下面示出了其计算过程的流程图:
在用C语言编写CRC校验码的实现程序时我们应该注意,生成多项式 对应的十六进制数为0x18005,由于CRC寄存器左移过程中,移出的最高位为1时与 相异或,所以与16bit的CRC寄存器对应并塌圆的生成多项式的十六进制数可用0x8005表示。下面给出并行处理8bit数据流的C源程序:
unsigned short crc_dsp(unsigned short reg, unsigned char data_crc)
//reg为crc寄存器, data_crc为将要处理的8bit数据流
{
unsigned short msb//crc寄存器将移出的最高1bit
unsigned short data
unsigned short gx = 0x8005, i = 0//i为左移次数, gx为生成多项式
data = (unsigned short)data_crc
data = data <<8
reg = reg ^ data
do
{
msb = reg &0x8000
reg = reg <<1
if(msb == 0x8000)
{
reg = reg ^ gx
}
i++
}
while(i <8)
return (reg)
}
以上为处理每一个8bit数据流的子程序,在计衫扮算整个数据流的CRC校验码时,我们只需将CRC_reg的初值置为0x0000,求第一个8bit的CRC值,之后,即可将上次求得的CRC值和本次将要处理的8bit数据作为函数实参传递给上述子程序的形参进行处理即可,最终返回的reg值便是我们所想得到的整个数据流的CRC校验值。
unsigned short crc_dsp(unsigned short reg, unsigned char data_crc)//reg为crc寄迅岩存器, data_crc为将要处理的猜键8bit数据流
{
unsigned short msb//crc寄存器将移出的最高1bit
unsigned short data
unsigned short gx = 0x8005, i = 0//i为左移亩兆御次数, gx为生成多项式
data = (unsigned short)data_crc
data = data <<8
reg = reg ^ data
do
{
msb = reg &0x8000
reg = reg <<1
if(msb == 0x8000)
{
reg = reg ^ gx
}
i++
}
while(i <8)
return (reg)
}
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
}
static unsigned char auchCRCHi[]=
{
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
}
bool CRCDecToHex(unsigned char Destination[],unsigned char Source,const int DesLen,int &HexBit)
void UCToASCII(unsigned char Lo16[],int len)
unsigned short CRC16(unsigned char puchmsg[],unsigned short usdatalen)
int main()
{
//unsigned char buf[]={0x01,0xA8,0x98,0x42,0x65,0x74,0x74,0x65,0x72,0x17}
//unsigned char buf[]={0x07,0x11,0x41,0x00,0x53,0xB9,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03}
unsigned char buf[]={0x00,0x00,0x01,0x00,0x00,0x00,0x1A,0x00,0x1C,0x03}
//unsigned short Len=10
//unsigned short Len=19
unsigned short Len=10
unsigned char Lo=CRC16(buf,Len)%256
unsigned char Hi=CRC16(buf,Len)/256
unsigned char Lo16[4]={0}
unsigned char Hi16[4]={0}
printf("十进制:低字节Lo=%d\n十进制:高字节Hi=%d\n",Lo,Hi)
unsigned char temp=Lo
int ASCIILoLen=0
CRCDecToHex(Lo16,temp,4,ASCIILoLen)
UCToASCII(Lo16,ASCIILoLen)
printf(" 低字节:Lo16=")
for (int i=0i<ASCIILoLeni++)
printf("%c",Lo16[i])
printf("H\n")
temp=Hi
int ASCIIHiLen=0
CRCDecToHex(Hi16,temp,4,ASCIIHiLen)
UCToASCII(Hi16,ASCIIHiLen)
printf(" 高字节:Hi16=")
for (int I=0I<ASCIIHiLenI++)
printf("%c",Hi16[I])
printf("H\n")
return 1
}
//十进制转十六进制
bool CRCDecToHex(unsigned char Destination[],unsigned char Source,const int DesLen,int &HexBit)
{
unsigned char temp=Source
int i=DesLen-1
while(temp>=16)
{
Destination[i]=temp%16
printf("Lo[%d]=%d\n",i,Destination[i])
temp=temp/16
i--
}
Destination[i]=temp
printf("Lo[%d]=%d\n",i,Destination[i])
HexBit=DesLen-1-i+1
for(int a=i(a-i)<(DesLen-1-i+1)a++)
{
Destination[a-i]=Destination[a]
printf("移位后:Lo16[%d]=%d\n",a-i,Destination[a-i])
}
return true
}
//无符号字符型转ASCII码
void UCToASCII(unsigned char Lo16[],int len)
{
for(int i=0i<leni++)
{
if (Lo16[i]>=10)
{
switch (Lo16[i])
{
case 10:
Lo16[i]='A'break
case 11:
Lo16[i]='B'break
case 12:
Lo16[i]='C'break
case 13:
Lo16[i]='D'break
case 14:
Lo16[i]='E'break
case 15:
Lo16[i]='F'break
default: break
}
}
else
{
Lo16[i]+=48
}
}
}
unsigned short CRC16(unsigned char puchmsg[],unsigned short usdatalen)
{
unsigned char uchCRCHi=0xFF
unsigned char uchCRCLo=0xFF
unsigned short uIndex
unsigned short y=0
while(usdatalen--)
{
uIndex=uchCRCHi=(unsigned char)(uchCRCHi ^ puchmsg[y++])
uchCRCHi=(unsigned char)(uchCRCLo ^ auchCRCHi[uIndex])
uchCRCLo=auchCRCLo[uIndex]
}
return(unsigned short)(uchCRCLo+uchCRCHi*256)
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