CRC16校驗算法實現(xiàn)

CRC16校驗算法實現(xiàn)（轉(zhuǎn)）（2011—07—2717:28:14）轉(zhuǎn)載▼標(biāo)簽：分類：電子專業(yè)雜談循環(huán)冗余碼校驗英文名稱為CyclicalRedundancyCheck,簡稱CRC。它是利用除法及余數(shù)的原理來作錯誤偵測（ErrorDetecting）的。實際應(yīng)用時，發(fā)送裝置計算出CRC值并隨數(shù)據(jù)一同發(fā)送給接收裝置，接收裝置對收到的數(shù)據(jù)重新計算CRC并與收到的CRC相比較，若兩個CRC值不同，則說明數(shù)據(jù)通訊出現(xiàn)錯誤。根據(jù)應(yīng)用環(huán)境與習(xí)慣的不同，CRC又可分為以下幾種標(biāo)準(zhǔn)：CRC-12碼；CRC-16碼；CRC-CCITT碼；CRC-32碼。CRC-12碼通常用來傳送6-bit字符串。CRC-16及CRC-CCITT碼則用是來傳送8-bit字符，其中CRC-16為美國采用，而CRC-CCITT為歐洲國家所采用。CRC-32碼大都被采用在一種稱為Point-to-Point的同步傳輸中。下面著重是CRC-16檢驗碼的生成過程。CRC-16碼由兩個字節(jié)構(gòu)成，在開始時CRC寄存器的每一位都預(yù)置為1,然后把CRC寄存器與8-bit的數(shù)據(jù)進(jìn)行異或，之后對CRC寄存器從高到低進(jìn)行移位，在最高位（MSB）的位置補(bǔ)零，而最低位（LSB，移位后已經(jīng)被移出CRC寄存器）如果為1,則把寄存器與預(yù)定義的多項式碼進(jìn)行異或，否則如果LSB為零，則無需進(jìn)行異或。重復(fù)上述的由高至低的移位8次，第一個8-bit數(shù)據(jù)處理完畢，用此時CRC寄存器的值與下一個8-bit數(shù)據(jù)異或并進(jìn)行如前一個數(shù)據(jù)似的8次移位。所有的字符處理完成后CRC寄存器內(nèi)的值即為最終的CRC值。下面為CRC16的計算過程，其中生成多項式為:X16+X15+X2+1：設(shè)置CRC寄存器，并給其賦值FFFF(hex)。將數(shù)據(jù)的第一個8-bit字符與16位CRC寄存器的低8位進(jìn)行異或，并把結(jié)果存入CRC寄存器。CRC寄存器向右移一位，MSB補(bǔ)零，移出并檢查LSB。如果LSB為0重復(fù)第三步；若LSB為1，CRC寄存器與生成多項式碼相異或。重復(fù)第3與第4步直到8次移位全部完成。此時一個8-bit數(shù)據(jù)處理完畢。重復(fù)第2至第5步直到所有數(shù)據(jù)全部處理完成。最終CRC寄存器的內(nèi)容即為CRC值。校驗碼實現(xiàn)編寫CRC校驗程序有兩種辦法：一種為計算法，一種為查表法。下面是查表法的C語言實現(xiàn)：校驗碼算法程序?qū)崿F(xiàn)樣例(C語言)：//Test.cpp:Definestheentrypointfortheconsoleapplication.#include"stdafx.h"staticunsignedcharauchCRCHi[]={0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40};staticunsignedcharauchCRCLo[]={0x00,0xC0,0xC1,0x01,0xC3,0x03,0x02,0xC2,0xC6,0x06,0x07,0xC7,0x05,0xC5,0xC4,0x04,0xCC,0x0C,0x0D,0xCD,0x0F,0xCF,0xCE,0x0E,0x0A,0xCA,0xCB,0x0B,0xC9,0x09,0x08,0xC8,0xD8,0x18,0x19,0xD9,0x1B,0xDB,0xDA,0x1A,0x1E,0xDE,0xDF,0x1F,0xDD,0x1D,0x1C,0xDC,0x14,0xD4,0xD5,0x15,0xD7,0x17,0x16,0xD6,0xD2,0x12,0x13,0xD3,0x11,0xD1,0xD0,0x10,0xF0,0x30,0x31,0xF1,0x33,0xF3,0xF2,0x32,0x36,0xF6,0xF7,0x37,0xF5,0x35,0x34,0xF4,0x3C,0xFC,0xFD,0x3D,0xFF,0x3F,0x3E,0xFE,0xFA,0x3A,0x3B,0xFB,0x39,0xF9,0xF8,0x38,0x28,0xE8,0xE9,0x29,0xEB,0x2B,0x2A,0xEA,0xEE,0x2E,0x2F,0xEF,0x2D,0xED,0xEC,0x2C,0xE4,0x24,0x25,0xE5,0x27,0xE7,0xE6,0x26,0x22,0xE2,0xE3,0x23,0xE1,0x21,0x20,0xE0,0xA0,0x60,0x61,0xA1,0x63,0xA3,0xA2,0x62,0x66,0xA6,0xA7,0x67,0xA5,0x65,0x64,0xA4,0x6C,0xAC,0xAD,0x6D,0xAF,0x6F,0x6E,0xAE,0xAA,0x6A,0x6B,0xAB,0x69,0xA9,0xA8,0x68,0x78,0xB8,0xB9,0x79,0xBB,0x7B,0x7A,0xBA,0xBE,0x7E,0x7F,0xBF,0x7D,0xBD,0xBC,0x7C,0xB4,0x74,0x75,0xB5,0x77,0xB7,0xB6,0x76,0x72,0xB2,0xB3,0x73,0xB1,0x71,0x70,0xB0,0x50,0x90,0x91,0x51,0x93,0x53,0x52,0x92,0x96,0x56,0x57,0x97,0x55,0x95,0x94,0x54,0x9C,0x5C,0x5D,0x9D,0x5F,0x9F,0x9E,0x5E,0x5A,0x9A,0x9B,0x5B,0x99,0x59,0x58,0x98,0x88,0x48,0x49,0x89,0x4B,0x8B,0x8A,0x4A,0x4E,0x8E,0x8F,0x4F,0x8D,0x4D,0x4C,0x8C,0x44,0x84,0x85,0x45,0x87,0x47,0x46,0x86,0x82,0x42,0x43,0x83,0x41,0x81,0x80,0x40};unsignedshortCRC16(unsignedchar*puchMsg,unsignedshortusDataLen){unsignedcharuchCRCHi=0xFF;unsignedcharuchCRCLo=0xFF;unsignedcharuIndex;while(usDataLen--){ulndex=uchCRCHi人*puchMsg++;uchCRCHi=uchCRCLo人auchCRCHi[uIndex];uchCRCLo=auchCRCLo[uIndex];}return(uchCRCHi<<8|uchCRCLo);};voidmain(intargc,char*argv[]){unsignedcharsrc[21]={'1','2','3','6','3','4','2','3','4','2','9','8','7','3','6','5','2','8','9','3','5'};unsignedshortcode=CRC16(src,21);printf("theresultis%d/n",code);}以下是Delphi實現(xiàn)的代碼unitCRC16;interfaceusesWindows,SysUtils;functionCRC(a_strPuchMsg:string):LongWord;implementationconstct_ArrayCRCHi:array[0..255]ofLongWord=($00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,$00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40);ct_ArrayCRCLo:array[0..255]ofLongWord=($00,$C0,$C1,$01,$C3,$03,$02,$C2,$C6,$06,$07,$C7,$05,$C5,$C4,$04,$CC,$0C,$0D,$CD,$0F,$CF,$CE,$0E,$0A,$CA,$CB,$0B,$C9,$09,$08,$C8,$D8,$18,$19,$D9,$1B,$DB,$DA,$1A,$1E,$DE,$DF,$1F,$DD,$1D,$1C,$DC,$14,$D4,$D5,$15,$D7,$17,$16,$D6,$D2,$12,$13,$D3,$11,$D1,$D0,$10,$F0,$30,$31,$F1,$33,$F3,$F2,$32,$36,$F6,$F7,$37,$F5,$35,$34,$F4,$3C,$FC,$FD,$3D,$FF,$3F,$3E,$FE,$FA,$3A,$3B,$FB,$39,$F9,$F8,$38,$28,$E8,$E9,$29,$EB,$2B,$2A,$EA,$EE,$2E,$2F,$EF,$2D,$ED,$EC,$2C,$E4,$24,$25,$E5,$27,$E7,$E6,$26,$22,$E2,$E3,$23,$E1,$21,$20,$E0,$A0,$60,$61,$A1,$63,$A3,$A2,$62,$66,$A6,$A7,$67,$A5,$65,$64,$A4,$6C,$AC,$AD,$6D,$AF,$6F,$6E,$AE,$AA,$6A,$6B,$AB,$69,$A9,$A8,$68,$78,$B8,$B9,$79,$BB,$7B,$7A,$BA,$BE,$7E,$7F,$BF,$7D,$BD,$BC,$7C,$B4,$74,$