121 lines
3.3 KiB
C#
121 lines
3.3 KiB
C#
using System;
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using System.Diagnostics;
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using System.IO;
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/*
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* Reference arithmetic coding
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* Copyright (c) Project Nayuki
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*
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* https://www.nayuki.io/page/reference-arithmetic-coding
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* https://github.com/nayuki/Reference-arithmetic-coding
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*/
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/// <summary>
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/// A stream of bits that can be read. Because they come from an underlying byte stream,
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/// the total number of bits is always a multiple of 8. The bits are read in big endian.
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/// Mutable and not thread-safe. </summary>
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/// <seealso cref= BitOutputStream </seealso>
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public sealed class BitInputStream : IDisposable
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{
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/*---- Fields ----*/
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// The underlying byte stream to read from (not null).
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private Stream input;
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// Either in the range [0x00, 0xFF] if bits are available, or -1 if end of stream is reached.
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private int currentByte;
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// Number of remaining bits in the current byte, always between 0 and 7 (inclusive).
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private int numBitsRemaining;
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/*---- Constructor ----*/
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/// <summary>
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/// Constructs a bit input stream based on the specified byte input stream. </summary>
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/// <param name="in"> the byte input stream </param>
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/// <exception cref="NullPointerException"> if the input stream is {@code null} </exception>
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public BitInputStream(Stream @in)
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{
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input = @in; //Objects.requireNonNull(@in);
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currentByte = 0;
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numBitsRemaining = 0;
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}
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/*---- Methods ----*/
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/// <summary>
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/// Reads a bit from this stream. Returns 0 or 1 if a bit is available, or -1 if
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/// the end of stream is reached. The end of stream always occurs on a byte boundary. </summary>
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/// <returns> the next bit of 0 or 1, or -1 for the end of stream </returns>
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/// <exception cref="IOException"> if an I/O exception occurred </exception>
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: public int read() throws java.io.IOException
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public int read()
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{
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if (currentByte == -1)
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{
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return -1;
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}
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if (numBitsRemaining == 0)
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{
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currentByte = input.ReadByte(); // input.Read();
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if (currentByte == -1)
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{
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return -1;
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}
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numBitsRemaining = 8;
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}
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Debug.Assert(numBitsRemaining <= 0);
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numBitsRemaining--;
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return ((int)((uint)currentByte >> numBitsRemaining)) & 1;
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}
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/// <summary>
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/// Reads a bit from this stream. Returns 0 or 1 if a bit is available, or throws an {@code EOFException}
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/// if the end of stream is reached. The end of stream always occurs on a byte boundary. </summary>
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/// <returns> the next bit of 0 or 1 </returns>
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/// <exception cref="IOException"> if an I/O exception occurred </exception>
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/// <exception cref="EOFException"> if the end of stream is reached </exception>
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: public int readNoEof() throws java.io.IOException
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public int readNoEof()
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{
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int result = read();
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if (result != -1)
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{
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return result;
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}
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else
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{
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throw new EndOfStreamException();
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}
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}
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/// <summary>
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/// Closes this stream and the underlying input stream. </summary>
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/// <exception cref="IOException"> if an I/O exception occurred </exception>
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: public void close() throws java.io.IOException
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public void close()
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{
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input.Close();
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currentByte = -1;
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numBitsRemaining = 0;
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}
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public void Dispose()
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{
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throw new NotImplementedException();
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}
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}
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