CRAMFS_BLK_FLAGS
first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
block_ptr &= ~CRAMFS_BLK_FLAGS;
block_start = prev_start & ~CRAMFS_BLK_FLAGS;
block_start &= ~CRAMFS_BLK_FLAGS;