100 lines
3.1 KiB
C#
100 lines
3.1 KiB
C#
using System;
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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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/// Decompression application using static arithmetic coding.
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/// <para>Usage: java ArithmeticDecompress InputFile OutputFile</para>
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/// <para>This decompresses files generated by the "ArithmeticCompress" application.</para>
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/// </summary>
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public class ArithmeticDecompress
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{
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: public static void main(String[] args) throws java.io.IOException
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public static void Main(string[] args)
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{
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// Handle command line arguments
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if (args.Length != 2)
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{
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Console.Error.WriteLine("Usage: java ArithmeticDecompress InputFile OutputFile");
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Environment.Exit(1);
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return;
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}
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string inputFile = args[0]; // new File(args[0]);
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string outputFile = args[1]; //new File(args[1]);
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// Perform file decompression
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using( BitInputStream @in = new BitInputStream(new BufferedStream(new FileStream(inputFile, FileMode.Open, FileAccess.Read))))
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using( Stream @out = new BufferedStream(new FileStream(outputFile, FileMode.Create, FileAccess.Write) ) )
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{
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FrequencyTable freqs = readFrequencies(@in);
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decompress( freqs, @in, @out );
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}
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}
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// To allow unit testing, this method is package-private instead of private.
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: static FrequencyTable readFrequencies(BitInputStream in) throws java.io.IOException
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internal static FrequencyTable readFrequencies(BitInputStream @in)
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{
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int[] freqs = new int[257];
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for (int i = 0; i < 256; i++)
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{
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freqs[i] = readInt(@in, 32);
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}
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freqs[256] = 1; // EOF symbol
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return new SimpleFrequencyTable(freqs);
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}
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// To allow unit testing, this method is package-private instead of private.
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: static void decompress(FrequencyTable freqs, BitInputStream in, java.io.OutputStream out) throws java.io.IOException
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internal static void decompress(FrequencyTable freqs, BitInputStream @in, Stream @out)
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{
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ArithmeticDecoder dec = new ArithmeticDecoder(32, @in);
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while (true)
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{
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int symbol = dec.read(freqs);
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if (symbol == 256) // EOF symbol
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{
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break;
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}
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@out.WriteByte((byte)symbol);
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}
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}
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// Reads an unsigned integer of the given bit width from the given stream.
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//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
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//ORIGINAL LINE: private static int readInt(BitInputStream in, int numBits) throws java.io.IOException
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private static int readInt(BitInputStream @in, int numBits)
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{
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if (numBits < 0 || numBits > 32)
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{
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throw new System.ArgumentException();
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}
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int result = 0;
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for (int i = 0; i < numBits; i++)
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{
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result = (result << 1) | @in.readNoEof(); // Big endian
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}
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return result;
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}
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}
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