/****************************************************************************
** $Id: qbitarray.cpp,v 1.3 2002/07/16 00:28:41 thiagocorrea Exp $
**
** Implementation of QBitArray class
**
** Created : 940118
**
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**
** This file is part of the tools module of the Qt GUI Toolkit.
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** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
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** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
** licenses may use this file in accordance with the Qt Commercial License
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**   information about Qt Commercial License Agreements.
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**********************************************************************/

#include "qbitarray.h"
#include "qdatastream.h"

#define SHBLOCK	 ((bitarr_data*)(sharedBlock()))


// NOT REVISED
/*!
  \class QBitVal qbitarray.h
  \ingroup collection
  \brief The QBitVal class is an internal class, used with QBitArray.

  The QBitVal is required by the indexing [] operator on bit arrays.
  Don't use it in any other context.
*/

/*!
  \fn QBitVal::QBitVal (QBitArray* a, uint i)

  Constructs a reference to element \a i in the QBitArray \a a.  This
  is what QBitArray::operator[] constructs its return value with.
*/

/*!
  \fn QBitVal::operator int()

  Returns the value referenced by the QBitVal.
*/

/*!
  \fn QBitVal& QBitVal::operator= (const QBitVal& v)

  Sets the value referenced by the QBitVal to that referenced by
  QBitVal \a v.
*/

/*!
  \overload QBitVal& QBitVal::operator= (bool v)

  Sets the value referenced by the QBitVal to \a v.
*/


/*!
  \class QBitArray qbitarray.h
  \ingroup collection
  \brief The QBitArray class provides an array of bits.

  \ingroup tools
  \ingroup shared

  Because QBitArray is a QMemArray, it uses explicit
  \link shclass.html sharing\endlink with a reference count.

  A QBitArray is a special byte array that can access individual bits
  and perform bit-operations (AND, OR, XOR and NOT) on entire
  arrays or bits.

  Bits can be manipulated by the setBit() and clearBit() functions, but it
  is also possible to use the indexing [] operator to test and set
  individual bits. The [] operator is a little slower than setBit() and
  clearBit() because some tricks are required to implement single-bit
  assignments.

  Example:
  \code
    QBitArray a(3);
    a.setBit( 0 );
    a.clearBit( 1 );
    a.setBit( 2 );			// a = [1 0 1]

    QBitArray b(3);
    b[0] = 1;
    b[1] = 1;
    b[2] = 0;				// b = [1 1 0]

    QBitArray c;
    c = ~a & b;				// c = [0 1 0]
  \endcode

  When a QBitArray is constructed the bits are uninitialized. Use fill()
  to set all the bits to 0 or 1. The array can be resized with resize()
  and copied with copy(). Bits can be set with setBit() and cleared with
  clearBit(). Bits can be toggled with toggleBit(). A bit's value can be
  obtained with testBit() and with at().

  QBitArray supports the \& (AND), | (OR), ^ (XOR) and ~ (NOT) operators.
*/

/*! \class QBitArray::bitarr_data
  \brief The QBitArray::bitarr_data class is internal.
  \internal
*/


/*!
  Constructs an empty bit array.
*/

QBitArray::QBitArray() : QByteArray( 0, 0 )
{
    bitarr_data *x = new bitarr_data;
    Q_CHECK_PTR( x );
    x->nbits = 0;
    setSharedBlock( x );
}

/*!
  Constructs a bit array of \a size bits. The bits are uninitialized.

  \sa fill()
*/

QBitArray::QBitArray( uint size ) : QByteArray( 0, 0 )
{
    bitarr_data *x = new bitarr_data;
    Q_CHECK_PTR( x );
    x->nbits = 0;
    setSharedBlock( x );
    resize( size );
}

/*!
  \fn QBitArray::QBitArray( const QBitArray &a )
  Constructs a shallow copy of \a a.
*/

/*!
  \fn QBitArray &QBitArray::operator=( const QBitArray &a )
  Assigns a shallow copy of \a a to this bit array and returns a reference
  to this array.
*/


/*!
  Pad last byte with 0-bits.
*/
void QBitArray::pad0()
{
    uint sz = size();
    if ( sz && sz%8 )
	*(data()+sz/8) &= (1 << (sz%8)) - 1;
}


/*!
  \fn uint QBitArray::size() const
  Returns the size (number of bits) of the bit array.
  \sa resize()
*/

/*!  Resizes the bit array to \a size bits and returns TRUE if the bit
  array could be resized, and FALSE otherwise.

  If the array is expanded, the new bits are set to 0.

  \sa size()
*/

bool QBitArray::resize( uint size )
{
    uint s = this->size();
    if ( !QByteArray::resize( (size+7)/8 ) )
	return FALSE;				// cannot resize
    SHBLOCK->nbits = size;
    if ( size != 0 ) {				// not null array
	int ds = (int)(size+7)/8 - (int)(s+7)/8;// number of bytes difference
	if ( ds > 0 )				// expanding array
	    memset( data() + (s+7)/8, 0, ds );	//   reset new data
    }
    return TRUE;
}


/*!
  Fills the bit array with \a v (1's if \a v is TRUE, or 0's if \a v is
  FALSE).

  fill() resizes the bit array to \a size bits if \a size is nonnegative.

  Returns FALSE if a nonnegative \e size was specified and the bit array
  could not be resized; otherwise returns TRUE.

  \sa resize()
*/

bool QBitArray::fill( bool v, int size )
{
    if ( size >= 0 ) {				// resize first
	if ( !resize( size ) )
	    return FALSE;			// cannot resize
    } else {
	size = this->size();
    }
    if ( size > 0 )
	memset( data(), v ? 0xff : 0, (size + 7) / 8 );
    if ( v )
	pad0();
    return TRUE;
}


/*!
  Detaches from shared bit array data and makes sure that this bit array
  is the only one referring to the data.

  If multiple bit arrays share common data, this bit array dereferences the
  data and gets a copy of the data. Nothing will be done if there is just
  a single reference.

  \sa copy()
*/

void QBitArray::detach()
{
    int nbits = SHBLOCK->nbits;
    this->duplicate( *this );
    SHBLOCK->nbits = nbits;
}

/*!
  Returns a deep copy of the bit array.
  \sa detach()
*/

QBitArray QBitArray::copy() const
{
    QBitArray tmp;
    tmp.duplicate( *this );
    ((bitarr_data*)(tmp.sharedBlock()))->nbits = SHBLOCK->nbits;
    return tmp;
}


/*!
  Returns TRUE if the bit at position \a index is set, i.e. is 1.
  \sa setBit(), clearBit()
*/

bool QBitArray::testBit( uint index ) const
{
#if defined(QT_CHECK_RANGE)
    if ( index >= size() ) {
	qWarning( "QBitArray::testBit: Index %d out of range", index );
	return FALSE;
    }
#endif
    return (*(data()+(index>>3)) & (1 << (index & 7))) != 0;
}

/*!
    \overload
  Sets the bit at position \a index (sets it to 1).
  \sa clearBit() toggleBit()
*/

void QBitArray::setBit( uint index )
{
#if defined(QT_CHECK_RANGE)
    if ( index >= size() ) {
	qWarning( "QBitArray::setBit: Index %d out of range", index );
	return;
    }
#endif
    *(data()+(index>>3)) |= (1 << (index & 7));
}

/*!
  \fn void QBitArray::setBit( uint index, bool value )
  Sets the bit at position \a index to \a value.

  Equivalent to:
  \code
    if ( value )
	setBit( index );
    else
	clearBit( index );
  \endcode

  \sa clearBit() toggleBit()
*/

/*!
  Clears the bit at position \a index (sets it to 0).
  \sa setBit(), toggleBit()
*/

void QBitArray::clearBit( uint index )
{
#if defined(QT_CHECK_RANGE)
    if ( index >= size() ) {
	qWarning( "QBitArray::clearBit: Index %d out of range", index );
	return;
    }
#endif
    *(data()+(index>>3)) &= ~(1 << (index & 7));
}

/*!
  Toggles the bit at position \a index.

  If the previous value was 0, the new value will be 1.	 If the previous
  value was 1, the new value will be 0.

  \sa setBit(), clearBit()
*/

bool QBitArray::toggleBit( uint index )
{
#if defined(QT_CHECK_RANGE)
    if ( index >= size() ) {
	qWarning( "QBitArray::toggleBit: Index %d out of range", index );
	return FALSE;
    }
#endif
    register uchar *p = (uchar *)data() + (index>>3);
    uchar b = (1 << (index & 7));		// bit position
    uchar c = *p & b;				// read bit
    *p ^= b;					// toggle bit
    return c;
}


/*!
  \fn bool QBitArray::at( uint index ) const
  Returns the value (0 or 1) of the bit at position \a index.
  \sa operator[]()
*/

/*!
  \fn QBitVal QBitArray::operator[]( int index )
  Implements the [] operator for bit arrays.

  The returned QBitVal is a context object. It makes it possible to get
  and set a single bit value by its \a index position.

  Example:
  \code
    QBitArray a( 3 );
    a[0] = 0;
    a[1] = 1;
    a[2] = a[0] ^ a[1];
  \endcode

  The functions testBit(), setBit() and clearBit() are faster.

  \sa at()
*/

/*!
    \overload bool QBitArray::operator[]( int index ) const
  Implements the [] operator for constant bit arrays.
*/


/*!
  Performs the AND operation between all bits in this bit array and \a a.
  Returns a reference to this bit array.

  If the arrays have different sizes, the AND operation uses 0 for the
  missing bits, as the following example demonstrates:
  \code
    QBitArray a( 3 ), b( 2 );
    a[0] = 1;  a[1] = 0;  a[2] = 1;     // a = [1 0 1]
    b[0] = 1;  b[1] = 0;                // b = [1 0]
    a &= b;                             // a = [1 0 0]
  \endcode

  \sa operator|=(), operator^=(), operator~()
*/

QBitArray &QBitArray::operator&=( const QBitArray &a )
{
    resize( QMAX(size(), a.size()) );
    register uchar *a1 = (uchar *)data();
    register uchar *a2 = (uchar *)a.data();
    int n = QMIN( QByteArray::size(), a.QByteArray::size() );
    int p = QMAX( QByteArray::size(), a.QByteArray::size() ) - n;
    while ( n-- > 0 )
	*a1++ &= *a2++;
    while ( p-- > 0 )
	*a1++ = 0;
    return *this;
}

/*!
  Performs the OR operation between all bits in this bit array and \a a.
  Returns a reference to this bit array.

  The result has the length of the longest bit array of the two, with
  the bits missing from the shortest array taken as 0.

  Example:
  \code
    QBitArray a( 3 ), b( 2 );
    a[0] = 1;  a[1] = 0;  a[2] = 1;     // a = [1 0 1]
    b[0] = 1;  b[1] = 0;                // b = [1 0]
    a |= b;                             // a = [1 0 1]
  \endcode

  \sa operator&=(), operator^=(), operator~()
*/

QBitArray &QBitArray::operator|=( const QBitArray &a )
{
    resize( QMAX(size(), a.size()) );
    register uchar *a1 = (uchar *)data();
    register uchar *a2 = (uchar *)a.data();
    int n = QMIN( QByteArray::size(), a.QByteArray::size() );
    while ( n-- > 0 )
	*a1++ |= *a2++;
    return *this;
}

/*!
  Performs the XOR operation between all bits in this bit array and \a a.
  Returns a reference to this bit array.

  The result has the length of the longest bit array of the two, with
  the bits missing from the shortest array taken as 0.

  Example:
  \code
    QBitArray a( 3 ), b( 2 );
    a[0] = 1;  a[1] = 0;  a[2] = 1;     // a = [1 0 1]
    b[0] = 1;  b[1] = 0;                // b = [1 0]
    a ^= b;                             // a = [0 0 1]
  \endcode

  \sa operator&=(), operator|=(), operator~()
*/

QBitArray &QBitArray::operator^=( const QBitArray &a )
{
    resize( QMAX(size(), a.size()) );
    register uchar *a1 = (uchar *)data();
    register uchar *a2 = (uchar *)a.data();
    int n = QMIN( QByteArray::size(), a.QByteArray::size() );
    while ( n-- > 0 )
	*a1++ ^= *a2++;
    return *this;
}

/*!
  Returns a bit array that contains the inverted bits of this bit array.

  Example:
  \code
    QBitArray a( 3 ), b;
    a[0] = 1;  a[1] = 0; a[2] = 1;	// a = [1 0 1]
    b = ~a;				// b = [0 1 0]
  \endcode
*/

QBitArray QBitArray::operator~() const
{
    QBitArray a( size() );
    register uchar *a1 = (uchar *)data();
    register uchar *a2 = (uchar *)a.data();
    int n = QByteArray::size();
    while ( n-- )
	*a2++ = ~*a1++;
    a.pad0();
    return a;
}


/*!
  \relates QBitArray
  Returns the AND result between the bit arrays \a a1 and \a a2.
  \sa QBitArray::operator&=()
*/

QBitArray operator&( const QBitArray &a1, const QBitArray &a2 )
{
    QBitArray tmp = a1.copy();
    tmp &= a2;
    return tmp;
}

/*!
  \relates QBitArray
  Returns the OR result between the bit arrays \a a1 and \a a2.
  \sa QBitArray::operator|=()
*/

QBitArray operator|( const QBitArray &a1, const QBitArray &a2 )
{
    QBitArray tmp = a1.copy();
    tmp |= a2;
    return tmp;
}

/*!
  \relates QBitArray
  Returns the XOR result between the bit arrays \a a1 and \a a2.
  \sa QBitArray::operator^()
*/

QBitArray operator^( const QBitArray &a1, const QBitArray &a2 )
{
    QBitArray tmp = a1.copy();
    tmp ^= a2;
    return tmp;
}


/* \enum QGArray::array_data

  \warning This will be renamed in the next major release of Qt.  Until
  then it is undocumented and we recommend against its use.

  \internal

  ### 3.0 rename ###
  ### 3.0 move it to QGArray? ###
*/


/*! \fn QBitArray::array_data * QBitArray::newData()

  Returns data specific to QBitArray that extends what QGArray provides.
  \internal
  QPtrCollection mechanism for allowing extra/different data.
*/


/*! \fn void  QBitArray::deleteData ( array_data * d )

  Deletes data specific to QBitArray that extended what QGArray provided.
  \internal
  QPtrCollection mechanism for allowing extra/different data.
*/


/*****************************************************************************
  QBitArray stream functions
 *****************************************************************************/

/*!
  \relates QBitArray
  Writes bit array \a a to stream \a s.

  \sa \link datastreamformat.html Format of the QDataStream operators \endlink
*/
#ifndef QT_NO_DATASTREAM
QDataStream &operator<<( QDataStream &s, const QBitArray &a )
{
    Q_UINT32 len = a.size();
    s << len;					// write size of array
    if ( len > 0 )				// write data
	s.writeRawBytes( a.data(), a.QByteArray::size() );
    return s;
}

/*!
  \relates QBitArray
  Reads a bit array into \a a from stream \a s.

  \sa \link datastreamformat.html Format of the QDataStream operators \endlink
*/

QDataStream &operator>>( QDataStream &s, QBitArray &a )
{
    Q_UINT32 len;
    s >> len;					// read size of array
    if ( !a.resize( (uint)len ) ) {		// resize array
#if defined(QT_CHECK_NULL)
	qWarning( "QDataStream: Not enough memory to read QBitArray" );
#endif
	len = 0;
    }
    if ( len > 0 )				// read data
	s.readRawBytes( a.data(), a.QByteArray::size() );
    return s;
}

#endif // QT_NO_DATASTREAM
