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478 lines
13 KiB
478 lines
13 KiB
//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1991 - 1997.
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//
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// File: COMPRESS.HXX
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//
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// Contents: Compressor/Decompressor of data
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//
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// Classes: CCompress, CDecompress
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//
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// History: 12-Jun-91 BartoszM Created
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// 20-Jun-91 reviewed
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// 07-Aug-91 BartoszM Introduced Blocks
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// 28-May-92 KyleP Added compression
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//
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//----------------------------------------------------------------------------
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#pragma once
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#include <pageman.hxx>
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const USHORT offInvalid = 0xffff;
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const ULONG cbInitialBlock = 8192;
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//+---------------------------------------------------------------------------
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//
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// Class: CBlock
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//
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// Purpose: Block of data in sort chunk
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//
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// History: 7-Aug-91 BartoszM Created
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//
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//----------------------------------------------------------------------------
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class CBlock
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{
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public:
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CBlock() :
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_pNext(0),
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_fCompressed(FALSE),
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_cbCompressed(0),
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_cbInUse(0),
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_offFirstKey(offInvalid)
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{
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_pData = new BYTE[ cbInitialBlock ];
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}
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~CBlock() { delete [] _pData; }
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void GetFirstKey ( CKeyBuf & key );
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void CompressList();
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void Compress();
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void DeCompress();
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BYTE * Buffer() { return _pData; }
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USHORT InUse() { return _cbInUse; }
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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CBlock * _pNext;
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BYTE * _pData; // the actual data
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USHORT _fCompressed; // whether _pData is RtlCompressed
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USHORT _cbCompressed; // size when compressed
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USHORT _cbInUse; // size of actual uncompressed data in buffer
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USHORT _offFirstKey; // offset to first key in buffer
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CCompress
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//
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// Purpose: Compress data into a series of blocks
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//
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// History: 12-Jun-91 BartoszM Created
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// 13-May-92 KyleP Added compression.
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//
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// Notes: The following compression schemes are used:
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// o Prefix compressed keys
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// o 1 Byte Wid/WidCount (max 255 Wid/compressor)
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// o 1 byte/2 byte/4 byte occurrence deltas.
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//
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//----------------------------------------------------------------------------
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class CCompress
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{
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public:
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CCompress();
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~CCompress();
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CBlock * GetFirstBlock();
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void PutKey ( unsigned cb, const BYTE* buf, PROPID pid );
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void PutWid ( WORKID wid );
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void PutOcc ( OCCURRENCE occ );
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BOOL SameWid ( WORKID wid ) const
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{ return ( wid == _lastWid ); }
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BOOL SamePid ( PROPID pid ) const
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{ return ( pid == _lastKey.Pid() ); }
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inline BOOL SameKey ( unsigned cb, const BYTE * buf ) const;
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unsigned KeyBlockCount () { return _cKeyBlock; }
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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protected:
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inline BOOL KeyWillFit( unsigned cb ) const;
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inline BOOL WidAndOccCountWillFit() const;
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inline BOOL WidWillFit() const;
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inline BOOL OccWillFit( OCCURRENCE occDelta ) const;
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inline BOOL OccCountWillFit() const;
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//
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// The Internal put methods are used as the building blocks for
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// PutKey/Wid/Occ in both CCompress and COneWidCompress.
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//
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void IPutKey( unsigned cb, const BYTE * buf, PROPID pid );
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void IPutWid( WORKID wid );
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void IAllocWidCount();
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void IPutWidCount();
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void IPutOcc( OCCURRENCE occ );
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void IAllocOccCount();
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void IPutOccCount();
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void AllocNewBlock ();
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void BackPatch ( unsigned off )
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{
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_block->_offFirstKey = (WORD)off;
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_cKeyBlock++;
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}
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WORKID _lastWid;
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OCCURRENCE _lastOcc;
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// pointers for back-patching the counts
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BYTE * _pWidCount;
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BYTE * _pOccCount;
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unsigned _widCount;
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unsigned _occCount;
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CBlock * _block; // current block
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unsigned _cKeyBlock; // count of blocks with keys
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BYTE* _buf; // current buffer to write to
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BYTE* _cur; // current position in buffer
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//
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// For prefix compression.
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//
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CKeyBuf _lastKey;
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};
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//+---------------------------------------------------------------------------
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//
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// Class: COneWidCompress
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//
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// Purpose: Compress data for single workid into a series of blocks.
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//
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// History: 26-May-92 KyleP Created
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//
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// Notes: In addition to the compression schemes used in CCompress
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// no WorkId or WorkId count is stored at all.
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//
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//----------------------------------------------------------------------------
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class COneWidCompress : public CCompress
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{
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public:
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void PutKey ( unsigned cb, const BYTE* buf, PROPID pid );
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#if CIDBG == 1
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void PutWid ( WORKID wid );
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#endif // CIDBG == 1
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void PutOcc ( OCCURRENCE occ );
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CDecompress
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//
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// Purpose: Decompress data
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//
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// History: 12-Jun-91 BartoszM Created
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// 28-May-92 KyleP Added compression
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//
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// Notes: CDecompress uncompresses buffers compressed with CCompress.
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//
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//----------------------------------------------------------------------------
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class CDecompress
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{
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public:
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inline const CKeyBuf* GetKey() const;
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inline WORKID WorkId() const;
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inline OCCURRENCE Occurrence() const;
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//
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// Init and GetNext* will be over-ridden in COneWidDecompress.
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//
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void Init (CBlock* block );
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const CKeyBuf* GetNextKey();
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WORKID NextWorkId();
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OCCURRENCE NextOccurrence();
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ULONG WorkIdCount() { return _widCount; }
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ULONG OccurrenceCount() { return _occCount; }
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void RatioFinished ( ULONG& denom, ULONG& num );
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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protected:
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//
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// The Load methods are used as building blocks for both CDecompress
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// and COneWidDecompress.
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//
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BOOL LoadNextBlock ();
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void LoadKey();
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void LoadWidCount();
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void LoadWid();
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void LoadOccCount();
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void LoadOcc();
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BOOL KeyExists() const
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{ return _curKey.Count() != 0; }
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BOOL EndBlock() const
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{ return ( (unsigned)(_cur - _buf) >= _cbInUse ); }
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CBlock* _block; // current block
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unsigned _cbInUse; // actual number of bytes in buffer
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const BYTE* _buf; // buffer to read from
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const BYTE* _cur; // current position within buffer
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BYTE _widCount; // work id count
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unsigned _occCount; // occurrence count
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unsigned _widCountLeft; // work ids left
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unsigned _occCountLeft; // occurrences left
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CKeyBuf _curKey; // Key under the cursor
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WORKID _curWid; // WorkId under the cursor
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OCCURRENCE _curOcc; // Occurrence under the cursor
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};
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//+---------------------------------------------------------------------------
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//
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// Class: COneWidDecompress
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//
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// Purpose: Decompress data
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//
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// History: 28-May-92 KyleP Created
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//
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// Notes: COneWidDecompress uncompresses buffers compressed
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// with COneWidCompress.
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//
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//----------------------------------------------------------------------------
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class COneWidDecompress : public CDecompress
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{
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public:
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void Init( CBlock* block );
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const CKeyBuf* GetNextKey();
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WORKID NextWorkId();
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OCCURRENCE NextOccurrence();
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};
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//+---------------------------------------------------------------------------
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//
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// Member: CCompress::SameKey, public
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//
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// Synopsis: compare argument with last key
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//
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// Arguments: [cb] - size of key
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// [buf] - key buffer
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//
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// History: 12-Jun-91 BartoszM Created
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//
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//----------------------------------------------------------------------------
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inline BOOL CCompress::SameKey ( unsigned cb, const BYTE * buf ) const
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{
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if ( cb == _lastKey.Count() )
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return ( memcmp ( buf, _lastKey.GetBuf(), cb ) == 0 );
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else
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return FALSE;
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CCompress::KeyWillFit, private
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//
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// Synopsis: check if the key will fit into current buffer
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//
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// Arguments: [cb] -- byte size of the key suffix
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//
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// History: 07-Aug-91 BartoszM Created
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// 28-May-92 KyleP Adjusted for compression
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//
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//----------------------------------------------------------------------------
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inline BOOL CCompress::KeyWillFit ( unsigned cb ) const
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{
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// This is an absolutely worst-case estimate. Most keys will be smaller.
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// Note: This also allocates room for the wid count, which is only needed
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// for the many-wid compressor.
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unsigned need = cb + // Suffix
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sizeof(BYTE) + // Flags field
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sizeof(BYTE) + // Prefix size
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sizeof(BYTE) + // Suffix size
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sizeof(PROPID) + sizeof(BYTE) + // Property ID (worst case)
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sizeof(BYTE); // WID Count
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return ( (_cur + need) < (_buf + cbInitialBlock ) );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CCompress::OccCountWillFit, private
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//
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// Synopsis: check if the occurrence count will fit into current buffer
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//
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// History: 06-Dec-99 dlee Created
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//
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//----------------------------------------------------------------------------
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inline BOOL CCompress::OccCountWillFit () const
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{
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unsigned need = sizeof(unsigned);
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return ( _cur + need < _buf + cbInitialBlock );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CCompress::WidAndOccCountWillFit, private
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//
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// Synopsis: check if wid and occ count will fit into current buffer
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//
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// History: 07-Aug-91 BartoszM Created
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// 28-May-92 KyleP Adjusted for compression
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//
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//----------------------------------------------------------------------------
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inline BOOL CCompress::WidAndOccCountWillFit () const
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{
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// wid + occCount
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// Note: this isn't called for single wid compressors.
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unsigned need = sizeof(BYTE) + sizeof(unsigned);
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return ( _cur + need < _buf + cbInitialBlock );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CCompress::WidWillFit, private
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//
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// Synopsis: check if wid will fit into current buffer
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//
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// History: 06-Dec-99 dlee Created
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//
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//----------------------------------------------------------------------------
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inline BOOL CCompress::WidWillFit () const
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{
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// wid
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unsigned need = sizeof(BYTE);
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return ( _cur + need < _buf + cbInitialBlock );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CCompress::OccWillFit, private
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//
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// Synopsis: check occ will fit into current buffer
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//
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// History: 07-Aug-91 BartoszM Created
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// 28-May-92 KyleP Adjusted for compression
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//
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//----------------------------------------------------------------------------
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inline BOOL CCompress::OccWillFit( OCCURRENCE occDelta ) const
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{
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unsigned next;
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if ( occDelta <= (1 << 8) - 1 )
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next = 1;
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else if ( occDelta <= (1 << 16) - 1 )
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next = 3;
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else
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next = 7;
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return ( _cur + next < _buf + cbInitialBlock );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CDeCompress::GetKey, public
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//
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// Synopsis: return current key
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//
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// History: 12-Jun-91 BartoszM Created
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//
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//----------------------------------------------------------------------------
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inline const CKeyBuf * CDecompress::GetKey() const
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{
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if( KeyExists() )
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return &_curKey;
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else
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return 0;
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CDeCompress::WorkId, public
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//
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// Synopsis: return current work id
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//
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// History: 12-Jun-91 BartoszM Created
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//
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//----------------------------------------------------------------------------
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inline WORKID CDecompress::WorkId() const
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{
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ciAssert ( KeyExists() );
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return( _curWid );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CDeCompress::Occurrence, public
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//
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// Synopsis: return current occurrence
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//
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// History: 12-Jun-91 BartoszM Created
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//
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//----------------------------------------------------------------------------
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inline OCCURRENCE CDecompress::Occurrence() const
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{
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ciAssert ( KeyExists() );
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return( _curOcc );
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}
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