215 lines
4.9 KiB
C++
215 lines
4.9 KiB
C++
//+-------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1992 - 1994.
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//
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// File: KeyHash.hxx
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//
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// Contents: Persistent key hash table
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//
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// History: 17-Feb-94 KyleP Created
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//
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//--------------------------------------------------------------------------
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#pragma once
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#include <bitoff.hxx>
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#include <misc.hxx>
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#include "keylist.hxx"
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#include "physidx.hxx"
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#include "bitstm.hxx"
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#define BITS_IN_CI_PAGE_SIZE 12 // Number of bits in CI_PAGE_SIZE
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#define CI_PAGE_MASK 0x0FFF //
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//+-------------------------------------------------------------------------
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//
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// Class: CKeyHash
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//
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// Purpose: Base key hash class
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//
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// History: 17-Feb-94 KyleP Created
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//
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// Notes: The key hash is an array. It is referenced by key id and
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// contains the index of the directory (PDir) leaf node which
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// points to the page on which key kid is stored.
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//
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// Each entry is Log2(# directory leaf nodes) long.
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//
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//--------------------------------------------------------------------------
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class CKeyHash : INHERIT_UNWIND
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{
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DECLARE_UNWIND
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public:
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CKeyHash( unsigned cDirEntry );
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inline unsigned BitsPerEntry() const;
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protected:
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inline BitOffset KidToOff( KEYID kid );
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unsigned const _cBitsPerEntry;
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private:
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inline unsigned Size( unsigned cDirEntry );
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};
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//+-------------------------------------------------------------------------
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//
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// Class: CRKeyHash
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//
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// Purpose: Readable key hash
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//
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// History: 17-Feb-94 KyleP Created
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//
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//--------------------------------------------------------------------------
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class CRKeyHash : public CKeyHash
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{
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DECLARE_UNWIND
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public:
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CRKeyHash( CPhysHash & physHash, unsigned cDirEntry );
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//
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// Lookup
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//
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void Find( KEYID kid, BitOffset & off);
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private:
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CRBitStream _bitstm;
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};
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//+-------------------------------------------------------------------------
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//
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// Class: CWKeyHash
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//
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// Purpose: Writeable key hash
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//
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// History: 17-Feb-94 KyleP Created
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//
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//--------------------------------------------------------------------------
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class CWKeyHash : public CKeyHash
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{
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DECLARE_UNWIND
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public:
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CWKeyHash( CPhysHash & physHash, unsigned cDirEntry, KEYID kidMax );
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void Add( KEYID kid, BitOffset & bitOff );
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private:
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CPBitStream _bitstm;
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};
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//+-------------------------------------------------------------------------
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//
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// Method: CKeyHash::BitsPerEntry
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//
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// Returns: Bits required to store each key hash
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//
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// History: 17-Feb-1994 KyleP Created
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//
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//--------------------------------------------------------------------------
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inline unsigned CKeyHash::BitsPerEntry() const
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{
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return( _cBitsPerEntry );
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}
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//+-------------------------------------------------------------------------
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//
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// Method: CKeyHash::SetSize
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//
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// Synopsis: Sets maximum number of unique hash values
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//
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// Arguments: [cNumPages] -- # of pages in the keylist stream
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//
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// History: 17-Feb-1994 KyleP Created
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// 30-May-1994 DwightKr Added BITS_IN_CI_PAGE_SIZE so
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// that offsets in addition to page
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// #'s are stored.
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//
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//--------------------------------------------------------------------------
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inline unsigned CKeyHash::Size( unsigned cNumPages )
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{
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unsigned c = Log2( cNumPages );
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if ( c == 0 )
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c = 1;
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c += BITS_IN_CI_PAGE_SIZE;
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ciDebugOut(( DEB_KEYLIST, "KeyHash: %d dir entries --> %d bits/entry\n",
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cNumPages, c ));
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Win4Assert(c <= (sizeof(ULONG) * 8) );
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return( c );
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}
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//+-------------------------------------------------------------------------
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//
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// Method: CKeyHash::KidToOff
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//
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// Arguments: [kid] -- Key id
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//
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// Returns: Bit offset of position where hash for [kid] is stored
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//
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// History: 17-Feb-1994 KyleP Created
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//
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//--------------------------------------------------------------------------
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inline BitOffset CKeyHash::KidToOff( KEYID kid )
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{
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BitOffset off;
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//
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// WARNING: If kid > 2^27 (~ 134,000,000) this will overflow.
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//
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off.Init( (kid * _cBitsPerEntry) / (CI_PAGE_SIZE * 8),
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(kid * _cBitsPerEntry) % (CI_PAGE_SIZE * 8) );
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return( off );
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}
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//+---------------------------------------------------------------------------
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//
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// Class: PKeyHash
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//
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// Purpose: Smart Pointer to key list
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//
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// History: 28-Oct-93 w-PatG Stolen from BartoszM
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//
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//----------------------------------------------------------------------------
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class PRKeyHash : INHERIT_UNWIND
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{
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DECLARE_UNWIND
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public:
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PRKeyHash ( CRKeyHash * pKeyHash )
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{
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_pKeyHash = pKeyHash;
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END_CONSTRUCTION( PRKeyHash );
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}
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~PRKeyHash () { delete _pKeyHash; }
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CRKeyHash * operator-> () { return _pKeyHash; }
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private:
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CRKeyHash * _pKeyHash;
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};
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