CRC32生成码表方法实现。。。。。

Table:Array[0..255] of DWORD;

procedure MakeTable();

var

i,j,Crc:integer;

begin

for i:=0 to 255 do

begin

Crc:=i;

for j:=0 to 7 do

begin

if (Crc and 1)<>0 then

Crc:=(Crc shr 1) xor $EDB88320

else

Crc:=Crc shr 1;

end;

Table[i]:=Crc;

end;

end;

procedure GetCRC32File(FileName:string;var CRC32:DWORD);

var

F:file;

BytesRead:DWORD;

Buffer:array[1..65521] of Byte;

i:Word;

begin

FileMode :=0;

CRC32 :=$ffffffff;

{$I-}

AssignFile(F,FileName);

Reset(F,1);

if IoResult = 0 then

begin

repeat

BlockRead(F,Buffer,Sizeof(Buffer),BytesRead);

for i := 1 to BytesRead do

CRC32 := (CRC32 shr 8) xor Table[Buffer[i] xor (CRC32 and $000000ff)];

until BytesRead = 0;

end;

CloseFile(F);

{$I+}

CRC32 := not CRC32;

end;

function GetCrc32Str(s: string; Seed: LongInt):string;

var

Count: Integer;

CrcVal: LongInt;

begin

CrcVal := Seed;

for Count := 1 to Length(s) do

CrcVal := Table[Byte(CrcVal xor DWORD(Ord(s[Count])))] xor ((CrcVal shr 8) and $00FFFFFF);

Result := IntToHex(not(CrcVal), 8);

end;

调用：

procedure TForm1.Button1Click(Sender: TObject);

begin

MakeTable();

Edit1.Text:=GetCrc32Str('11111111',8);//这里取指定字符串的CRC32校验值;

end;

procedure TForm1.Button2Click(Sender: TObject);

var

FileStr:String;

crc: DWORD;

begin

MakeTable();

FileStr:=Application.ExeName;//这里取指定的文件的crc32校验值;

GetCRC32File(FileStr,crc);

if crc<>0 then

Edit2.Text:=PChar(IntToHex(crc,6));

end;