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// RangeCoderBit.cs
//
// Copyright (C) 2009 Bartek Jasicki based on LZMA SDK
//
// This file is part of Grubng
//
// Grubng is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
using System;
namespace Grubng
{
struct BitEncoder : IEquatable<BitEncoder>
{
public const int kNumBitModelTotalBits = 11;
public const uint kBitModelTotal = (1 << kNumBitModelTotalBits);
const int kNumMoveBits = 5;
const int kNumMoveReducingBits = 2;
public const int kNumBitPriceShiftBits = 6;
uint Prob;
public void Init() { Prob = kBitModelTotal >> 1; }
public void Encode(RangeEncoder encoder, uint symbol)
{
uint newBound = (encoder.Range >> kNumBitModelTotalBits) * Prob;
if (symbol == 0)
{
encoder.Range = newBound;
Prob += (kBitModelTotal - Prob) >> kNumMoveBits;
}
else
{
encoder.Low += newBound;
encoder.Range -= newBound;
Prob -= (Prob) >> kNumMoveBits;
}
if (encoder.Range < RangeEncoder.kTopValue)
{
encoder.Range <<= 8;
encoder.ShiftLow();
}
}
private static uint[] ProbPrices = new uint[kBitModelTotal >> kNumMoveReducingBits];
static BitEncoder()
{
int kNumBits = (kNumBitModelTotalBits - kNumMoveReducingBits);
uint start;
uint end;
for (int i = kNumBits - 1; i >= 0; i--)
{
start = (uint)1 << (kNumBits - i - 1);
end = (uint)1 << (kNumBits - i);
for (uint j = start; j < end; j++)
ProbPrices[j] = ((uint)i << kNumBitPriceShiftBits) +
(((end - j) << kNumBitPriceShiftBits) >> (kNumBits - i - 1));
}
}
public uint GetPrice(uint symbol)
{
return ProbPrices[(((Prob - symbol) ^ ((-(int)symbol))) & (kBitModelTotal - 1)) >> kNumMoveReducingBits];
}
public uint GetPrice0
{
get {return ProbPrices[Prob >> kNumMoveReducingBits];}
}
public uint GetPrice1
{
get {return ProbPrices[(kBitModelTotal - Prob) >> kNumMoveReducingBits]; }
}
/// <summary>
/// Function override standard Object.Equals(object) function
/// </summary>
/// <param name="obj">
/// A <see cref="System.Object"/> Object to compare
/// </param>
/// <returns>
/// A <see cref="System.Boolean"/> True if both objects are that same, otherwise false
/// </returns>
public override bool Equals(object obj)
{
if (obj == null)
{
return false;
}
if (GetType() != obj.GetType())
{
return false;
}
BitEncoder btencoder = (BitEncoder)obj;
return this == btencoder;
}
/// <summary>
/// Function overload function BitEncoder.Equals(object)
/// </summary>
/// <param name="right">
/// A <see cref="BitEncoder"/> value to compare
/// </param>
/// <returns>
/// A <see cref="System.Boolean"/> True if both objects are that same, otherwise false
/// </returns>
public bool Equals(BitEncoder right)
{
return this == right;
}
/// <summary>
/// Function override operator ==
/// </summary>
/// <param name="left">
/// A <see cref="BitEncoder"/> left value to compare
/// </param>
/// <param name="right">
/// A <see cref="BitEncoder"/> right value to compare
/// </param>
/// <returns>
/// A <see cref="System.Boolean"/> True if both object are that same, otherwise false
/// </returns>
public static bool operator == (BitEncoder left, BitEncoder right)
{
return left.Equals(right);
}
/// <summary>
/// Function override operator !=
/// </summary>
/// <param name="left">
/// A <see cref="BitEncoder"/> left value to compare
/// </param>
/// <param name="right">
/// A <see cref="BitEncoder"/> right value to compare
/// </param>
/// <returns>
/// A <see cref="System.Boolean"/> True if both object different, otherwise false
/// </returns>
public static bool operator != (BitEncoder left, BitEncoder right)
{
return !left.Equals(right);
}
/// <summary>
/// Function override function Object.GetHashCode();
/// </summary>
/// <returns>
/// A <see cref="System.Int32"/> hash code for current instance
/// </returns>
public override int GetHashCode()
{
int hash;
unchecked
{
hash = Prob.GetHashCode();
}
return hash;
}
}
}
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