[Karsh]

вот CRC:

Код:

function GetCRC(FName: string): DWORD;
var
  F: HWND;
  L, nSize: DWORD;
  Buffer: array[0..512] of Byte;
  i: integer;
begin
  F:= CreateFile(PChar(FName), GENERIC_READ, FILE_SHARE_READ, nil, OPEN_EXISTING, 0, 0);
  L:= 0;
  while nSize > 0 do
  begin
    ReadFile(F, Buffer, SizeOf(Buffer), nSize, nil);
    for i:=0 to nSize-1 do L:= L+Buffer[i];
  end;
  CloseHandle(F);
  Result:= L;
end;

и CRC32:

Код:

const
  CRCPOLY = $EDB88320;

var
  CRCTable: array[0..512] of Longint;

procedure BuildCRCTable;
var
  i, j: Word;
  r: DWORD;
begin
  FillChar(CRCTable, SizeOf(CRCTable), 0);
  for i:= 0 to 255 do
  begin
    r:= i shl 1;
    for j:= 8 downto 0 do
      if (r and 1) <> 0 then
        r:= (r Shr 1) xor CRCPOLY
      else
        r:= r shr 1;
    CRCTable[i]:= r;
  end;
end;

function RecountCRC(b: byte; CrcOld: Longint): Longint;
begin
  RecountCRC:= CRCTable[byte(CrcOld xor Longint(b))] xor ((CrcOld shr 8) and $00FFFFFF)
end;

function GetCRC32(FileName: string): DWORD;
var
  Buffer: PChar;
  f: File of Byte;
  b: array[0..255] of Byte;
  CRC: DWORD;
  e, i: Integer;
begin
  BuildCRCTable;
  CRC:= $FFFFFFFF;
  AssignFile(F, FileName);
  FileMode:= 0;
  Reset(F);
  GetMem(Buffer, SizeOf(B));
  repeat
    FillChar(b, SizeOf(b), 0);
    BlockRead(F, b, SizeOf(b), e);
    for i := 0 to (e-1) do
     CRC:= RecountCRC(b[i], CRC);
  until (e < 255) or (IOresult <> 0);
  FreeMem(Buffer, SizeOf(B));
  CloseFile(F);
  CRC:= Not CRC;
  Result:= CRC;
end;