182 lines
4.7 KiB
C++
182 lines
4.7 KiB
C++
#ifndef _INC_DSKQUOTA_BITSET_H
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#define _INC_DSKQUOTA_BITSET_H
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#ifndef _INC_DSKQUOTA_EXCEPT_H
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# include "except.h"
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#endif
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// Macros & Constants
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// ELEMENT_TYPE
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// This macro defines the type of each "element" in the bit buffer.
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// This type must be an integral type that can be used as an operand
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// in bitwise expressions. If it is changed, the macros
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// ELEMENT_BITNUM_MASK and ELEMENT_SHIFT must also be changed as
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// follows:
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// ELEMENT_TYPE ELEMENT_BITNUM_MASK ELEMENT_SHIFT
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// ---------------- ----------------------- -------------------
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// BYTE 0x00000007 3
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// WORD 0x0000000F 4
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// DWORD 0x0000001F 5
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// ELEMENT_BITNUM_MASK
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// This macro defines the mask used to extract the number of the
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// bit in the array element from the number of the bit being accessed.
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// ELEMENT_SHIFT
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// This macro defines the number of bits to right shift the bit number
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// to obtain the number of the array element.
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#define ELEMENT_TYPE BYTE
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const int ELEMENT_BITNUM_MASK = 0x00000007;
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const int ELEMENT_SHIFT = 3;
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// Forward declaration.
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class BitSet;
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// This is a "helper" class that aids BitSet::operator[]. So that
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// BitSet::operator[] functions properly for both lvalue and rvalue
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// conditions, it returns a "Bit" object. The bit object retains the
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// bit number and a pointer to the "owner" BitSet object. It also
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// overloads the bool conversion operator and assignment operator.
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// Knowing the bit number and the owner BitSet, the class can set or
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// obtain the value of the bit in the BitSet's array.
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class Bit
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{
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public:
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Bit(int iBit, BitSet *pOwnerSet = NULL)
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: m_iBit(iBit),
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m_pOwnerSet(pOwnerSet) { }
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Bit(Bit& bit)
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: m_iBit(bit.m_iBit),
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m_pOwnerSet(bit.m_pOwnerSet) { }
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// Convert value of bit to a bool.
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operator bool () const;
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// Set bit to a bool value.
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bool operator = (bool bState);
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private:
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DWORD m_iBit; // Number of bit in BitSet [0 to n-1]
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BitSet *m_pOwnerSet; // Ptr to BitSet object.
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};
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class BitSet
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{
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public:
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BitSet(int cBits = 1);
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~BitSet(void);
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BitSet(const BitSet& rhs);
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BitSet& operator = (const BitSet& rhs);
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void Initialize(int cBits);
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int Count(void) const
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{ return m_cBits; }
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int CountSet(void) const
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{ return m_cSet; }
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int CountClr(void) const
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{ return m_cBits - m_cSet; }
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bool IsSet(int iBit) const
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{ return GetBitState(iBit); }
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bool IsClr(int iBit) const
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{ return !GetBitState(iBit); }
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void Complement(void);
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// SetBitState and GetBitState are the fastest
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// ways to alter or retrieve the state of a bit.
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void SetBitState(int iBit, bool bSet);
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bool GetBitState(int iBit) const;
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// Set and Clr are the next fastest ways to alter
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// or retrieve the state of a bit.
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void Set(int iBit)
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{ SetBitState(iBit, TRUE); }
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void Clr(int iBit)
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{ SetBitState(iBit, FALSE); }
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// Using the subscript operator is the slowest way
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// to alter/retrieve the state of a bit.
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Bit operator [] (int iBit)
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{ return Bit(iBit, this); }
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void ClrAll(void)
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{ ZeroMemory(m_pBuffer, sizeof(ELEMENT_TYPE) * m_cElements); m_cSet = 0; }
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void SetAll(void)
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{ FillMemory(m_pBuffer, sizeof(ELEMENT_TYPE) * m_cElements, (BYTE)0xFF); m_cSet = m_cBits; }
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#if DBG
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void Dump(void) const;
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#endif
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private:
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ELEMENT_TYPE *m_pBuffer; // Array of elements.
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int m_cBits; // Bits supported in set.
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int m_cSet; // Number of bits set to '1'.
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int m_cElements; // Number of elements in array.
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// Inline functions for calculating bit/element positions in array.
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DWORD BitInElement(int iBit) const
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{ return (iBit & ELEMENT_BITNUM_MASK); }
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DWORD ElementInBuffer(int iBit) const
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{ return (iBit >> ELEMENT_SHIFT); }
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ELEMENT_TYPE MaskFromBit(int iBit) const
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{ return 1 << BitInElement(iBit); }
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void ValidateBitNumber(int iBit) const
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{
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if (iBit >= m_cBits)
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throw CMemoryException(CMemoryException::index);
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}
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friend class Bit;
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};
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inline
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Bit::operator bool () const
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{
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return m_pOwnerSet->GetBitState(m_iBit);
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}
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inline bool
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Bit::operator = (bool bState)
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{
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m_pOwnerSet->SetBitState(m_iBit, bState);
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return bState;
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}
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#endif // _INC_DSKQUOTA_BITSET_H
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