94 lines
2.8 KiB
C#
94 lines
2.8 KiB
C#
//
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// Copyright (c) 2008-2011, Kenneth Bell
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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using System.IO;
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namespace DiscUtils.Compression
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{
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/// <summary>
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/// Converts a byte stream into a bit stream.
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/// </summary>
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internal class BigEndianBitStream : BitStream
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{
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private uint _buffer;
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private int _bufferAvailable;
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private readonly Stream _byteStream;
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private readonly byte[] _readBuffer = new byte[2];
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public BigEndianBitStream(Stream byteStream)
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{
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_byteStream = byteStream;
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}
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public override int MaxReadAhead
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{
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get { return 16; }
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}
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public override uint Read(int count)
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{
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if (count > 16)
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{
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uint result = Read(16) << (count - 16);
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return result | Read(count - 16);
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}
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EnsureBufferFilled();
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_bufferAvailable -= count;
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uint mask = (uint)((1 << count) - 1);
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return (_buffer >> _bufferAvailable) & mask;
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}
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public override uint Peek(int count)
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{
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EnsureBufferFilled();
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uint mask = (uint)((1 << count) - 1);
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return (_buffer >> (_bufferAvailable - count)) & mask;
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}
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public override void Consume(int count)
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{
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EnsureBufferFilled();
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_bufferAvailable -= count;
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}
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private void EnsureBufferFilled()
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{
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if (_bufferAvailable < 16)
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{
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_readBuffer[0] = 0;
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_readBuffer[1] = 0;
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_byteStream.Read(_readBuffer, 0, 2);
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_buffer = _buffer << 16 | (uint)(_readBuffer[0] << 8) | _readBuffer[1];
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_bufferAvailable += 16;
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}
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}
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}
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} |