有关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)

}

最近项目中用到了跟硬件通信的crc8校验，花了点时间研究了一下python的crc8校验，但是一歼尘樱直没有找到好的技术突破。

google了一番，昨天测试了网上的几种方法都不正确，确定了氏丛使用crcmod库来实现，参考官方文档和国内的一遍文章，具体如下：

http://crcmod.sourceforge.net/crcmod.predefined.html#class-predefinedcrc

http://blog.csdn.net/snoop_lttx/article/details/53674657

其实python3 只需要3步即可实现crc8校验，官方有crc8，但是默认是crc-8不是我要找的crc-8-maxim，而crcmod库是支持多种crc8计算兄郑的。

下面我是采用crc-8-maxim算法的，多项式：x8+x5+x4+1（二进制为100110001），0x31

正确运行结果为：0xd6

下面我们使用在线crc校验工具测试一下：

http://www.ip33.com/crc.html

测试截图如下：

到此我们完成了crc8校验和。

目前有三种方式实现转换：

关于crc8的理论，本文不再赘述了。可以参考以下文章：

http://blog.csdn.net/haifengid/article/details/51753181

我给你delphi的饥枣CRC算法，烂歼拆这个文改腊件可以直接使用

unit Main

interface

uses

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,

StdCtrls

type

TForm1 = class(TForm)

Memo1: TMemo

Label1: TLabel

Label2: TLabel

Label3: TLabel

GenPoly8Edit: TEdit

GenPoly16Edit: TEdit

GenPoly32Edit: TEdit

TestCRC8Btn: TButton

TestCRC16Btn: TButton

TestCRC32Btn: TButton

CalCRC8Btn: TButton

CalCRC16Btn: TButton

CalCRC32Btn: TButton

CRC8ResultEdit: TEdit

CRC16ResultEdit: TEdit

CRC32ResultEdit: TEdit

procedure FormCreate(Sender: TObject)

procedure TestCRC16BtnClick(Sender: TObject)

procedure TestCRC8BtnClick(Sender: TObject)

procedure TestCRC32BtnClick(Sender: TObject)

procedure CalCRC16BtnClick(Sender: TObject)

procedure CalCRC8BtnClick(Sender: TObject)

procedure CalCRC32BtnClick(Sender: TObject)

private

public

end

var

Form1: TForm1

GenPoly32: DWord

GenPoly16: Word

GenPoly8: Byte

GenPoly4: Byte

CRC32Tab: array [0..255] of DWord

CRC16Tab: array [0..255] of Word

CRC8Tab : array [0..255] of Byte

implementation

{$R *.DFM}

function CalCRC16(data, crc, genpoly: Word): Word

var i: Integer

begin

crc := crc xor (data shl 8)

for i:=0 to 7 do

if (crc and $8000) <>0 then

crc := (crc shl 1) xor genpoly

else crc := crc shl 1

Result := crc

end

procedure InitCRC16Tab(genpoly: DWord)

var i: Integer

begin

for i:=0 to 255 do

CRC16Tab[i] := CalCRC16(i,0,genpoly)

end

function QuickCRC16(data, crc: Word): Word

begin

crc := CRC16Tab[(crc shr 8) xor data] xor (crc shl 8)

Result := crc

end

function CalCRC8(data, crc, genpoly: Byte): Byte

var i: Integer

begin

crc := crc xor data

for i:=0 to 7 do

if (crc and $01) <>0 then

crc := (crc shr 1) xor genpoly

else crc := crc shr 1

Result := crc

end

procedure InitCRC8Tab(genpoly: DWord)

var i: Integer

begin

for i:=0 to 255 do

CRC8Tab[i] := CalCRC8(i,0,genpoly)

end

function QuickCRC8(data, crc: Byte): Word

begin

crc := CRC8Tab[crc xor data]

Result := crc

end

function CalCRC32(data, crc, genpoly: DWord): DWord

var i: Integer

begin

crc := crc xor data

for i:=0 to 7 do

if (crc and $01) <>0 then

crc := (crc shr 1) xor genpoly

else crc := crc shr 1

Result := crc

end

procedure InitCRC32Tab(genpoly: DWord)

var i: Integer

begin

for i:=0 to 255 do

CRC32Tab[i] := CalCRC32(i,0,genpoly)

end

function QuickCRC32(data, crc: DWord): DWord

begin

crc := CRC32Tab[Byte(crc xor data)] xor (crc shr 8)

Result := crc

end

procedure TForm1.FormCreate(Sender: TObject)

begin

GenPoly8 := StrToInt(GenPoly8Edit.Text)

InitCRC8Tab(GenPoly8)

GenPoly16 := StrToInt(GenPoly16Edit.Text)

InitCRC16Tab(GenPoly16)

GenPoly32 := StrToInt(GenPoly32Edit.Text)

InitCRC32Tab(GenPoly32)

end

procedure TForm1.TestCRC16BtnClick(Sender: TObject)

var data, crc, crcstart: Word

begin

crcstart := $1234

Memo1.Clear

Memo1.Lines.Add('16bit CRC')

for data:=0 to 255 do

begin

crc := CalCRC16(data,crcstart,GenPoly16)

Memo1.Text := Memo1.Text + IntToHex(crc, 4) + ' '

end

Memo1.Lines.Add('')

Memo1.Lines.Add('16bit Quick CRC')

for data:=0 to 255 do

begin

crc := QuickCRC16(data,crcstart)

Memo1.Text := Memo1.Text + IntToHex(crc, 4) + ' '

end

end

procedure TForm1.TestCRC8BtnClick(Sender: TObject)

var data, crc, crcstart: Byte

begin

crcstart := $12

Memo1.Clear

Memo1.Lines.Add('8bit CRC')

for data:=0 to 255 do

begin

crc := CalCRC8(data,crcstart,GenPoly8)

Memo1.Text := Memo1.Text + IntToHex(crc, 2) + ' '

end

Memo1.Lines.Add('')

Memo1.Lines.Add('8bit Quick CRC')

for data:=0 to 255 do

begin

crc := QuickCRC8(data,crcstart)

Memo1.Text := Memo1.Text + IntToHex(crc, 2) + ' '

end

end

procedure TForm1.TestCRC32BtnClick(Sender: TObject)

var data, crc, crcstart: DWord

begin

crcstart := $12345678

Memo1.Clear

Memo1.Lines.Add('32bit CRC')

for data:=0 to 255 do

begin

crc := CalCRC32(data,crcstart,GenPoly32)

Memo1.Text := Memo1.Text + IntToHex(crc, 8) + ' '

end

Memo1.Lines.Add('')

Memo1.Lines.Add('32bit Quick CRC')

for data:=0 to 255 do

begin

crc := QuickCRC32(data,crcstart)

Memo1.Text := Memo1.Text + IntToHex(crc, 8) + ' '

end

end

function GetDataFromText(str: String): String

var i, p1, p2: Integer

begin

Result := ''

while str <>'' do

begin

i := 0

p1 := Pos(' ',str)

p2 := Pos(#13#10,str)

if p1=1 then

begin Delete(str,1,1)continueend

if p2=1 then

begin Delete(str,1,2)continueend

if (p1=0) and (p2=0) and (str<>'') then

begin

i := StrToIntDef('$'+str,0)

Delete(str,1,Length(str))

end

if ((p1>0) and (p2=0)) or

((p1>0) and (p2>0) and (p1<p2)) then

begin

i := StrToIntDef('$'+Copy(str,1,p1-1),0)

Delete(str,1,p1)

end

if ((p1=0) and (p2>0)) or

((p1>0) and (p2>0) and (p1>p2)) then

begin

i := StrToIntDef('$'+Copy(str,1,p2-1),0)

Delete(str,1,p2+1)

end

Result := Result + Chr(i)

end

end

procedure TForm1.CalCRC16BtnClick(Sender: TObject)

var

i: Integer

databuf: String

data, crc: Word

begin

databuf := GetDataFromText(Memo1.Text)

crc := 0

for i:=1 to Length(databuf) do

begin

data := Ord(databuf[i])

crc := CalCRC16(data,crc,GenPoly16)

end

CRC16ResultEdit.Text := 'CRC16 = ' + IntToHex(crc,4)

end

procedure TForm1.CalCRC8BtnClick(Sender: TObject)

var

i: Integer

databuf: String

data, crc: Byte

begin

databuf := GetDataFromText(Memo1.Text)

crc := 0

for i:=1 to Length(databuf) do

begin

data := Ord(databuf[i])

crc := CalCRC8(data,crc,GenPoly8)

end

CRC8ResultEdit.Text := 'CRC8 = ' + IntToHex(crc,2)

end

procedure TForm1.CalCRC32BtnClick(Sender: TObject)

var

i: Integer

databuf: String

data, crc: DWord

begin

databuf := GetDataFromText(Memo1.Text)

crc := 0

for i:=1 to Length(databuf) do

begin

data := Ord(databuf[i])

crc := CalCRC32(data,crc,GenPoly32)

end

CRC32ResultEdit.Text := 'CRC32 = ' + IntToHex(crc,8)

end

end.

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