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// LzmaBase.cs
namespace SevenZip.Compression.LZMA
{
internal abstract class Base
{
public const uint kNumRepDistances = 4;
public const uint kNumStates = 12;
// static byte []kLiteralNextStates = {0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 4, 5};
// static byte []kMatchNextStates = {7, 7, 7, 7, 7, 7, 7, 10, 10, 10, 10, 10};
// static byte []kRepNextStates = {8, 8, 8, 8, 8, 8, 8, 11, 11, 11, 11, 11};
// static byte []kShortRepNextStates = {9, 9, 9, 9, 9, 9, 9, 11, 11, 11, 11, 11};
public struct State
{
public uint Index;
public void Init() { Index = 0; }
public void UpdateChar()
{
if (Index < 4) Index = 0;
else if (Index < 10) Index -= 3;
else Index -= 6;
}
public void UpdateMatch() { Index = (uint)(Index < 7 ? 7 : 10); }
public void UpdateRep() { Index = (uint)(Index < 7 ? 8 : 11); }
public void UpdateShortRep() { Index = (uint)(Index < 7 ? 9 : 11); }
public bool IsCharState() { return Index < 7; }
}
public const int kNumPosSlotBits = 6;
public const int kDicLogSizeMin = 0;
// public const int kDicLogSizeMax = 30;
// public const uint kDistTableSizeMax = kDicLogSizeMax * 2;
public const int kNumLenToPosStatesBits = 2; // it's for speed optimization
public const uint kNumLenToPosStates = 1 << kNumLenToPosStatesBits;
public const uint kMatchMinLen = 2;
public static uint GetLenToPosState(uint len)
{
len -= kMatchMinLen;
if (len < kNumLenToPosStates)
return len;
return (uint)(kNumLenToPosStates - 1);
}
public const int kNumAlignBits = 4;
public const uint kAlignTableSize = 1 << kNumAlignBits;
public const uint kAlignMask = (kAlignTableSize - 1);
public const uint kStartPosModelIndex = 4;
public const uint kEndPosModelIndex = 14;
public const uint kNumPosModels = kEndPosModelIndex - kStartPosModelIndex;
public const uint kNumFullDistances = 1 << ((int)kEndPosModelIndex / 2);
public const uint kNumLitPosStatesBitsEncodingMax = 4;
public const uint kNumLitContextBitsMax = 8;
public const int kNumPosStatesBitsMax = 4;
public const uint kNumPosStatesMax = (1 << kNumPosStatesBitsMax);
public const int kNumPosStatesBitsEncodingMax = 4;
public const uint kNumPosStatesEncodingMax = (1 << kNumPosStatesBitsEncodingMax);
public const int kNumLowLenBits = 3;
public const int kNumMidLenBits = 3;
public const int kNumHighLenBits = 8;
public const uint kNumLowLenSymbols = 1 << kNumLowLenBits;
public const uint kNumMidLenSymbols = 1 << kNumMidLenBits;
public const uint kNumLenSymbols = kNumLowLenSymbols + kNumMidLenSymbols +
(1 << kNumHighLenBits);
public const uint kMatchMaxLen = kMatchMinLen + kNumLenSymbols - 1;
}
}
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