unit CRC32Verify;
interface
uses
Windows, Messages, SysUtils, Classes, Forms;
CONST
table: ARRAY[0..255] OF DWORD =
($00000000, $77073096, $EE0E612C, $990951BA,
$076DC419, $706AF48F, $E963A535, $9E6495A3,
$0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988,
$09B64C2B, $7EB17CBD, $E7B82D07, $90BF1D91,
$1DB71064, $6AB020F2, $F3B97148, $84BE41DE,
$1ADAD47D, $6DDDE4EB, $F4D4B551, $83D385C7,
$136C9856, $646BA8C0, $FD62F97A, $8A65C9EC,
$14015C4F, $63066CD9, $FA0F3D63, $8D080DF5,
$3B6E20C8, $4C69105E, $D56041E4, $A2677172,
$3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B,
$35B5A8FA, $42B2986C, $DBBBC9D6, $ACBCF940,
$32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59,
$26D930AC, $51DE003A, $C8D75180, $BFD06116,
$21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F,
$2802B89E, $5F058808, $C60CD9B2, $B10BE924,
$2F6F7C87, $58684C11, $C1611DAB, $B6662D3D,
$76DC4190, $01DB7106, $98D220BC, $EFD5102A,
$71B18589, $06B6B51F, $9FBFE4A5, $E8B8D433,
$7807C9A2, $0F00F934, $9609A88E, $E10E9818,
$7F6A0DBB, $086D3D2D, $91646C97, $E6635C01,
$6B6B51F4, $1C6C6162, $856530D8, $F262004E,
$6C0695ED, $1B01A57B, $8208F4C1, $F50FC457,
$65B0D9C6, $12B7E950, $8BBEB8EA, $FCB9887C,
$62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65,
$4DB26158, $3AB551CE, $A3BC0074, $D4BB30E2,
$4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB,
$4369E96A, $346ED9FC, $AD678846, $DA60B8D0,
$44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9,
$5005713C, $270241AA, $BE0B1010, $C90C2086,
$5768B525, $206F85B3, $B966D409, $CE61E49F,
$5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4,
$59B33D17, $2EB40D81, $B7BD5C3B, $C0BA6CAD,
$EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A,
$EAD54739, $9DD277AF, $04DB2615, $73DC1683,
$E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8,
$E40ECF0B, $9309FF9D, $0A00AE27, $7D079EB1,
$F00F9344, $8708A3D2, $1E01F268, $6906C2FE,
$F762575D, $806567CB, $196C3671, $6E6B06E7,
$FED41B76, $89D32BE0, $10DA7A5A, $67DD4ACC,
$F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5,
$D6D6A3E8, $A1D1937E, $38D8C2C4, $4FDFF252,
$D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B,
$D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60,
$DF60EFC3, $A867DF55, $316E8EEF, $4669BE79,
$CB61B38C, $BC66831A, $256FD2A0, $5268E236,
$CC0C7795, $BB0B4703, $220216B9, $5505262F,
$C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04,
$C2D7FFA7, $B5D0CF31, $2CD99E8B, $5BDEAE1D,
$9B64C2B0, $EC63F226, $756AA39C, $026D930A,
$9C0906A9, $EB0E363F, $72076785, $05005713,
$95BF4A82, $E2B87A14, $7BB12BAE, $0CB61B38,
$92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21,
$86D3D2D4, $F1D4E242, $68DDB3F8, $1FDA836E,
$81BE16CD, $F6B9265B, $6FB077E1, $18B74777,
$88085AE6, $FF0F6A70, $66063BCA, $11010B5C,
$8F659EFF, $F862AE69, $616BFFD3, $166CCF45,
$A00AE278, $D70DD2EE, $4E048354, $3903B3C2,
$A7672661, $D06016F7, $4969474D, $3E6E77DB,
$AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0,
$A9BCAE53, $DEBB9EC5, $47B2CF7F, $30B5FFE9,
$BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6,
$BAD03605, $CDD70693, $54DE5729, $23D967BF,
$B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94,
$B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D);
// Use CalcCRC32 as a procedure so CRCValue can be passed in but
// also returned. This allows multiple calls to CalcCRC32 for
// the "same" CRC-32 calculation.
type TProgressEvent=Procedure (Sender:TObject; Progress :integer; Error:dword; var Continue:boolean) of object;
type
TCRC = class(TComponent)
private
{ Private declarations }
FProgressBlockSize:word;
FContinue,InProgress:boolean;
FProgressEvent:TProgressEvent;
protected
{ Protected declarations }
public
{ Public declarations }
Constructor Create(AOwner : TComponent); override;
destructor Destroy; override;
procedure CheckCRC(P: Pointer; ByteCount: DWORD; VAR CRCValue: DWORD);
// The following is a little cryptic (but executes very quickly).
// The algorithm is as follows:
// 1. exclusive-or the input byte with the low-order byte of
// the CRC register to get an INDEX
// 2. shift the CRC register eight bits to the right
// 3. exclusive-or the CRC register with the contents of
// Table[INDEX]
// 4. repeat steps 1 through 3 for all bytes;
function CheckFileCRC(FileName: string):DWord;
function CheckStringCRC(Str:String):DWord;
published
{ Published declarations }
property ProgressBlockSize:word read FProgressBlockSize write FProgressBlockSize default 4096;
property OnProgress:TProgressEvent read FProgressEvent write FProgressEvent;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('Samples', [TCRC]);
end;
{ TCRC }
procedure TCRC.CheckCRC(P: Pointer; ByteCount: DWORD; var CRCValue: DWORD);
VAR
i: DWORD;
q: ^BYTE;
BEGIN
q := p;
FContinue:=true;
if ByteCount<1 then
begin
CRCValue:=0;
Exit;
end;
FOR i := 0 TO ByteCount-1 DO
BEGIN
Application.ProcessMessages;
if i mod FProgressBlockSize=0 then
if Assigned(FProgressEvent) then FProgressEvent(self,i,Error,FContinue);
if not FContinue then exit;
CRCvalue := (CRCvalue SHR 8) XOR
Table[ q^ XOR (CRCvalue AND $000000FF) ];
INC(q)
END;
{CalcCRC32}
end;
function TCRC.CheckFileCRC(FileName:string):DWord;
VAR
Stream: TMemoryStream; CRCValue:DWord;
BEGIN
CRCValue := $FFFFFFFF;
Stream := TMemoryStream.Create;
TRY
TRY
Stream.LoadFromFile(FileName);
IF Stream.Size > 0
THEN CheckCRC (Stream.Memory, Stream.Size, CRCvalue)
ELSE begin Result:=0; Exit; end;
EXCEPT
ON E: EReadError DO
Result := 0;
END;
Result := NOT CRCvalue;
FINALLY
Stream.Free
END;
END {CalcFileCRC32};
function TCRC.CheckStringCRC(Str:string):DWord;
var CRCValue:DWord;
begin
if Str='' then begin Result:=0; Exit; end;
CRCValue:=$FFFFFFFF;
CheckCRC(PChar(Str),Length(Str),CRCValue);
Result:=not CRCValue;
end;
constructor TCRC.Create(AOwner: TComponent);
begin
inherited;
InProgress:=false;
FContinue:=true;
FProgressBlockSize:=4096;
end;
destructor TCRC.Destroy;
begin
inherited;
end;
end.