loci.poi.poifs.storage

Class BlockAllocationTableWriter

java.lang.Object

loci.poi.poifs.storage.BlockAllocationTableWriter

All Implemented Interfaces:

BATManaged, BlockWritable

public class BlockAllocationTableWriter
extends Object
implements BlockWritable, BATManaged

This class manages and creates the Block Allocation Table, which is basically a set of linked lists of block indices.

Each block of the filesystem has an index. The first block, the header, is skipped; the first block after the header is index 0, the next is index 1, and so on.

A block's index is also its index into the Block Allocation Table. The entry that it finds in the Block Allocation Table is the index of the next block in the linked list of blocks making up a file, or it is set to -2: end of list.

Author:

Marc Johnson (mjohnson at apache dot org)

Field Summary

Fields

Modifier and Type	Field and Description
private BATBlock[]	_blocks
private IntList	_entries
private int	_start_block

Constructor Summary

Constructors

Constructor and Description
BlockAllocationTableWriter() create a BlockAllocationTableWriter

Method Summary

Methods

Modifier and Type	Method and Description
int	allocateSpace(int blockCount) Allocate space for a block of indices
int	countBlocks() Return the number of BigBlock's this instance uses
int	createBlocks(int size) Create the BATBlocks we need
int	getStartBlock() get the starting block
void	setStartBlock(int start_block) Set the start block for this instance
(package private) void	simpleCreateBlocks(int size) create the BATBlocks
void	writeBlocks(OutputStream stream) Write the storage to an OutputStream

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_entries

private IntList _entries

_blocks

private BATBlock[] _blocks

_start_block

private int _start_block

Constructor Detail

BlockAllocationTableWriter

public BlockAllocationTableWriter()

create a BlockAllocationTableWriter

Method Detail

createBlocks

public int createBlocks(int size)

Create the BATBlocks we need

Returns:

start block index of BAT blocks

allocateSpace

public int allocateSpace(int blockCount)

Allocate space for a block of indices

Parameters:

blockCount - the number of blocks to allocate space for

Returns:

the starting index of the blocks

getStartBlock

public int getStartBlock()

get the starting block

Returns:

the starting block index

simpleCreateBlocks

void simpleCreateBlocks(int size)

create the BATBlocks

writeBlocks

public void writeBlocks(OutputStream stream)
                 throws IOException

Write the storage to an OutputStream

Specified by:

writeBlocks in interface BlockWritable

Parameters:

stream - the OutputStream to which the stored data should be written

Throws:

IOException - on problems writing to the specified stream

countBlocks

public int countBlocks()

Return the number of BigBlock's this instance uses

Specified by:

countBlocks in interface BATManaged

Returns:

count of BigBlock instances

setStartBlock

public void setStartBlock(int start_block)

Set the start block for this instance

Specified by:

setStartBlock in interface BATManaged

Parameters:

start_block -