269 lines
6.0 KiB
C#
269 lines
6.0 KiB
C#
namespace ICSharpCode.SharpZipLib.Zip.Compression
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{
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/// <summary>
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/// This class is general purpose class for writing data to a buffer.
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///
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/// It allows you to write bits as well as bytes
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/// Based on DeflaterPending.java
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///
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/// author of the original java version : Jochen Hoenicke
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/// </summary>
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public class PendingBuffer
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{
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#region Instance Fields
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/// <summary>
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/// Internal work buffer
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/// </summary>
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private readonly byte[] buffer;
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private int start;
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private int end;
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private uint bits;
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private int bitCount;
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#endregion Instance Fields
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#region Constructors
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/// <summary>
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/// construct instance using default buffer size of 4096
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/// </summary>
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public PendingBuffer() : this(4096)
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{
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}
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/// <summary>
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/// construct instance using specified buffer size
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/// </summary>
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/// <param name="bufferSize">
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/// size to use for internal buffer
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/// </param>
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public PendingBuffer(int bufferSize)
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{
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buffer = new byte[bufferSize];
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}
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#endregion Constructors
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/// <summary>
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/// Clear internal state/buffers
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/// </summary>
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public void Reset()
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{
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start = end = bitCount = 0;
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}
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/// <summary>
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/// Write a byte to buffer
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/// </summary>
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/// <param name="value">
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/// The value to write
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/// </param>
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public void WriteByte(int value)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer[end++] = unchecked((byte)value);
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}
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/// <summary>
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/// Write a short value to buffer LSB first
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/// </summary>
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/// <param name="value">
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/// The value to write.
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/// </param>
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public void WriteShort(int value)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer[end++] = unchecked((byte)value);
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buffer[end++] = unchecked((byte)(value >> 8));
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}
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/// <summary>
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/// write an integer LSB first
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/// </summary>
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/// <param name="value">The value to write.</param>
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public void WriteInt(int value)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer[end++] = unchecked((byte)value);
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buffer[end++] = unchecked((byte)(value >> 8));
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buffer[end++] = unchecked((byte)(value >> 16));
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buffer[end++] = unchecked((byte)(value >> 24));
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}
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/// <summary>
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/// Write a block of data to buffer
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/// </summary>
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/// <param name="block">data to write</param>
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/// <param name="offset">offset of first byte to write</param>
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/// <param name="length">number of bytes to write</param>
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public void WriteBlock(byte[] block, int offset, int length)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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System.Array.Copy(block, offset, buffer, end, length);
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end += length;
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}
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/// <summary>
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/// The number of bits written to the buffer
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/// </summary>
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public int BitCount
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{
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get
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{
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return bitCount;
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}
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}
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/// <summary>
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/// Align internal buffer on a byte boundary
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/// </summary>
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public void AlignToByte()
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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if (bitCount > 0)
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{
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buffer[end++] = unchecked((byte)bits);
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if (bitCount > 8)
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{
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buffer[end++] = unchecked((byte)(bits >> 8));
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}
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}
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bits = 0;
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bitCount = 0;
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}
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/// <summary>
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/// Write bits to internal buffer
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/// </summary>
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/// <param name="b">source of bits</param>
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/// <param name="count">number of bits to write</param>
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public void WriteBits(int b, int count)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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// if (DeflaterConstants.DEBUGGING) {
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// //Console.WriteLine("writeBits("+b+","+count+")");
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// }
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#endif
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bits |= (uint)(b << bitCount);
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bitCount += count;
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if (bitCount >= 16)
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{
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buffer[end++] = unchecked((byte)bits);
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buffer[end++] = unchecked((byte)(bits >> 8));
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bits >>= 16;
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bitCount -= 16;
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}
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}
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/// <summary>
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/// Write a short value to internal buffer most significant byte first
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/// </summary>
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/// <param name="s">value to write</param>
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public void WriteShortMSB(int s)
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{
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#if DebugDeflation
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if (DeflaterConstants.DEBUGGING && (start != 0) )
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{
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throw new SharpZipBaseException("Debug check: start != 0");
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}
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#endif
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buffer[end++] = unchecked((byte)(s >> 8));
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buffer[end++] = unchecked((byte)s);
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}
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/// <summary>
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/// Indicates if buffer has been flushed
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/// </summary>
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public bool IsFlushed
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{
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get
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{
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return end == 0;
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}
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}
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/// <summary>
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/// Flushes the pending buffer into the given output array. If the
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/// output array is to small, only a partial flush is done.
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/// </summary>
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/// <param name="output">The output array.</param>
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/// <param name="offset">The offset into output array.</param>
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/// <param name="length">The maximum number of bytes to store.</param>
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/// <returns>The number of bytes flushed.</returns>
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public int Flush(byte[] output, int offset, int length)
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{
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if (bitCount >= 8)
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{
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buffer[end++] = unchecked((byte)bits);
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bits >>= 8;
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bitCount -= 8;
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}
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if (length > end - start)
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{
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length = end - start;
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System.Array.Copy(buffer, start, output, offset, length);
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start = 0;
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end = 0;
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}
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else
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{
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System.Array.Copy(buffer, start, output, offset, length);
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start += length;
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}
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return length;
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}
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/// <summary>
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/// Convert internal buffer to byte array.
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/// Buffer is empty on completion
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/// </summary>
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/// <returns>
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/// The internal buffer contents converted to a byte array.
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/// </returns>
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public byte[] ToByteArray()
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{
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AlignToByte();
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byte[] result = new byte[end - start];
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System.Array.Copy(buffer, start, result, 0, result.Length);
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start = 0;
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end = 0;
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return result;
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}
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}
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}
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