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// Compress/RangeCoder.h
// 2013-01-10 : Igor Pavlov : Public domain
#ifndef __COMPRESS_RANGE_CODER_H
#define __COMPRESS_RANGE_CODER_H
#include "../Common/InBuffer.h"
#include "../Common/OutBuffer.h"
namespace NCompress {
namespace NRangeCoder {
const unsigned kNumTopBits = 24;
const UInt32 kTopValue = (1 << kNumTopBits);
class CEncoder
{
UInt32 _cacheSize;
Byte _cache;
public:
UInt64 Low;
UInt32 Range;
COutBuffer Stream;
bool Create(UInt32 bufSize) { return Stream.Create(bufSize); }
void SetStream(ISequentialOutStream *stream) { Stream.SetStream(stream); }
void Init()
{
Stream.Init();
Low = 0;
Range = 0xFFFFFFFF;
_cacheSize = 1;
_cache = 0;
}
void FlushData()
{
// Low += 1;
for (int i = 0; i < 5; i++)
ShiftLow();
}
HRESULT FlushStream() { return Stream.Flush(); }
void Encode(UInt32 start, UInt32 size, UInt32 total)
{
Low += start * (Range /= total);
Range *= size;
while (Range < kTopValue)
{
Range <<= 8;
ShiftLow();
}
}
void ShiftLow()
{
if ((UInt32)Low < (UInt32)0xFF000000 || (unsigned)(Low >> 32) != 0)
{
Byte temp = _cache;
do
{
Stream.WriteByte((Byte)(temp + (Byte)(Low >> 32)));
temp = 0xFF;
}
while (--_cacheSize != 0);
_cache = (Byte)((UInt32)Low >> 24);
}
_cacheSize++;
Low = (UInt32)Low << 8;
}
void EncodeDirectBits(UInt32 value, int numBits)
{
for (numBits--; numBits >= 0; numBits--)
{
Range >>= 1;
Low += Range & (0 - ((value >> numBits) & 1));
if (Range < kTopValue)
{
Range <<= 8;
ShiftLow();
}
}
}
void EncodeBit(UInt32 size0, UInt32 numTotalBits, UInt32 symbol)
{
UInt32 newBound = (Range >> numTotalBits) * size0;
if (symbol == 0)
Range = newBound;
else
{
Low += newBound;
Range -= newBound;
}
while (Range < kTopValue)
{
Range <<= 8;
ShiftLow();
}
}
UInt64 GetProcessedSize() { return Stream.GetProcessedSize() + _cacheSize + 4; }
};
class CDecoder
{
public:
CInBuffer Stream;
UInt32 Range;
UInt32 Code;
bool Create(UInt32 bufSize) { return Stream.Create(bufSize); }
void Normalize()
{
while (Range < kTopValue)
{
Code = (Code << 8) | Stream.ReadByte();
Range <<= 8;
}
}
void SetStream(ISequentialInStream *stream) { Stream.SetStream(stream); }
void Init()
{
Stream.Init();
Code = 0;
Range = 0xFFFFFFFF;
for (int i = 0; i < 5; i++)
Code = (Code << 8) | Stream.ReadByte();
}
UInt32 GetThreshold(UInt32 total)
{
return (Code) / (Range /= total);
}
void Decode(UInt32 start, UInt32 size)
{
Code -= start * Range;
Range *= size;
Normalize();
}
UInt32 DecodeDirectBits(int numTotalBits)
{
UInt32 range = Range;
UInt32 code = Code;
UInt32 result = 0;
for (int i = numTotalBits; i != 0; i--)
{
range >>= 1;
/*
result <<= 1;
if (code >= range)
{
code -= range;
result |= 1;
}
*/
UInt32 t = (code - range) >> 31;
code -= range & (t - 1);
result = (result << 1) | (1 - t);
if (range < kTopValue)
{
code = (code << 8) | Stream.ReadByte();
range <<= 8;
}
}
Range = range;
Code = code;
return result;
}
UInt32 DecodeBit(UInt32 size0, UInt32 numTotalBits)
{
UInt32 newBound = (Range >> numTotalBits) * size0;
UInt32 symbol;
if (Code < newBound)
{
symbol = 0;
Range = newBound;
}
else
{
symbol = 1;
Code -= newBound;
Range -= newBound;
}
Normalize();
return symbol;
}
UInt64 GetProcessedSize() { return Stream.GetProcessedSize(); }
};
}}
#endif
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