// CRC32 calculates a cyclic redundancy code (CRC), known as CRC-32, using
// a byte-wise algorithm.
//
// (C) Copyright 1989, 1995-1996, 1999 Earl F. Glynn, Overland Park, KS.
// All Rights Reserved.
//
// This UNIT was derived from the CRCT FORTRAN 77 program given in
// "Byte-wise CRC Calculations" by Aram Perez in IEEE Micro, June 1983,
// pp. 40-50. The constants here are for the CRC-32 generator polynomial,
// as defined in the Microsoft Systems Journal, March 1995, pp. 107-108
//
// This CRC algorithm emphasizes speed at the expense of the 256-element
// lookup table.
//
// Updated for Delphi 4 dynamic arrays and stream I/O. July 1999.
UNIT CRC32;
INTERFACE
USES
Windows; // DWORD for D3/D4 compatibility
TYPE
{$IFDEF VER130} // This is a bit awkward
// 8-byte integer
TInteger8 = Int64; // Delphi 5
{$ELSE}
{$IFDEF VER120}
TInteger8 = Int64; // Delphi 4
{$ELSE}
TInteger8 = COMP; // Delphi 2 or 3
{$ENDIF}
{$ENDIF}
PROCEDURE CalcCRC32 (p: pointer; ByteCount: DWORD; VAR CRCvalue: DWORD);
PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: DWORD;
VAR TotalBytes: TInteger8;
VAR error: WORD);
IMPLEMENTATION
USES
{$IFDEF StreamIO}
SysUtils, // SysErrorMessage
{$ENDIF}
Dialogs, // ShowMessage
Classes, // TMemoryStream
LongFilenameOperations; // added by ViaThinkSoft
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.
PROCEDURE CalcCRC32 (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
VAR
i: DWORD;
q: ^BYTE;
BEGIN
q := p;
FOR i := 0 TO ByteCount-1 DO BEGIN
CRCvalue := (CRCvalue SHR 8) XOR
Table[ q^ XOR (CRCvalue AND $000000FF) ];
INC(q)
END
END {CalcCRC32};
{$IFDEF StreamIO} // Contemporary method using TMemoryStream
// The CRC-32 value calculated here matches the one from the PKZIP program.
// Use MemoryStream to read file in binary mode.
PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: DWORD;
VAR TotalBytes: TInteger8;
VAR error: WORD);
VAR
Stream: TMemoryStream;
BEGIN
error := 0;
CRCValue := $FFFFFFFF;
Stream := TMemoryStream.Create;
TRY
TRY
Stream.LoadFromFile(FromName);
IF Stream.Size > 0
THEN CalcCRC32 (Stream.Memory, Stream.Size, CRCvalue)
EXCEPT
ON E: EReadError DO
error := 1
END;
CRCvalue := NOT CRCvalue
FINALLY
Stream.Free
END;
END {CalcFileCRC32};
{$ELSE} // "older" BlockRead method
// The CRC-32 value calculated here matches the one from the PKZIP program.
// Use BlockRead to read file in binary mode.
PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: DWORD;
VAR TotalBytes: TInteger8;
VAR error: WORD);
CONST
BufferSize = 32768;
TYPE
BufferIndex = 0..BufferSize-1;
TBuffer = ARRAY[BufferIndex] OF BYTE;
pBuffer = ^TBuffer;
VAR
BytesRead: INTEGER;
FromFile : FILE;
FromFile2: THandle;
IOBuffer : pBuffer;
BEGIN
New(IOBuffer);
TRY
FileMode := 0; {Turbo default is 2 for R/W; 0 is for R/O}
CRCValue := $FFFFFFFF;
if Length(FromName) >= MAX_PATH then
begin
MyASSIGNFile (FromFile2,FromName);
MyRESET (FromFile2);
error := GetLastError;
end
else
begin
ASSIGN (FromFile,FromName);
{$I-} RESET (FromFile,1); {$I+}
error := IOResult;
end;
IF error = 0
THEN BEGIN
TotalBytes := 0;
REPEAT
if Length(FromName) >= MAX_PATH then // [sic!] "greater equal" is correct! The Delphi functions fail if the filename is 260 or greater, but Microsoft says MAX_PATH is the maximum (legal) length!
begin
MyBlockRead (FromFile2, IOBuffer^, BufferSize, BytesRead);
end
else
begin
{$I-}
BlockRead (FromFile, IOBuffer^, BufferSize, BytesRead);
{$I+}
end;
error := IOResult;
IF (error = 0) AND (BytesRead > 0)
THEN BEGIN
CalcCRC32 (IOBuffer, BytesRead, CRCvalue);
TotalBytes := TotalBytes + BytesRead; // can't use INC with COMP
END
UNTIL (BytesRead = 0) OR (error > 0);
if Length(FromName) >= MAX_PATH then
begin
MyCLOSEFile (FromFile2)
end
else
begin
CLOSE (FromFile)
end;
END;
CRCvalue := NOT CRCvalue
FINALLY
Dispose(IOBuffer)
END
END {CalcFileCRC32};
{$ENDIF}
END {CRC32}.