CRC 源码大全

       循环冗余校验码（Cylclic Redundancy Check Code),简称CRC码。常用的CRC数有8，16，32，CRC位数越大，数据越不易受干扰，但运算时间加长。一般关于通信的书籍都有介绍。简单原理是将要传输的数据视为一堆连续位组成的一整个数值，并将此数值除一个特定的除数，通常以二进制表示，此除数称为衍生多项式（Generation Polynomial).
      一般数据量不大时，使用Checksume验错方式就行了；数据量大时，就用CRC了；据理论统计，用CRC16时，超过17个连续位的错误侦测率为99。9969，小于此的为100。

1、CRC-12 的生成多项式为：P(x)=X^12 X^11 X^3 X^2 1

#include <stdio.h>
#include "crc16.h"

static code unsigned int Crc16Table[256] =
{
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
};

unsigned int UpdateCrc16(unsigned char Octet,unsigned int CRC)
{
return Crc16Table[ (CRC >> 8) & 255] ^ (CRC << 8) ^ Octet;
}

unsigned int UpdateCRC(unsigned char Octet,unsigned int CRC)
{
return (CRC << 8) ^ Crc16Table[ (CRC >> 8) ^ Octet ];
}

MOV A,RCRC1H
XRL A,RCRC2L
CPL A
MOV RCRC1H,A

MOV A,RCRC1L
CPL A
MOV RCRC1L,A

MOV R6,RCRC1H
MOV R7,RCRC1L

RET
;-------------------------------------------
CRCTAB1:
DB 000H,089H,012H,09BH,024H,0ADH,036H,0BFH
DB 048H,0C1H,05AH,0D3H,06CH,0E5H,07EH,0F7H
DB 081H,008H,093H,01AH,0A5H,02CH,0B7H,03EH
DB 0C9H,040H,0DBH,052H,0EDH,064H,0FFH,076H
DB 002H,08BH,010H,099H,026H,0AFH,034H,0BDH
DB 04AH,0C3H,058H,0D1H,06EH,0E7H,07CH,0F5H
DB 083H,00AH,091H,018H,0A7H,02EH,0B5H,03CH
DB 0CBH,042H,0D9H,050H,0EFH,066H,0FDH,074H
DB 004H,08DH,016H,09FH,020H,0A9H,032H,0BBH
DB 04CH,0C5H,05EH,0D7H,068H,0E1H,07AH,0F3H
DB 085H,00CH,097H,01EH,0A1H,028H,0B3H,03AH
DB 0CDH,044H,0DFH,056H,0E9H,060H,0FBH,072H
DB 006H,08FH,014H,09DH,022H,0ABH,030H,0B9H
DB 04EH,0C7H,05CH,0D5H,06AH,0E3H,078H,0F1H
DB 087H,00EH,095H,01CH,0A3H,02AH,0B1H,038H
DB 0CFH,046H,0DDH,054H,0EBH,062H,0F9H,070H
DB 008H,081H,01AH,093H,02CH,0A5H,03EH,0B7H
DB 040H,0C9H,052H,0DBH,064H,0EDH,076H,0FFH
DB 089H,000H,09BH,012H,0ADH,024H,0BFH,036H
DB 0C1H,048H,0D3H,05AH,0E5H,06CH,0F7H,07EH
DB 00AH,083H,018H,091H,02EH,0A7H,03CH,0B5H
DB 042H,0CBH,050H,0D9H,066H,0EFH,074H,0FDH
DB 08BH,002H,099H,010H,0AFH,026H,0BDH,034H
DB 0C3H,04AH,0D1H,058H,0E7H,06EH,0F5H,07CH
DB 00CH,085H,01EH,097H,028H,0A1H,03AH,0B3H
DB 044H,0CDH,056H,0DFH,060H,0E9H,072H,0FBH
DB 08DH,004H,09FH,016H,0A9H,020H,0BBH,032H
DB 0C5H,04CH,0D7H,05EH,0E1H,068H,0F3H,07AH
DB 00EH,087H,01CH,095H,02AH,0A3H,038H,0B1H
DB 046H,0CFH,054H,0DDH,062H,0EBH,070H,0F9H
DB 08FH,006H,09DH,014H,0ABH,022H,0B9H,030H
DB 0C7H,04EH,0D5H,05CH,0E3H,06AH,0F1H,078H

CRCTAB2:
DB 000H,011H,023H,032H,046H,057H,065H,074H
DB 08CH,09DH,0AFH,0BEH,0CAH,0DBH,0E9H,0F8H
DB 010H,001H,033H,022H,056H,047H,075H,064H
DB 09CH,08DH,0BFH,0AEH,0DAH,0CBH,0F9H,0E8H
DB 021H,030H,002H,013H,067H,076H,044H,055H
DB 0ADH,0BCH,08EH,09FH,0EBH,0FAH,0C8H,0D9H
DB 031H,020H,012H,003H,077H,066H,054H,045H
DB 0BDH,0ACH,09EH,08FH,0FBH,0EAH,0D8H,0C9H
DB 042H,053H,061H,070H,004H,015H,027H,036H
DB 0CEH,0DFH,0EDH,0FCH,088H,099H,0ABH,0BAH
DB 052H,043H,071H,060H,014H,005H,037H,026H
DB 0DEH,0CFH,0FDH,0ECH,098H,089H,0BBH,0AAH
DB 063H,072H,040H,051H,025H,034H,006H,017H
DB 0EFH,0FEH,0CCH,0DDH,0A9H,0B8H,08AH,09BH
DB 073H,062H,050H,041H,035H,024H,016H,007H
DB 0FFH,0EEH,0DCH,0CDH,0B9H,0A8H,09AH,08BH
DB 084H,095H,0A7H,0B6H,0C2H,0D3H,0E1H,0F0H
DB 008H,019H,02BH,03AH,04EH,05FH,06DH,07CH
DB 094H,085H,0B7H,0A6H,0D2H,0C3H,0F1H,0E0H
DB 018H,009H,03BH,02AH,05EH,04FH,07DH,06CH
DB 0A5H,0B4H,086H,097H,0E3H,0F2H,0C0H,0D1H
DB 029H,038H,00AH,01BH,06FH,07EH,04CH,05DH
DB 0B5H,0A4H,096H,087H,0F3H,0E2H,0D0H,0C1H
DB 039H,028H,01AH,00BH,07FH,06EH,05CH,04DH
DB 0C6H,0D7H,0E5H,0F4H,080H,091H,0A3H,0B2H
DB 04AH,05BH,069H,078H,00CH,01DH,02FH,03EH
DB 0D6H,0C7H,0F5H,0E4H,090H,081H,0B3H,0A2H
DB 05AH,04BH,079H,068H,01CH,00DH,03FH,02EH
DB 0E7H,0F6H,0C4H,0D5H,0A1H,0B0H,082H,093H
DB 06BH,07AH,048H,059H,02DH,03CH,00EH,01FH
DB 0F7H,0E6H,0D4H,0C5H,0B1H,0A0H,092H,083H
DB 07BH,06AH,058H,049H,03DH,02CH,01EH,00FH

end

CRCCRT1:
MOV R7,#08H
MOV B,#00H
CRT1LOP1: CLR C
PUSH ACC
MOV A,B
RLC A
MOV B,A
POP ACC
RLC A
JNC CRT1LOP2
PUSH ACC
MOV A,B
XRL A,#CRCGENL
MOV B,A
POP ACC
XRL A,#CRCGENH
CRT1LOP2: DJNZ R7,CRT1LOP1
RET

RECEIVE:
SETB F0
LCALL CREATCRC
MOV A,CCRC1
XRL A,@R0
JNZ ERRORCRC
INC R0
MOV A,CCRC2
XRL A,@R0
JNZ ERRORCRC
LJMP EEND
ERRORCRC: CLR F0
EEND: RET

2) 所谓CRC码, 就是把数据块左移16位, 然后除以0x11021所得到的余数(由CCITT推荐).

3) 据此写出以下的CRC的C程序. *ptr指向发送数据块的首地址, len是数据块以字节为单位的长度.

uint cal_crc(uchar *ptr, uchar len) {
uint crc;
uchar i;

crc=0;
while(len--!=0) {
for(i=0x80; i!=0; i/=2) {
if((crc&0x8000)!=0) {crc*=2; crc^=0x1021;}
else crc*=2;
if((*ptr&i)!=0) crc^=0x1021;
}
ptr ;
}
return(crc);
}

unsigned char nLRC(unsigned char *str,unsigned int len)
{
unsigned int tmp;

for(tmp=0;tmp<len;tmp )
str[tmp]=str[tmp]-0x30;
return(LRC(str,len));
}

unsigned char LRC(unsigned char *uchMsg, unsigned int usDataLen)
{
unsigned char uchLRC = 0 ; /* LRC char initialized */

while (usDataLen--) /* pass through message */
uchLRC =*uchMsg ; /* buffer add buffer byte*/
/* without carry */

return((unsigned char)(-(char)(uchLRC)));
/* return twos complemen */
}

unsigned int nCRC16(unsigned char *puchMsg, unsigned int usDataLen)
{
unsigned char uchCRCHi = 0xFF ; /* high CRC unsigned char initialized */
unsigned char uchCRCLo = 0xFF ; /* low CRC unsigned char initialized */
unsigned int uIndex ; /* will index into CRC lookup*/
/* table*/
while (usDataLen--) /* pass through message buffer */
{
uIndex = uchCRCHi ^ *puchMsg ; /* calculate the CRC */
uchCRCHi = uchCRCLo ^ auchCRCHi[uIndex];
uchCRCLo = auchCRCLo[uIndex] ;
}

return ((uchCRCHi<<8)|uchCRCLo) ;
}

static BYTE TABLE1[256]; /* crc16 values */
static BYTE TABLE2[256]; /* crc16 values */

/*
crc_init: prepare crc16 preset tables
must be called once at init
(before any crc calculation)
*/

void crc_init (void)
{
WORD mask, bit, crc, mem;

for( mask = 0; mask < 0x100; mask ) {
crc = mask;
for( bit = 0; bit < 8; bit ) {
mem = crc & 0x0001 ;
crc /= 2;
if ( mem != 0 ) crc ^= POLY_CRC16 ;
}
TABLE2[mask] = crc & 0xff;
TABLE1[mask] = crc >> 8;
}
}

/*
crc_make: calculates a crc16
size: size of the frame (including header)
buff: pointer to the first byte of the frame
(slave number)
return: CRC16 in MOTOROLA format (high byte / low byte)
*/

WORD crc_make (WORD size, BYTE *buff)
{
BYTE car, i;
BYTE crc[2];

crc[0] = 0xff;
crc[1] = 0xff;
for ( i = 0; i < size; i ) {
car = buff[i];
car ^= crc[0];
crc[0] = crc[1] ^ TABLE2[car];
crc[1] = TABLE1[car];
}
return (*(WORD*)(&crc[0]));
}

#pragma small
#include <reg52.h>
unsigned int CRC_16(unsigned int c,unsigned char d);
unsigned int crc16=0;

void main(void)
{
// unsigned char crcbuff[] = {31,3,0,1,0,7};
unsigned char crcbuff[] = "123456789";
unsigned char *p;
// unsigned int crc16 = 0xffff;
p=crcbuff;
while(*p !='/0')
{
crc16 = CRC_16(crc16,*p );
}
p=crcbuff;
}

unsigned int CRC_16(unsigned int c,unsigned char d)
{
unsigned int data e;
unsigned char data f;
e = c^(unsigned int)d;
for(f=0;f<8;f )
{
if(e&1)
{
e >>= 1;
e ^= 0xa001;
}
else e >>= 1;
}
return e;
}
// 使用字符串"123456789"测试,crc16初始值为0时
// 结果为0xbb3d 符合crc caculator

unsigned int Crc16(unsigned char *ptr, unsigned char len)
{
unsigned int crc;
unsigned char da;

crc=0;
while(len--!=0)
 {
   da=crc>>12;
   crc<<=4;
   crc^=crc_ta[da^(*ptr/16)];
                             
   da=crc>>12;
   crc<<=4;
   crc^=crc_ta[da^(*ptr&0x0f)];
   ptr++;
}
return(crc);
}