xbt_assert((index >= 0 && index <= FILE_PIECES), "Wrong piece.");
xbt_assert((block_index >= 0 && block_index <= PIECES_BLOCKS), "Wrong block : %d.", block_index);
for (int i = block_index; i < (block_index + block_length); i++) {
xbt_assert((index >= 0 && index <= FILE_PIECES), "Wrong piece.");
xbt_assert((block_index >= 0 && block_index <= PIECES_BLOCKS), "Wrong block : %d.", block_index);
for (int i = block_index; i < (block_index + block_length); i++) {