//===== Copyright © 1996-2005, Valve Corporation, All rights reserved. ======//
//
// Purpose: 
//
//===========================================================================//

#ifndef BITVEC_H
#define BITVEC_H
#ifdef _WIN32
#pragma once
#endif

#include "tier0/dbg.h"
#include "tier0/basetypes.h"


class CBitVecAccessor
{
public:
				CBitVecAccessor(unsigned long *pDWords, int iBit);

	void		operator=(int val);
				operator unsigned long();

private:
	unsigned long	*m_pDWords;
	int				m_iBit;
};
	

// CBitVec allows you to store a list of bits and do operations on them like they were an atomic type.
template<int NUM_BITS>
class CBitVec
{
public:
	
					CBitVec();

	// Get a pointer to the raw bits.
	unsigned long*	Base();

	// Set all values to the specified value (0 or 1..)
	void			Init(int val = 0);

	// Access the bits like an array.
	CBitVecAccessor	operator[](int i);

	// Clear or set all bits.
	void			ClearAll( int nBits=NUM_BITS );
	void			SetAll( int nBits=NUM_BITS );
	
	// Get the state of a bit.
	unsigned long	Get( unsigned long iBit ) const;
	bool			IsBitSet( unsigned long iBit ) const;

	// Set or clear a bit.
	void			Set( unsigned long iBit );
	void			Clear( unsigned long iBit );

	// Set a bit either on or off.
	void			Set( unsigned long iBit, int bOn );

	// Copy the state of another CBitVec.
	void			Copy( CBitVec<NUM_BITS> const &other, int nBits=NUM_BITS );

	// Returns true if the bit vectors have the same values.
	bool			Compare( CBitVec<NUM_BITS> const &other, int nBits=NUM_BITS );

	// Operations on other bit vectors.
	CBitVec&		operator=(CBitVec<NUM_BITS> const &other);
	bool			operator==(CBitVec<NUM_BITS> const &other);
	bool			operator!=(CBitVec<NUM_BITS> const &other);

	// Get underlying dword representations of the bits.
	int				GetNumDWords() const;
	unsigned long	GetDWord(int i) const;
	void			SetDWord(int i, unsigned long val);

	int				GetNumBits() const;

	int				FindNextSetBit(int iStartBit) const; // returns -1 if no set bit was found

private:

	enum			{NUM_DWORDS = NUM_BITS/32 + !!(NUM_BITS & 31)};
	unsigned long	m_DWords[NUM_DWORDS];
};



// ------------------------------------------------------------------------ //
// CBitVecAccessor inlines.
// ------------------------------------------------------------------------ //

inline CBitVecAccessor::CBitVecAccessor(unsigned long *pDWords, int iBit)
{
	m_pDWords = pDWords;
	m_iBit = iBit;
}


inline void CBitVecAccessor::operator=(int val)
{
	if(val)
		m_pDWords[m_iBit >> 5] |= (1 << (m_iBit & 31));
	else
		m_pDWords[m_iBit >> 5] &= ~(unsigned long)(1 << (m_iBit & 31));
}

inline CBitVecAccessor::operator unsigned long()
{
	return m_pDWords[m_iBit >> 5] & (1 << (m_iBit & 31));
}



// ------------------------------------------------------------------------ //
// CBitVec inlines.
// ------------------------------------------------------------------------ //

template<int NUM_BITS>
inline int CBitVec<NUM_BITS>::GetNumBits() const
{
	return NUM_BITS;
}


template<int NUM_BITS>
inline CBitVec<NUM_BITS>::CBitVec()
{
	for(int i=0; i < NUM_DWORDS; i++)
		m_DWords[i] = 0;
}


template<int NUM_BITS>
inline void CBitVec<NUM_BITS>::Init(int val)
{
	unsigned long dwVal = val ? 0xFFFFFFFF : 0;
	for( int i=0; i < NUM_DWORDS; i++ )
		m_DWords[i] = dwVal;
}


template<int NUM_BITS>
inline unsigned long* CBitVec<NUM_BITS>::Base()
{
	return m_DWords;
}


template<int NUM_BITS>
inline CBitVec<NUM_BITS>& CBitVec<NUM_BITS>::operator=(CBitVec<NUM_BITS> const &other)
{
	memcpy(m_DWords, other.m_DWords, sizeof(m_DWords));
	return *this;
}


template<int NUM_BITS>
inline CBitVecAccessor CBitVec<NUM_BITS>::operator[](int i)	
{
	Assert(i >= 0 && i < GetNumBits());
	return CBitVecAccessor(m_DWords, i);
}


template< int SIZE >
inline void CBitVec<SIZE>::ClearAll( int nBits )
{
	int nDWords = PAD_NUMBER( nBits, 32 ) >> 5;
	Assert( nDWords <= NUM_DWORDS );
	
	for( int i=0; i < nDWords; i++ )
		m_DWords[i] = 0;
}

template< int SIZE >
inline void CBitVec<SIZE>::SetAll( int nBits )
{
	int nDWords = PAD_NUMBER( nBits, 32 ) >> 5;
	Assert( nDWords <= NUM_DWORDS );
	
	for( int i=0; i < nDWords; i++ )
		m_DWords[i] = 0xFFFFFFFF;
}

template< int SIZE >
inline unsigned long CBitVec<SIZE>::Get( unsigned long iBit ) const
{
	Assert( iBit < SIZE );
	return m_DWords[iBit >> 5] & (1 << (iBit & 31));
}

template< int SIZE >
bool CBitVec<SIZE>::IsBitSet( unsigned long iBit ) const
{
	return ( m_DWords[iBit >> 5] & (1 << (iBit & 31)) ) != 0;
}

template< int SIZE >
inline void CBitVec<SIZE>::Set( unsigned long iBit )
{
	Assert( iBit < SIZE );
	m_DWords[iBit >> 5] |= (1 << (iBit & 31));
}

template< int SIZE >
inline void CBitVec<SIZE>::Clear( unsigned long iBit )
{
	Assert( iBit < SIZE );
	m_DWords[iBit >> 5] &= ~(1 << (iBit & 31));
}

template< int SIZE >
inline void CBitVec<SIZE>::Set( unsigned long iBit, int bOn )
{
	if( bOn )
		Set( iBit );
	else
		Clear( iBit );
}

template< int SIZE >
inline void CBitVec<SIZE>::Copy( CBitVec<SIZE> const &other, int nBits )
{
	int nBytes = PAD_NUMBER( nBits, 8 ) >> 3;
	Assert( nBytes <= NUM_DWORDS*4 );
	memcpy( m_DWords, other.m_DWords, nBytes );
}


template< int SIZE >
inline bool CBitVec<SIZE>::Compare( CBitVec<SIZE> const &other, int nBits )
{
	int nBytes = PAD_NUMBER( nBits, 8 ) >> 3;
	Assert( nBytes <= NUM_DWORDS*4 );

	return memcmp( m_DWords, other.m_DWords, nBytes ) == 0;
}


template<int NUM_BITS>
inline bool CBitVec<NUM_BITS>::operator==(CBitVec<NUM_BITS> const &other)
{
	for(int i=0; i < NUM_DWORDS; i++)
		if(m_DWords[i] != other.m_DWords[i])
			return false;

	return true;
}


template<int NUM_BITS>
inline bool CBitVec<NUM_BITS>::operator!=(CBitVec<NUM_BITS> const &other)
{
	return !(*this == other);
}


template<int NUM_BITS>
inline int CBitVec<NUM_BITS>::GetNumDWords() const
{
	return NUM_DWORDS;
}

template<int NUM_BITS>
inline unsigned long CBitVec<NUM_BITS>::GetDWord(int i) const
{
	Assert(i >= 0 && i < NUM_DWORDS);
	return m_DWords[i];
}


template<int NUM_BITS>
inline void CBitVec<NUM_BITS>::SetDWord(int i, unsigned long val)
{
	Assert(i >= 0 && i < NUM_DWORDS);
	m_DWords[i] = val;
}

template<int NUM_BITS>
inline int CBitVec<NUM_BITS>::FindNextSetBit(int iStartBit) const
{
	int currentBit = iStartBit;

	while (currentBit < NUM_BITS)
	{
		// Early out for lots of zeros in a row
		// check for 32 bit boundary...
		if ( (currentBit & 31) == 0)
		{
			if (m_DWords[currentBit>>5] == 0)
			{
				currentBit += 32;
				continue;
			}
		}

		// One bit at a time...until we reach next DWord border
		do 
		{
			if( m_DWords[currentBit >> 5] & (1 << (currentBit & 31)) )
				return currentBit; // found a set bit

			++currentBit; // next please
			
		} while ( (currentBit & 31) != 0 );
	}

	return -1; // no bit set in rest of bit array
}



#endif // BITVEC_H