[Code]
#IFNDEF Unicode
  #DEFINE CharSize 1
#ELSE
  #DEFINE CharSize 2
#ENDIF

type
  TSeekOrigin = (
    soBeginning,
    soCurrent,
    soEnd
  );

#IFDEF UNICODE
function BufferToAnsi(const Buffer: string): AnsiString;
var
  W: Word;
  I: Integer;
begin
  SetLength(Result, Length(Buffer) * 2);
  for I := 1 to Length(Buffer) do
  begin
    W := Ord(Buffer[I]);
    Result[(I * 2)] := Chr(W shr 8); // high byte
    Result[(I * 2) - 1] := Chr(Byte(W)); // low byte
  end;
end;
#ENDIF

function ReadStringFromFile(const FileName: string; Origin: TSeekOrigin; Offset, Length: Integer;
  var S: AnsiString): Boolean;
var
  Buffer: string;
  Stream: TFileStream;
begin
  Result := True;
  try
    Stream := TFileStream.Create(FileName, fmOpenRead);
    try
      Stream.Seek(Offset, Ord(Origin));
      SetLength(Buffer, Length div {#CharSize});
      Stream.ReadBuffer(Buffer, Length);
      #IFNDEF UNICODE
        S := Buffer;
      #ELSE
        S := BufferToAnsi(Buffer);
      #ENDIF
    finally
      Stream.Free;
    end;
  except
    Result := False;
  end;
end;