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CRC8算法DELPHI源碼

來源:互聯網網民  2006-04-12 05:49:34  評論

最近做個程序需要用到CRC8校驗,網上找了一堆資料都看得頭暈腦脹的,最終還是搞不懂它的算法,慚愧。最後找了個C源碼請高手翻譯成DELPHI的才解決問題。在這感謝老鸨。。他寫的DELPHI程序如下:

unit Crc8;

interface

Uses

Classes, Windows;

Function Crc_8n(p : array of BYTE; len : BYTE) : Byte;

implementation

Function Crc_8n(p : array of BYTE; len : BYTE) : Byte;

Var

j, cbit, aout, crc, crc_a, crc_b : Byte;

i : integer;

begin

crc := 0;

i := 0;

// 取移位的位

repeat

crc_a := p[i];

inc(i);

j := 8;

cbit := 1;

repeat

crc_b := crc_a;

crc_b := crc_b xor crc; // ?????

aout := crc_b and cbit;

if aout<>0 then begin

crc := crc xor $18; // ?????

crc := crc shr 1;

crc := crc or $80;

end else begin

crc := crc shr 1;

end;

crc_a := crc_a shr 1;

dec(j);

until j = 0;

dec(len);

until len = 0;

result := crc;

end;

end.

=================================

unit main;

interface

uses

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

Dialogs, StdCtrls,

Crc8;

type

TForm1 = class(TForm)

Edit1: TEdit;

Memo1: TMemo;

Button1: TButton;

procedure Button1Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

const MinBase = 2;

MaxBase = 36;

function StrToNum (const s: string; base: Integer;

neg: Boolean; max: Integer): Integer;

// s = 要轉換的字符串

// base = 進制數

// neg = 是否爲負數

// max = 要轉換的最大數//

// 用法:

// i:= StrToNum (''00101101'', 2, false, MaxInt);

// i:= StrToNum (''002D'', 16, false, MaxInt);

// i:= StrToNum (''-45'', 10, true, MaxInt);

// i:= StrToNum (''ZZ'', 36, true, MaxInt);

//

var negate, done: Boolean;

i, len, digit, mmb: Integer;

c: Char;

mdb, res: Integer;

begin

res:= 0; i:= 1; digit:= 0;

if (base >= MinBase) and (base <= MaxBase) then begin

mmb:= max mod base;

mdb:= max div base;

len:= Length (s);

negate:= False;

while (i <= len) and (s[i] = ' ') do Inc (i);

if neg then begin

case s[i] of

'+': Inc (i);

'-': begin Inc (i); negate:= TRUE; end;

end; (* CASE *)

end; (* IF neg *)

done:= len > i;

while (i <= len) and done do begin

c:= Upcase (s[i]);

case c of

'0'..'9': digit:= ORD(c) - 48;

'A'..'Z': digit:= ORD(c) - 55;

else done:= FALSE

end; (* CASE *)

done:= done and (digit < base);

if done then begin

done:= (res < mdb) or ((res = mdb) and (digit <= mmb));

IF done then begin

res:= res * base + digit;

Inc (i);

end; (* IF done *)

end; (* IF done *)

end; (* WHILE *)

if negate then res:= - res;

end; (* IF done *)

Result:= res;

end;

procedure TForm1.Button1Click(Sender: TObject);

Var

S : String;

P : Array[0..255] of Byte;

Len : Byte;

R : Byte;

I : Integer;

begin

S := Edit1.Text;

if length(s) mod 2 = 1 then s := s + '0';

Memo1.Lines.Add(S + ' :');

for i:=1 to length(s) div 2 do begin

p[i-1] := BYTE(StrToNum(copy(s, (i-1)*2+1, 2), 16, false, 500));

Memo1.Lines.Add(IntToStr(I) + ' --> ' + IntToHex(p[i-1], 2));

end;

Len := length(s) div 2;

R := Crc_8n(P, Len);

Memo1.Lines.Add('Crc8 Result: ' + IntToHex(R, 2));

end;

end.

 
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  最近做個程序需要用到CRC8校驗,網上找了一堆資料都看得頭暈腦脹的,最終還是搞不懂它的算法,慚愧。最後找了個C源碼請高手翻譯成DELPHI的才解決問題。在這感謝 老鸨。。他寫的DELPHI程序如下: unit Crc8; interface Uses Classes, Windows; Function Crc_8n(p : array of BYTE; len : BYTE) : Byte; implementation Function Crc_8n(p : array of BYTE; len : BYTE) : Byte; Var j, cbit, aout, crc, crc_a, crc_b : Byte; i : integer; begin crc := 0; i := 0; // 取移位的位 repeat crc_a := p[i]; inc(i); j := 8; cbit := 1; repeat crc_b := crc_a; crc_b := crc_b xor crc; // ????? aout := crc_b and cbit; if aout<>0 then begin crc := crc xor $18; // ????? crc := crc shr 1; crc := crc or $80; end else begin crc := crc shr 1; end; crc_a := crc_a shr 1; dec(j); until j = 0; dec(len); until len = 0; result := crc; end; end. ================================= unit main; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, Crc8; type TForm1 = class(TForm) Edit1: TEdit; Memo1: TMemo; Button1: TButton; procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.dfm} const MinBase = 2; MaxBase = 36; function StrToNum (const s: string; base: Integer; neg: Boolean; max: Integer): Integer; // s = 要轉換的字符串 // base = 進制數 // neg = 是否爲負數 // max = 要轉換的最大數// // 用法: // i:= StrToNum (''00101101'', 2, false, MaxInt); // i:= StrToNum (''002D'', 16, false, MaxInt); // i:= StrToNum (''-45'', 10, true, MaxInt); // i:= StrToNum (''ZZ'', 36, true, MaxInt); // var negate, done: Boolean; i, len, digit, mmb: Integer; c: Char; mdb, res: Integer; begin res:= 0; i:= 1; digit:= 0; if (base >= MinBase) and (base <= MaxBase) then begin mmb:= max mod base; mdb:= max div base; len:= Length (s); negate:= False; while (i <= len) and (s[i] = ' ') do Inc (i); if neg then begin case s[i] of '+': Inc (i); '-': begin Inc (i); negate:= TRUE; end; end; (* CASE *) end; (* IF neg *) done:= len > i; while (i <= len) and done do begin c:= Upcase (s[i]); case c of '0'..'9': digit:= ORD(c) - 48; 'A'..'Z': digit:= ORD(c) - 55; else done:= FALSE end; (* CASE *) done:= done and (digit < base); if done then begin done:= (res < mdb) or ((res = mdb) and (digit <= mmb)); IF done then begin res:= res * base + digit; Inc (i); end; (* IF done *) end; (* IF done *) end; (* WHILE *) if negate then res:= - res; end; (* IF done *) Result:= res; end; procedure TForm1.Button1Click(Sender: TObject); Var S : String; P : Array[0..255] of Byte; Len : Byte; R : Byte; I : Integer; begin S := Edit1.Text; if length(s) mod 2 = 1 then s := s + '0'; Memo1.Lines.Add(S + ' :'); for i:=1 to length(s) div 2 do begin p[i-1] := BYTE(StrToNum(copy(s, (i-1)*2+1, 2), 16, false, 500)); Memo1.Lines.Add(IntToStr(I) + ' --> ' + IntToHex(p[i-1], 2)); end; Len := length(s) div 2; R := Crc_8n(P, Len); Memo1.Lines.Add('Crc8 Result: ' + IntToHex(R, 2)); end; end.
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