/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for Additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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/* ================================================================
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* About NPOI
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* Author: Tony Qu
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* Author's email: tonyqus (at) gmail.com
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* Author's Blog: tonyqus.wordpress.com.cn (wp.tonyqus.cn)
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* HomePage: http://www.codeplex.com/npoi
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* Contributors:
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*
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* ==============================================================*/
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using System;
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using System.Collections.Generic;
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using System.IO;
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using HH.WMS.Utils.NPOI.POIFS.Common;
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using HH.WMS.Utils.NPOI.POIFS.FileSystem;
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using HH.WMS.Utils.NPOI.POIFS.NIO;
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using HH.WMS.Utils.NPOI.Util;
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namespace HH.WMS.Utils.NPOI.POIFS.Storage
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{
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/// <summary>
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/// This class manages and creates the Block Allocation Table, which is
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/// basically a set of linked lists of block indices.
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/// Each block of the filesystem has an index. The first block, the
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/// header, is skipped; the first block after the header is index 0,
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/// the next is index 1, and so on.
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/// A block's index is also its index into the Block Allocation
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/// Table. The entry that it finds in the Block Allocation Table is the
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/// index of the next block in the linked list of blocks making up a
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/// file, or it is set to -2: end of list.
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/// *
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/// @author Marc Johnson (mjohnson at apache dot org)
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/// </summary>
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public class BlockAllocationTableWriter : BlockWritable, BATManaged
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{
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private List<int> _entries;
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private BATBlock[] _blocks;
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private int _start_block;
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private POIFSBigBlockSize _bigBlockSize;
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private static int _default_size = 128;
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/// <summary>
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/// Initializes a new instance of the <see cref="BlockAllocationTableWriter"/> class.
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/// </summary>
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public BlockAllocationTableWriter(POIFSBigBlockSize bigBlockSize)
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{
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_start_block = POIFSConstants.END_OF_CHAIN;
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_entries = new List<int>(_default_size);
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_blocks = new BATBlock[ 0 ];
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_bigBlockSize = bigBlockSize;
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}
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/// <summary>
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/// Create the BATBlocks we need
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/// </summary>
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/// <returns>start block index of BAT blocks</returns>
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public int CreateBlocks()
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{
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int xbat_blocks = 0;
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int bat_blocks = 0;
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while (true)
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{
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int calculated_bat_blocks =
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BATBlock.CalculateStorageRequirements(_bigBlockSize,
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bat_blocks
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+ xbat_blocks
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+ _entries.Count);
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int calculated_xbat_blocks =
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HeaderBlockWriter.CalculateXBATStorageRequirements(_bigBlockSize,calculated_bat_blocks);
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if ((bat_blocks == calculated_bat_blocks)
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&& (xbat_blocks == calculated_xbat_blocks))
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{
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// stable ... we're OK
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break;
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}
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else
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{
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bat_blocks = calculated_bat_blocks;
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xbat_blocks = calculated_xbat_blocks;
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}
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}
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int startBlock = AllocateSpace(bat_blocks);
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AllocateSpace(xbat_blocks);
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SimpleCreateBlocks();
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return startBlock;
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}
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/// <summary>
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/// Allocate space for a block of indices
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/// </summary>
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/// <param name="blockCount">the number of blocks to allocate space for</param>
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/// <returns>the starting index of the blocks</returns>
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public int AllocateSpace(int blockCount)
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{
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int startBlock = _entries.Count;
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if (blockCount > 0)
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{
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int limit = blockCount - 1;
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int index = startBlock + 1;
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for (int k = 0; k < limit; k++)
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{
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_entries.Add(index++);
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}
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_entries.Add(POIFSConstants.END_OF_CHAIN);
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}
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return startBlock;
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}
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/// <summary>
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/// Sets the start block for this instance
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/// </summary>
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/// <value>
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/// index into the array of BigBlock instances making up the the filesystem
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/// </value>
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public int StartBlock
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{
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get { return _start_block; }
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set { _start_block = value; }
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}
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/// <summary>
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/// create the BATBlocks
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/// </summary>
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internal void SimpleCreateBlocks()
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{
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_blocks = BATBlock.CreateBATBlocks(_bigBlockSize, _entries.ToArray());
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}
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/// <summary>
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/// Write the storage to an OutputStream
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/// </summary>
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/// <param name="stream">the OutputStream to which the stored data should be written</param>
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public void WriteBlocks(Stream stream)
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{
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for (int j = 0; j < _blocks.Length; j++)
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{
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_blocks[ j ].WriteBlocks(stream);
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}
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}
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//public static void WriteBlock(BATBlock bat, byte[] block)
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public static void WriteBlock(BATBlock bat, ByteBuffer block)
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{
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bat.WriteData(block);
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}
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/// <summary>
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/// Gets the number of BigBlock's this instance uses
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/// </summary>
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/// <value>count of BigBlock instances</value>
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public int CountBlocks
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{
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get { return _blocks.Length; }
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}
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}
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}
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