131 lines
2.8 KiB
C++
131 lines
2.8 KiB
C++
//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1996 - 1999.
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//
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// File: circq.hxx
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//
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// Contents: First-in-first-out circular queue template
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//
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// History: 96/Apr/12 dlee Created
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//
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//----------------------------------------------------------------------------
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#pragma once
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template<class T> class TFifoCircularQueue
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{
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public:
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TFifoCircularQueue( unsigned maxRequests ) :
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_cRequests( 0 ),
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_iFirst( 0 ),
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_maxRequests( maxRequests ),
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_fEnableAdditions( TRUE )
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{
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_aEntries = new T [ _maxRequests ];
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RtlZeroMemory( _aEntries, sizeof T * _maxRequests );
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}
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~TFifoCircularQueue()
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{
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delete [] _aEntries;
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}
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BOOL Any() const { return 0 != _cRequests; }
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unsigned Count() { return _cRequests; }
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unsigned MaxRequests() { return _maxRequests; }
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void DisableAdditions()
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{
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CLock lock( _mutex );
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_fEnableAdditions = FALSE;
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}
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void EnableAdditions()
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{
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CLock lock( _mutex );
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_fEnableAdditions = TRUE;
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}
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BOOL IsFull( )
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{
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// NOTE - locking not needed for read access.
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Win4Assert( _cRequests <= _maxRequests );
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return ( _maxRequests == _cRequests );
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}
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BOOL Add( T & Entry )
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{
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CLock lock( _mutex );
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if ( _maxRequests == _cRequests || !_fEnableAdditions )
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return FALSE;
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Win4Assert( _cRequests < _maxRequests );
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unsigned iNew = ( _iFirst + _cRequests ) % _maxRequests;
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Win4Assert( iNew < _maxRequests );
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Entry.Acquire( _aEntries[ iNew ] );
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_cRequests++;
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return TRUE;
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}
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BOOL RemoveTop( T & Entry )
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{
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CLock lock( _mutex );
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if ( 0 == _cRequests )
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return FALSE;
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Entry = _aEntries[ _iFirst ];
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RtlZeroMemory( &_aEntries[ _iFirst ], sizeof T );
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_iFirst++;
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_cRequests--;
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if ( _maxRequests == _iFirst )
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_iFirst = 0;
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Win4Assert( _iFirst < _maxRequests );
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return TRUE;
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}
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BOOL AcquireTop( T & item )
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{
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CLock lock( _mutex );
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if ( 0 == _cRequests )
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return FALSE;
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_aEntries[ _iFirst ].Acquire( item );
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_iFirst++;
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_cRequests--;
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if ( _maxRequests == _iFirst )
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_iFirst = 0;
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Win4Assert( _iFirst < _maxRequests );
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return TRUE;
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}
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private:
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unsigned _cRequests;
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unsigned _iFirst;
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unsigned _maxRequests;
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BOOL _fEnableAdditions;
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T * _aEntries;
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CMutexSem _mutex;
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};
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