Чтение сектора

function __Mul(a,b: DWORD; var HiDWORD: DWORD): DWORD; // Result = LoDWORD
asm
   mul edx
   mov [ecx],edx
end;
 
function ReadSectors(drive:char;StartingSector, SectorCount: DWORD;
                       Buffer: Pointer; BytesPerSector: DWORD): DWORD;
var
   hFile: THandle;
   br,TmpLo,TmpHi: DWORD;
begin
     Result := 0;
     hFile:=CreateFile(PChar('\\.\'+Drive+':'),GENERIC_READ or GENERIC_WRITE, FILE_SHARE_WRITE or FILE_SHARE_READ,
                        nil, CREATE_NEW, FILE_ATTRIBUTE_NORMAL or FILE_FLAG_OVERLAPPED, 0);
     if hFile = INVALID_HANDLE_VALUE then
      Exit;
     TmpLo:=__Mul(StartingSector,BytesPerSector,TmpHi);
     if SetFilePointer(hFile,TmpLo,@TmpHi,FILE_BEGIN) = TmpLo then
      begin
           SectorCount:=SectorCount*BytesPerSector;
           if ReadFile(hFile,Buffer^,SectorCount,br,nil) then
            Result:=br;
      end;
     CloseHandle(hFile);
end;
{-----------------------------ПРОЧИТАТЬ СЕКТОР---------------------------------}
procedure TForm1.ReadSectorBtnClick(Sender: TObject);
var
   buf:array of byte;
   i,j:integer;
   drive:char;
begin
     drive:=Drivecombobox1.drive;
     SetLength(buf,512);
     if ReadSectors(drive,strtoint(edit1.text),1,pointer(buf),512)=0 then
      showmessage('Ошибка доступа')
     else
      begin
           StringGrid1.RowCount:=round(length(buf)/15)-1;
           for i:=0 to round(length(buf)/16) do
            StringGrid1.Cells[0,i+1]:=inttohex(i*16,3);
           for i:=1 to round(length(buf)/16) do
            for j:=1 to 16 do
             StringGrid1.Cells[j,i]:=IntToHex(buf[16*(i-1)+j-1],2);
      end;
      Finalize(buf);
end;

function ReadSectors(drive:char;StartingSector, SectorCount: DWORD;
                       Buffer: Pointer; BytesPerSector: DWORD): DWORD;
var
   hFile: THandle;
   br,TmpLo,TmpHi: DWORD;
begin
     Result := 0;
     hFile:=CreateFile(PChar('\\.\'+Drive+':'), GENERIC_READ, FILE_SHARE_WRITE or FILE_SHARE_READ,
                        nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
     if hFile = INVALID_HANDLE_VALUE then
      Exit;
     TmpLo:=__Mul(StartingSector,BytesPerSector,TmpHi);
     if SetFilePointer(hFile, TmpLo, @TmpHi, FILE_BEGIN) = TmpLo then
      begin
           SectorCount:=SectorCount*BytesPerSector;
           if ReadFile(hFile, Buffer^, SectorCount, br, nil) then
            Result:=br;
      end;
     CloseHandle(hFile);
end;

     if ReadSectors(drive, StrToInt(edit1.text), 1, @buf[0], 512) = 0 then