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146 lines
3.1 KiB
C++
146 lines
3.1 KiB
C++
#ifndef IMG_HUFFMANSTREAM_H
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#define IMG_HUFFMANSTREAM_H
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#include "bitstream.h"
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#include "huffmantable.h"
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namespace IMG {
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template <class BitStream>
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class HuffmanStream {
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public:
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HuffmanStream(BitStream &bitstream, const HuffmanTable &table)
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: _bs(bitstream), _table(table), _symbolDataSize(0), _symbolData(0),
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_lonSign(0), _latSign(0) {}
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bool read(int bits, quint32 &val);
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bool readSymbol(quint32 &symbol);
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bool readNext(qint32 &lonDelta, qint32 &latDelta)
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{
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if (!(readDelta(_lonSign, lonDelta) && readDelta(_latSign, latDelta)))
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return false;
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return (lonDelta || latDelta);
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}
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bool atEnd() const
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{return _symbolDataSize + _bs.bitsAvailable() < _table.symBits();}
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bool flush() {return _bs.flush();}
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protected:
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bool sign(int &val);
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bool readDelta(int sign, qint32 &delta);
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BitStream &_bs;
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const HuffmanTable &_table;
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quint32 _symbolDataSize;
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quint32 _symbolData;
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int _lonSign, _latSign;
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};
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template <class BitStream>
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bool HuffmanStream<BitStream>::sign(int &val)
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{
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quint32 bit;
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val = 0;
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if (!_bs.read(1, bit))
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return false;
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if (bit) {
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if (!_bs.read(1, bit))
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return false;
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val = bit ? -1 : 1;
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}
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return true;
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}
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template <class BitStream>
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bool HuffmanStream<BitStream>::read(int bits, quint32 &val)
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{
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if (_symbolDataSize < (quint32)bits) {
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quint32 next;
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quint8 nextSize = qMin((quint64)(32 - _symbolDataSize),
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_bs.bitsAvailable());
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if (!_bs.read(nextSize, next))
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return false;
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_symbolData = (_symbolData << nextSize) | next;
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_symbolDataSize += nextSize;
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}
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if (_symbolDataSize < (quint32)bits)
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return false;
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val = (_symbolData << (32-_symbolDataSize)) >> (32 - bits);
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_symbolDataSize -= bits;
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return true;
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}
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template <class BitStream>
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bool HuffmanStream<BitStream>::readSymbol(quint32 &symbol)
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{
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quint8 size;
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quint32 next;
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quint8 nextSize = qMin((quint64)(32 - _symbolDataSize), _bs.bitsAvailable());
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if (!_bs.read(nextSize, next))
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return false;
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_symbolData = (_symbolData << nextSize) | next;
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_symbolDataSize += nextSize;
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symbol = _table.symbol(_symbolData << (32 - _symbolDataSize), size);
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if (size > _symbolDataSize)
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return false;
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_symbolDataSize -= size;
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return true;
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}
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template <class BitStream>
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bool HuffmanStream<BitStream>::readDelta(int sign, qint32 &delta)
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{
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quint32 symbol;
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if (!readSymbol(symbol))
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return false;
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if (symbol && !sign) {
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if (!_symbolDataSize)
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return false;
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else {
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sign = ((1U << (_symbolDataSize - 1)) & _symbolData) ? -1 : 1;
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_symbolDataSize--;
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}
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}
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delta = sign * symbol;
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return true;
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}
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class HuffmanStreamF : public HuffmanStream<BitStream4F> {
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public:
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HuffmanStreamF(BitStream4F &bitstream, const HuffmanTable &table)
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: HuffmanStream(bitstream, table) {}
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bool init(bool line);
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bool readOffset(qint32 &lonDelta, qint32 &latDelta)
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{return (readDelta(1, lonDelta) && readDelta(1, latDelta));}
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};
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class HuffmanStreamR : public HuffmanStream<BitStream4R> {
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public:
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HuffmanStreamR(BitStream4R &bitstream, const HuffmanTable &table)
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: HuffmanStream(bitstream, table) {}
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bool init();
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bool init(int lonSign, int latSign, quint32 data, quint32 dataSize);
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};
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}
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#endif // IMG_HUFFMANSTREAM_H
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