① crc8校驗：多項式二(0x07)為什麼是X8 + X2 + X + 1
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原 java實現 CRC8 校驗 多項式 x8+x2+x+1
DunnX閱讀數：3922018-12-19
物聯網 伺服器需要檢驗設備傳輸的數據，設備c語言寫的，CRC8 校驗多項式為 x8+x2+x+1，找了網路，必應。也沒有找到java CRC8 多項式 x8+x2+x+1的實現，能找到的都是x8+x5+x4+1的，後轉google，費了些功夫不過還好找到了。不說了，上代碼。
package com.smartsocket.utils;
/**
*
*
* @author zs
*/
public class CRC8Util {
/**
* CRC8 校驗 多項式 x8+x2+x+1
* @param b
* @param off
* @param len
* @return
*/
public static byte CRC8Check(final byte[] b, final int off, final int len){
byte result=0x00;
for (int i = 0; i < len; i++) {
result = CHECKSUM_TABLE[(result ^ (b[i + of
(byte) 0x95, (byte) 0x92, (byte) 0x9b, (byte) 0x9c, (byte) 0xb1, (byte) 0xb6, (byte) 0xbf, (byte) 0xb8, (byte) 0xad,
(byte) 0xaa, (byte) 0xa3, (byte) 0xa4, (byte) 0xf9, (byte) 0xfe, (byte) 0xf7, (byte) 0xf0, (byte) 0xe5, (byte) 0xe2,
② 用C語言編寫，crc8校驗9個位元組的數據，生成多項式為x8+x2+x+1，
//8bitCRC(X(8)+X(2)+X(1)+1)
typedefunsignedlongDWORD;
typedefunsignedshortWORD;
typedefunsignedcharBYTE;
#defineAL2_FCS_COEF((1<<7)+(1<<6)+(1<<5))
//data為指向校驗數據的指針，length為長度，返回一個位元組的校驗碼
BYTEGetCrc8(unsignedchar*data,intlength)
{
BYTEcFcs=0;
inti,j;
for(i=0;i<length;i++)
{
cFcs^=data[i];
for(j=0;j<8;j++)
{
if(cFcs&1)
{
cFcs=(BYTE)((cFcs>>1)^AL2_FCS_COEF);
}
else
{
cFcs>>=1;
}
}
}
returncFcs;
}
③ 大俠給我個完整的crc 程序 用C語言實現的，能在PC機上運行的。我馬上拿出100分。。。
樓主程序中調用函數cal_crc()的方式不正確。函數cal_crc()用於計算輸入串的校驗碼，因此函數輸入參數包含輸入串及該串的長度。
建議將main()函數修改為：
#include <string.h>
void main()
{
unsigned char buf[] = "ABCDEFG1234567"; // 輸入串
unsigned char len = 14; // 輸入串的長度
unsigned int crc;
crc = cal_crc(buf, len);
}
最後需要注意的是，輸入串的長度不能大於256個位元組。上述例子程序中假定了輸入串為字元串，實際上，還可以是位元組串，此時變數len表示位元組串的包含的位元組個數。
④ C語言實現CRC校驗
把我知道的說一下：
碼流後面加8個0可以用移位得到（碼流<<8；）
單次異或運算可以用運算符:^（運算符兩邊為常數）
由於你校驗的是5個位元組，且要多次異或運算，所以得藉助數組，或其它的數據結果才能完成。
最後問一下你是做硬體的嗎
⑤ 有關CRC—8的程序
/////crc.c
//*****************************************************************************
//
// The CRC table for the polynomial C(x) = x^8 + x^2 + x + 1 (CRC-8-CCITT).
//
//*****************************************************************************
static const unsigned char g_pucCrc8CCITT[256] =
{
0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15,
0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D,
0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65,
0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D,
0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5,
0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD,
0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85,
0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD,
0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2,
0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA,
0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2,
0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A,
0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32,
0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A,
0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42,
0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A,
0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C,
0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4,
0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC,
0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4,
0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C,
0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44,
0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C,
0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34,
0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B,
0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63,
0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B,
0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13,
0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB,
0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,
0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB,
0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3
};
//*****************************************************************************
//
// This macro executes one iteration of the CRC-8-CCITT.
//
//*****************************************************************************
#define CRC8_ITER(crc, data) g_pucCrc8CCITT[(unsigned char)((crc) ^ (data))]
//*****************************************************************************
//
//! Calculates the CRC-8-CCITT of an array of bytes.
//!
//! \param ucCrc is the starting CRC-8-CCITT value.
//! \param pucData is a pointer to the data buffer.
//! \param ulCount is the number of bytes in the data buffer.
//!
//! This function is used to calculate the CRC-8-CCITT of the input buffer.
//! The CRC-8-CCITT is computed in a running fashion, meaning that the entire
//! data block that is to have its CRC-8-CCITT computed does not need to be
//! supplied all at once. If the input buffer contains the entire block of
//! data, then \b ucCrc should be set to 0. If, however, the entire block of
//! data is not available, then \b ucCrc should be set to 0 for the first
//! portion of the data, and then the returned value should be passed back in
//! as \b ucCrc for the next portion of the data.
//!
//! For example, to compute the CRC-8-CCITT of a block that has been split into
//! three pieces, use the following:
//!
//! \verbatim
//! ucCrc = Crc8CCITT(0, pucData1, ulLen1);
//! ucCrc = Crc8CCITT(ucCrc, pucData2, ulLen2);
//! ucCrc = Crc8CCITT(ucCrc, pucData3, ulLen3);
//! \endverbatim
//!
//! Computing a CRC-8-CCITT in a running fashion is useful in cases where the
//! data is arriving via a serial link (for example) and is therefore not all
//! available at one time.
//!
//! \return The CRC-8-CCITT of the input data.
//
//*****************************************************************************
unsigned char
Crc8CCITT(unsigned char ucCrc, const unsigned char *pucData,
unsigned long ulCount)
{
unsigned long ulTemp;
//
// If the data buffer is not short-aligned, then perform a single step of
// the CRC to make it short-aligned.
//
if((unsigned long)pucData & 1)
{
//
// Perform the CRC on this input byte.
//
ucCrc = CRC8_ITER(ucCrc, *pucData);
//
// Skip this input byte.
//
pucData++;
ulCount--;
}
//
// If the data buffer is not word-aligned and there are at least two bytes
// of data left, then perform two steps of the CRC to make it word-aligned.
//
if(((unsigned long)pucData & 2) && (ulCount > 1))
{
//
// Read the next short.
//
ulTemp = *(unsigned short *)pucData;
//
// Perform the CRC on these two bytes.
//
ucCrc = CRC8_ITER(ucCrc, ulTemp);
ucCrc = CRC8_ITER(ucCrc, ulTemp >> 8);
//
// Skip these input bytes.
//
pucData += 2;
ulCount -= 2;
}
//
// While there is at least a word remaining in the data buffer, perform
// four steps of the CRC to consume a word.
//
while(ulCount > 3)
{
//
// Read the next word.
//
ulTemp = *(unsigned long *)pucData;
//
// Perform the CRC on these four bytes.
//
ucCrc = CRC8_ITER(ucCrc, ulTemp);
ucCrc = CRC8_ITER(ucCrc, ulTemp >> 8);
ucCrc = CRC8_ITER(ucCrc, ulTemp >> 16);
ucCrc = CRC8_ITER(ucCrc, ulTemp >> 24);
//
// Skip these input bytes.
//
pucData += 4;
ulCount -= 4;
}
//
// If there is a short left in the input buffer, then perform two steps of
// the CRC.
//
if(ulCount > 1)
{
//
// Read the short.
//
ulTemp = *(unsigned short *)pucData;
//
// Perform the CRC on these two bytes.
//
ucCrc = CRC8_ITER(ucCrc, ulTemp);
ucCrc = CRC8_ITER(ucCrc, ulTemp >> 8);
//
// Skip these input bytes.
//
pucData += 2;
ulCount -= 2;
}
//
// If there is a final byte remaining in the input buffer, then perform a
// single step of the CRC.
//
if(ulCount != 0)
{
ucCrc = CRC8_ITER(ucCrc, *pucData);
}
//
// Return the resulting CRC-8-CCITT value.
//
return(ucCrc);
}
⑥ CRC8位 C語言轉匯編
你可以參考：
//CRC校驗子程序開始
crc_jiaoyan:
mov 20h,#0xff
mov 21h,#0xff
mov 12h,#0x0d
mov 11h,#0x08
mov r0,#0x34
zijiekaishi:
mov a,21h
xrl a,@r0
kaishi:
rrc a
mov 21h,a
mov 10h,c
clr c
mov a,20h
rrc a
mov 0fh,c
mov 20h,a
anl 20h,#0x7f
jnb 10h,next
xrl 21h,#0x01
xrl 20h,#0xa0
next:
mov a,21h
djnz 11h,kaishi
mov 11h,#0x08
inc r0
djnz 12h,zijiekaishi
mov 42h,20h
mov 41h,21h
ret
//CRC校驗子程序結束
⑦ 查表法計算CRC碼的C程序設計，生成多項式為x8+x2+x+1
生成多項式：G(X)=X^8+X^2+X+1轉化為100000111 =0x1070
#define POLY (0x1070U << 3)
u8 crc8(u16 data)
{
int i;
for(i = 0; i < 8; i++) {
if (data & 0x8000)
data = data ^ POLY;
data = data << 1;
}
return (u8)(data >> 8);
}