辛亥百年纪念 - 产品组件系列03

“天下为公”

---------------------------

《CRC32读取/写入》

此组件目的：计算文件的CRC32值。

此组件用途：CRC32

==Code=========

UCRC.pas

(*--------------------------------------------------------------------------
Delphi菜鸟XiaoBin  2006.5.31于黑龙江草甸子
 http://blog.csdn.net/xiaobin_hlj80 
veic_2005@163.com
--------------------------------------------------------------------------*)

unit UCRC32;

interface

uses
Windows, SysUtils, Classes, Udefine;

type
CRC32array=array[0..255]of Longint;

var
crc32table:CRC32array;

procedure generateCRC32Array;
function calculateCRC32Number(filePath1:WideString):DWORD;stdcall;
procedure saveFCNFile(saveFile1,CheckFilePath:WideString);stdcall;
function readFCNFile(loadFile1:WideString):DWORD;stdcall;

implementation

procedure generateCRC32Array;
var
i11,j22,crc:longword;
begin
for i11:=0 to 256 do
begin
crc:=i11;

for j22:=0 to 8 do
begin
if (crc and 1)=1 then
begin
crc:=(crc shr 1)xor $EDB88320;
end
else
begin
crc:=crc shr 1;
end;
end;
crc32table[i11]:=crc;
end;

end;

function calculateCRC32Number(filePath1:WideString):DWORD;
var
crc32:DWORD;
len:longword;
i1:integer;
fs:TFileStream;
Buffer: array[1..8192] of Byte;
begin
generateCRC32Array;
try
fs:=TFileStream.Create(filePath1,fmOpenRead);
len:=fs.Read(Buffer,sizeof(Buffer));
crc32:=$ffffffff;
for i1:=1 to len do
begin
crc32:=((crc32 shr 8)and $ffffff)xor crc32table[(crc32 xor dword(Buffer[i1]))and $ff];
end;
finally
fs.Free;
end;
Result:=crc32;
end;

procedure saveFCNFile(saveFile1,CheckFilePath:WideString);
var
fileStream1:TFileStream;
begin
DeleteFile(saveFile1);
If Not FileExists(saveFile1) Then
Begin
try
fileStream1:= TFileStream.Create(saveFile1, fmCreate);
FileHead.Version := '1.0.0.3';
FileHead.author:='xiaobin';
FileHead.CRC32:=calculateCRC32Number(CheckFilePath);
Filehead.UpdateDate := Now;
fileStream1.Write(FileHead, SizeOf(FileHead));
finally
fileStream1.Free;
end;
End;
end;

function readFCNFile(loadFile1:WideString):DWORD;stdcall;
var
fileStream2:TFileStream;
begin
try
fileStream2:=TFileStream.Create(loadFile1,fmOpenRead);
fileStream2.Read(FileHead,sizeof(FileHead));
Result:=FileHead.CRC32;
finally
fileStream2.Free;
end;
end;

end.

工程文件fcn.dpr

(*--------------------------------------------------------------------------
Delphi菜鸟XiaoBin  2006.5.31于黑龙江草甸子
 http://blog.csdn.net/xiaobin_hlj80 
veic_2005@163.com
--------------------------------------------------------------------------*)

library FCN;

uses
SysUtils,
Classes,
Udefine in 'Udefine.pas',
UCRC32 in 'UCRC32.pas';

{$R *.res}

EXPORTS
saveFCNFile name 'saveFCN',
readFCNFile name 'readFCN',
calculateCRC32Number name 'calCRC32';

begin
end.