Вычисление CRC-32 для файла

// The constants here are for the CRC-32 generator 
// polynomial, as defined in the Microsoft 
// Systems Journal, March 1995, pp. 107 - 108 
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); 
 
type 
//----------------------------------crc32---------------------------------- 
  {$IFDEF VER130}           // This is a bit awkward 
    // 8-byte integer 
    TInteger8 = Int64;     // Delphi 5 
  {$ELSE} 
  {$IFDEF VER120} 
    TInteger8 = Int64;     // Delphi 4 
  {$ELSE} 
    TInteger8 = COMP;      // Delphi  2 or 3 
  {$ENDIF} 
  {$ENDIF} 
//----------------------------------crc32---------------------------------- 
 
 
  // 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}; 
 
function CalcStringCRC32(s: string; out CRC32: DWORD): Boolean; 
var 
  CRC32Table: DWORD; 
begin 
  // Verify the table used to compute the CRCs has not been modified. 
  // Thanks to Gary Williams for this suggestion, Jan. 2003. 
  CRC32Table := $FFFFFFFF; 
  CalcCRC32(Addr(Table[0]), SizeOf(Table), CRC32Table); 
  CRC32Table := not CRC32Table; 
 
  if CRC32Table <> $6FCF9E13 then ShowMessage('CRC32 Table CRC32 is ' + 
      IntToHex(Crc32Table, 8) + 
      ', expecting $6FCF9E13') 
  else 
  begin 
    CRC32 := $FFFFFFFF; // To match PKZIP 
    if Length(s) > 0  // Avoid access violation in D4 
      then CalcCRC32(Addr(s[1]), Length(s), CRC32); 
    CRC32 := not CRC32; // To match PKZIP 
  end; 
end; 
 
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; 
 
procedure TForm1.Button1Click(Sender: TObject); 
var 
  s: string; 
  CRC32: DWORD; 
begin 
  s := 'Test String'; 
  if CalcStringCRC32(s, CRC32) then 
    ShowMessage(IntToStr(crc32)); 
end;

Взято с сайта https://www.swissdelphicenter.ch/en/tipsindex.php

{ **** UBPFD *********** by kladovka.net.ru ****
>> Быстрый алгоритм подсчета CRC32
 
Использован BASM.
 
Зависимости: нет
Автор:       Александр Шарахов, alsha@mailru.com, Москва
Copyright:   Александр Шарахов
Дата:        18 января 2003 г.
********************************************** }
 
unit CRCunit;
 
interface
function GetNewCRC(OldCRC: cardinal; StPtr: pointer; StLen: integer): cardinal;
procedure UpdateCRC(StPtr: pointer; StLen: integer; var CRC: cardinal);
function GetZipCRC(StPtr: pointer; StLen: integer): cardinal;
function GetFileCRC(const FileName: string): cardinal;
 
implementation
var
  CRCtable: array[0..255] of cardinal;
 
function GetNewCRC(OldCRC: cardinal; StPtr: pointer; StLen: integer): cardinal;
asm
  test edx,edx;
  jz @ret;
  neg ecx;
  jz @ret;
  sub edx,ecx; // Address after last element
 
  push ebx;
  mov ebx,0; // Set ebx=0 & align @next
@next:
  mov bl,al;
  xor bl,byte [edx+ecx];
  shr eax,8;
  xor eax,cardinal [CRCtable+ebx*4];
  inc ecx;
  jnz @next;
  pop ebx;
 
@ret:
end;
 
procedure UpdateCRC(StPtr: pointer; StLen: integer; var CRC: cardinal);
begin
  CRC:=GetNewCRC(CRC,StPtr,StLen);
end;
 
function GetZipCRC(StPtr: pointer; StLen: integer): cardinal;
begin
  Result:=not GetNewCRC($FFFFFFFF, StPtr, StLen);
end;
 
function GetFileCRC(const FileName: string): cardinal;
const
  BufSize = 64*1024;
var
  Fi: file;
  pBuf: PChar;
  Count: integer;
begin
  Assign(Fi,FileName);
  Reset(Fi,1);
  GetMem(pBuf,BufSize);
  Result:=$FFFFFFFF;
  repeat
    BlockRead(Fi,pBuf^,BufSize,Count);
    if Count=0 then break;
    Result:=GetNewCRC(Result,pBuf,Count);
  until false;
  Result:=not Result;
  FreeMem(pBuf);
  CloseFile(Fi);
end;
 
procedure CRCInit;
var
  c: cardinal;
  i, j: integer;
begin
  for i:=0 to 255 do begin
    c:=i;
    for j:=1 to 8 do if odd(c) then c:=(c shr 1) xor $EDB88320 else c:=(c shr 1);
    CRCtable[i]:=c;
  end;
end;
 
initialization
  CRCinit;
end. 

Пример использования:

uses
  CRCunit;
procedure TForm1.Button1Click(Sender: TObject);
const
  FileName='CRCunit.pas';
begin
  ShowMessage('CRC32 файла='+IntToHex(GetFileCRC(FileName),8));
  ShowMessage('CRC32 имени='+IntToHex(GetZipCRC(PChar(FileName),Length(FileName)),8));
end; 
 

{ **** UBPFD *********** by delphibase.endimus.com ****
>> Расчёт контрольной суммы файла CRC-32
 
Функция находит контрольную сумму файла FileName
(полное имя файла с путём). Если возникает ошибка
(файл не найден или его нельзя открыть для чтения)
выдаётся сообщение об этом. Если это не нужно
то удалить строки с выводом сообщения.
 
Зависимости: classes, Sysutils, Dialogs;
Автор:       MegaVolt, MegaVoltik@yahoo.com
Copyright:   :( Не помню :( Взято где то в сети
несколько доработано и после обсуждения в
Дата:        3 декабря 2002 г.
***************************************************** }
 
unit Crc32;
 
interface
 
uses
  classes, Sysutils, Dialogs;
 
function FileCRC32(const FileName: string): Cardinal;
function UpdateCRC32(InitCRC: Cardinal; BufPtr: Pointer; Len: Word): LongInt;
 
implementation
 
type
  CRCTable = array[0..255] of Cardinal;
 
const
  BufLen = 32768;
 
  CRC32Table: CRCTable =
  ($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, $04FDFF252,
    $D1BB67F1, $A6BC5767, $3FB506DD, $048B2364B,
    $D80D2BDA, $AF0A1B4C, $36034AF6, $041047A60,
    $DF60EFC3, $A867DF55, $316E8EEF, $04669BE79,
 
    $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);
 
var
  Buf: array[1..BufLen] of Byte;
 
function UpdateCRC32(InitCRC: Cardinal; BufPtr: Pointer; Len: Word): LongInt;
var
  crc: Cardinal;
  index: Integer;
  i: Cardinal;
begin
  crc := InitCRC;
  for i := 0 to Len - 1 do
  begin
    index := (crc xor Cardinal(Pointer(Cardinal(BufPtr) + i)^)) and $000000FF;
    crc := (crc shr 8) xor CRC32Table[index];
  end;
  Result := crc;
end;
 
function FileCRC32(const FileName: string): Cardinal;
var
  InFile: TFileStream;
  crc32: Cardinal;
  Res: Integer;
  BufPtr: Pointer;
begin
  BufPtr := @Buf;
  crc32 := $FFFFFFFF;
  try
    InFile := TFileStream.Create(FileName, fmShareDenyNone);
    Res := InFile.Read(Buf, BufLen);
    while (Res <> 0) do
    begin
      crc32 := UpdateCrc32(crc32, BufPtr, Res);
      Res := InFile.Read(Buf, BufLen);
    end;
    InFile.Destroy;
  except
    on E: Exception do
    begin
      if Assigned(InFile) then
        InFile.Free;
      ShowMessage(Format('При обработке файла [%s] вышла ' +
        'вот такая oшибочка [%s]', [FileName, E.Message]));
    end;
  end;
  Result := not crc32;
end;
 
end.
//Пример использования: 
 
var
  i: cardinal;
begin
  i := FileCRC32('c:\autoexec.bat');
  ShowMessage('Контрольная сумма файла = ' IntToStr(i));