計算8位CRC校驗，報文頭不參加運算，則代碼爲：

Sendbuf[13]= crc_8(Sendbuf,1,12);

 

2、如果需要計算16位CRC校驗，報文頭不參加運算，則代碼爲：

Uint crc16= crc_16(&Sendbuf[1],12);

Sendbuf[13]=crc16;

Sendbuf[14]=crc16 >>8;