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https://github.com/tumic0/GPXSee.git
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102 lines
2.3 KiB
C++
102 lines
2.3 KiB
C++
#include "common/garmin.h"
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#include "huffmantable.h"
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using namespace Garmin;
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using namespace IMG;
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static inline quint32 readVUint32(const quint8 *buffer, quint32 bytes)
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{
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quint32 val = 0;
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for (quint32 i = 0; i < bytes; i++)
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val |= ((quint32)*(buffer + i)) << (i * 8);
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return val;
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}
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bool HuffmanTable::load(const RGNFile *rgn, SubFile::Handle &rgnHdl)
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{
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if (!_buffer.load(rgn, rgnHdl))
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return false;
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_aclBits = (quint8)_buffer.at(0) & 0x0F;
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_huffman = (quint8)_buffer.at(0) & 0x10;
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_symBits = (quint8)_buffer.at(1);
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_symBytes = bs(_symBits);
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_bsrchEntries = (quint8)_buffer.at(2);
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_symbolBits = (quint8)_buffer.at(3);
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_symbolBytes = bs(_symbolBits);
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_aclEntryBytes = _symbolBytes + 1;
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_indexBytes = vs(_buffer.at(4));
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_bsrchEntryBytes = _symBytes + _indexBytes + 1;
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_bsrchTable = (const quint8*)(_buffer.constData()) + 4 + _indexBytes;
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_aclTable = _bsrchTable + _bsrchEntryBytes * _bsrchEntries;
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_huffmanTable = _aclTable + (_aclEntryBytes << _aclBits);
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return (_symBits <= 32 && _symbolBits <= 32);
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}
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quint32 HuffmanTable::symbol(quint32 data, quint8 &size) const
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{
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quint32 lo, hi;
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const quint8 *tp;
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if (!_aclBits) {
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hi = _bsrchEntries - 1;
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lo = 0;
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} else {
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quint32 offset = _aclEntryBytes * (data >> (32 - _aclBits));
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tp = _aclTable + offset;
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if (*tp & 1) {
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size = *tp >> 1;
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return readVUint32(tp + 1, _symbolBytes);;
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}
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lo = *tp >> 1;
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hi = *(tp + 1);
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}
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tp = _bsrchTable + (lo * _bsrchEntryBytes);
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data >>= 32 - _symBits;
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while (lo < hi) {
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const quint8 *prev = tp;
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quint32 m = (lo + 1 + hi) >> 1;
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tp = _bsrchTable + (m * _bsrchEntryBytes);
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quint32 nd = readVUint32(tp, _symBytes);
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if (data < nd) {
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tp = prev;
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hi = m - 1;
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} else if (data > nd) {
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lo = m;
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} else {
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lo = m;
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hi = m;
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}
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}
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quint32 i = readVUint32(tp, _symBytes);
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tp = tp + _symBytes;
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size = *tp;
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if (!_huffman)
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return readVUint32(tp + 1, _symbolBytes);
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else {
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quint32 bi = readVUint32(tp + 1, _indexBytes);
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quint32 ci = (data - i) >> (_symBits - size);
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quint32 si = (ci + bi) * _symbolBits;
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quint32 sbi = si & 7;
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quint32 shift = 8 - sbi;
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tp = _huffmanTable + (si >> 3);
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if (shift < _symbolBits) {
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quint32 val = readVUint32(tp + 1, bs(_symbolBits - shift));
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return (val << shift) | (*tp >> sbi);
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} else
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return (*tp >> sbi);
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}
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}
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