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// Compress/HuffmanDecoder.h
#ifndef ZIP7_INC_COMPRESS_HUFFMAN_DECODER_H
#define ZIP7_INC_COMPRESS_HUFFMAN_DECODER_H
#include "../../Common/MyTypes.h"
namespace NCompress {
namespace NHuffman {
const unsigned kNumPairLenBits = 4;
const unsigned kPairLenMask = (1 << kNumPairLenBits) - 1;
template <unsigned kNumBitsMax, UInt32 m_NumSymbols, unsigned kNumTableBits = 9>
class CDecoder
{
public:
UInt32 _limits[kNumBitsMax + 2];
UInt32 _poses[kNumBitsMax + 1];
UInt16 _lens[1 << kNumTableBits];
UInt16 _symbols[m_NumSymbols];
bool Build(const Byte *lens) throw()
{
UInt32 counts[kNumBitsMax + 1];
unsigned i;
for (i = 0; i <= kNumBitsMax; i++)
counts[i] = 0;
UInt32 sym;
for (sym = 0; sym < m_NumSymbols; sym++)
counts[lens[sym]]++;
const UInt32 kMaxValue = (UInt32)1 << kNumBitsMax;
_limits[0] = 0;
UInt32 startPos = 0;
UInt32 sum = 0;
for (i = 1; i <= kNumBitsMax; i++)
{
const UInt32 cnt = counts[i];
startPos += cnt << (kNumBitsMax - i);
if (startPos > kMaxValue)
return false;
_limits[i] = startPos;
counts[i] = sum;
_poses[i] = sum;
sum += cnt;
}
counts[0] = sum;
_poses[0] = sum;
_limits[kNumBitsMax + 1] = kMaxValue;
for (sym = 0; sym < m_NumSymbols; sym++)
{
unsigned len = lens[sym];
if (len == 0)
continue;
unsigned offset = counts[len]++;
_symbols[offset] = (UInt16)sym;
if (len <= kNumTableBits)
{
offset -= _poses[len];
UInt32 num = (UInt32)1 << (kNumTableBits - len);
UInt16 val = (UInt16)((sym << kNumPairLenBits) | len);
UInt16 *dest = _lens + (_limits[(size_t)len - 1] >> (kNumBitsMax - kNumTableBits)) + (offset << (kNumTableBits - len));
for (UInt32 k = 0; k < num; k++)
dest[k] = val;
}
}
return true;
}
bool BuildFull(const Byte *lens, UInt32 numSymbols = m_NumSymbols) throw()
{
UInt32 counts[kNumBitsMax + 1];
unsigned i;
for (i = 0; i <= kNumBitsMax; i++)
counts[i] = 0;
UInt32 sym;
for (sym = 0; sym < numSymbols; sym++)
counts[lens[sym]]++;
const UInt32 kMaxValue = (UInt32)1 << kNumBitsMax;
_limits[0] = 0;
UInt32 startPos = 0;
UInt32 sum = 0;
for (i = 1; i <= kNumBitsMax; i++)
{
const UInt32 cnt = counts[i];
startPos += cnt << (kNumBitsMax - i);
if (startPos > kMaxValue)
return false;
_limits[i] = startPos;
counts[i] = sum;
_poses[i] = sum;
sum += cnt;
}
counts[0] = sum;
_poses[0] = sum;
_limits[kNumBitsMax + 1] = kMaxValue;
for (sym = 0; sym < numSymbols; sym++)
{
unsigned len = lens[sym];
if (len == 0)
continue;
unsigned offset = counts[len]++;
_symbols[offset] = (UInt16)sym;
if (len <= kNumTableBits)
{
offset -= _poses[len];
UInt32 num = (UInt32)1 << (kNumTableBits - len);
UInt16 val = (UInt16)((sym << kNumPairLenBits) | len);
UInt16 *dest = _lens + (_limits[(size_t)len - 1] >> (kNumBitsMax - kNumTableBits)) + (offset << (kNumTableBits - len));
for (UInt32 k = 0; k < num; k++)
dest[k] = val;
}
}
return startPos == kMaxValue;
}
template <class TBitDecoder>
Z7_FORCE_INLINE
UInt32 Decode(TBitDecoder *bitStream) const
{
UInt32 val = bitStream->GetValue(kNumBitsMax);
if (val < _limits[kNumTableBits])
{
UInt32 pair = _lens[val >> (kNumBitsMax - kNumTableBits)];
bitStream->MovePos((unsigned)(pair & kPairLenMask));
return pair >> kNumPairLenBits;
}
unsigned numBits;
for (numBits = kNumTableBits + 1; val >= _limits[numBits]; numBits++);
if (numBits > kNumBitsMax)
return 0xFFFFFFFF;
bitStream->MovePos(numBits);
UInt32 index = _poses[numBits] + ((val - _limits[(size_t)numBits - 1]) >> (kNumBitsMax - numBits));
return _symbols[index];
}
template <class TBitDecoder>
Z7_FORCE_INLINE
UInt32 DecodeFull(TBitDecoder *bitStream) const
{
UInt32 val = bitStream->GetValue(kNumBitsMax);
if (val < _limits[kNumTableBits])
{
UInt32 pair = _lens[val >> (kNumBitsMax - kNumTableBits)];
bitStream->MovePos((unsigned)(pair & kPairLenMask));
return pair >> kNumPairLenBits;
}
unsigned numBits;
for (numBits = kNumTableBits + 1; val >= _limits[numBits]; numBits++);
bitStream->MovePos(numBits);
UInt32 index = _poses[numBits] + ((val - _limits[(size_t)numBits - 1]) >> (kNumBitsMax - numBits));
return _symbols[index];
}
};
template <UInt32 m_NumSymbols>
class CDecoder7b
{
Byte _lens[1 << 7];
public:
bool Build(const Byte *lens) throw()
{
const unsigned kNumBitsMax = 7;
UInt32 counts[kNumBitsMax + 1];
UInt32 _poses[kNumBitsMax + 1];
UInt32 _limits[kNumBitsMax + 1];
unsigned i;
for (i = 0; i <= kNumBitsMax; i++)
counts[i] = 0;
UInt32 sym;
for (sym = 0; sym < m_NumSymbols; sym++)
counts[lens[sym]]++;
const UInt32 kMaxValue = (UInt32)1 << kNumBitsMax;
_limits[0] = 0;
UInt32 startPos = 0;
UInt32 sum = 0;
for (i = 1; i <= kNumBitsMax; i++)
{
const UInt32 cnt = counts[i];
startPos += cnt << (kNumBitsMax - i);
if (startPos > kMaxValue)
return false;
_limits[i] = startPos;
counts[i] = sum;
_poses[i] = sum;
sum += cnt;
}
counts[0] = sum;
_poses[0] = sum;
for (sym = 0; sym < m_NumSymbols; sym++)
{
unsigned len = lens[sym];
if (len == 0)
continue;
unsigned offset = counts[len]++;
{
offset -= _poses[len];
UInt32 num = (UInt32)1 << (kNumBitsMax - len);
Byte val = (Byte)((sym << 3) | len);
Byte *dest = _lens + (_limits[(size_t)len - 1]) + (offset << (kNumBitsMax - len));
for (UInt32 k = 0; k < num; k++)
dest[k] = val;
}
}
{
UInt32 limit = _limits[kNumBitsMax];
UInt32 num = ((UInt32)1 << kNumBitsMax) - limit;
Byte *dest = _lens + limit;
for (UInt32 k = 0; k < num; k++)
dest[k] = (Byte)(0x1F << 3);
}
return true;
}
template <class TBitDecoder>
UInt32 Decode(TBitDecoder *bitStream) const
{
UInt32 val = bitStream->GetValue(7);
UInt32 pair = _lens[val];
bitStream->MovePos((unsigned)(pair & 0x7));
return pair >> 3;
}
};
}}
#endif
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