qbitarray.cpp

奇趣公司比较新的qt/emd版本

/****************************************************************************
**
** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file.  Please review the following information to ensure GNU
** General Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at [e-mail].
**
** In addition, as a special exception, Trolltech gives you certain
** additional rights. These rights are described in the Trolltech GPL
** Exception version 1.0, which can be found at
** http://www.trolltech.com/products/qt/gplexception/ and in the file
** GPL_EXCEPTION.txt in this package.
**
** In addition, as a special exception, Trolltech, as the sole copyright
** holder for Qt Designer, grants users of the Qt/Eclipse Integration
** plug-in the right for the Qt/Eclipse Integration to link to
** functionality provided by Qt Designer and its related libraries.
**
** Trolltech reserves all rights not expressly granted herein.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "qbitarray.h"
#include <qdatastream.h>
#include <qdebug.h>
#include <string.h>

/*!
    \class QBitArray
    \brief The QBitArray class provides an array of bits.

    \ingroup tools
    \ingroup shared
    \reentrant

    A QBitArray is an array that gives access to individual bits and
    provides operators (\link operator&() AND\endlink, \link
    operator|() OR\endlink, \link operator^() XOR\endlink, and \link
    operator~() NOT\endlink) that work on entire arrays of bits. It
    uses \l{implicit sharing} (copy-on-write) to reduce memory usage
    and to avoid the needless copying of data.

    The following code constructs a QBitArray containing 200 bits
    initialized to false (0):

    \code
        QBitArray ba(200);
    \endcode

    To initialize the bits to true, either pass \c true as second
    argument to the constructor, or call fill() later on.

    QBitArray uses 0-based indexes, just like C++ arrays. To access
    the bit at a particular index position, you can use operator[]().
    On non-const bit arrays, operator[]() returns a reference to a
    bit that can be used on the left side of an assignment. For
    example:

    \code
        QBitArray ba;
        ba.resize(3);
        ba[0] = true;
        ba[1] = false;
        ba[2] = true;
    \endcode

    For technical reasons, it is more efficient to use testBit() and
    setBit() to access bits in the array than operator[](). For
    example:

    \code
        QBitArray ba(3);
        ba.setBit(0, true);
        ba.setBit(1, false);
        ba.setBit(2, true);
    \endcode

    QBitArray supports \c{&} (\link operator&() AND\endlink), \c{|}
    (\link operator|() OR\endlink), \c{^} (\link operator^()
    XOR\endlink), \c{~} (\link operator~() NOT\endlink), as well as
    \c{&=}, \c{|=}, and \c{^=}. These operators work in the same way
    as the built-in C++ bitwise operators of the same name. For
    example:

    \code
        QBitArray x(5);
        x.setBit(3, true);
        // x: [ 0, 0, 0, 1, 0 ]

        QBitArray y(5);
        y.setBit(4, true);
        // y: [ 0, 0, 0, 0, 1 ]

        x |= y;
        // x: [ 0, 0, 0, 1, 1 ]
    \endcode

    For historical reasons, QBitArray distinguishes between a null
    bit array and an empty bit array. A \e null bit array is a bit
    array that is initialized using QBitArray's default constructor.
    An \e empty bit array is any bit array with size 0. A null bit
    array is always empty, but an empty bit array isn't necessarily
    null:

    \code
        QBitArray().isNull();           // returns true
        QBitArray().isEmpty();          // returns true

        QBitArray(0).isNull();          // returns false
        QBitArray(0).isEmpty();         // returns true

        QBitArray(3).isNull();          // returns false
        QBitArray(3).isEmpty();         // returns false
    \endcode

    All functions except isNull() treat null bit arrays the same as
    empty bit arrays; for example, QBitArray() compares equal to
    QBitArray(0). We recommend that you always use isEmpty() and
    avoid isNull().

    \sa QByteArray, QVector
*/

/*! \fn QBitArray::QBitArray()

    Constructs an empty bit array.

    \sa isEmpty()
*/

/*!
    Constructs a bit array containing \a size bits. The bits are
    initialized with \a value, which defaults to false (0).
*/
QBitArray::QBitArray(int size, bool value)
{
    if (!size) {
        d.resize(0);
        return;
    }
    d.resize(1 + (size+7)/8);
    uchar* c = reinterpret_cast<uchar*>(d.data());
    memset(c, value ? 0xff : 0, d.size());
    *c = d.size()*8 - size;
    if (value && size && size % 8)
        *(c+1+size/8) &= (1 << (size%8)) - 1;
}

/*! \fn int QBitArray::size() const

    Returns the number of bits stored in the bit array.

    \sa resize()
*/

/*! \fn int QBitArray::count() const

    Same as size().
*/

/*!
    If \a on is true, this function returns the number of
    1-bits stored in the bit array; otherwise the number
    of 0-bits is returned.
*/
int QBitArray::count(bool on) const
{
    int numBits = 0;
    int len = size();
#if 0
    for (int i = 0; i < len; ++i)
        numBits += testBit(i);
#else
    // See http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
    const quint8 *bits = reinterpret_cast<const quint8 *>(d.data()) + 1;
    while (len >= 32) {
        quint32 v = quint32(bits[0]) | (quint32(bits[1]) << 8) | (quint32(bits[2]) << 16) | (quint32(bits[3]) << 24);
        quint32 c = ((v & 0xfff) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        c += (((v & 0xfff000) >> 12) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        c += ((v >> 24) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        len -= 32;
        bits += 4;
        numBits += int(c);
    }
    while (len >= 24) {
        quint32 v = quint32(bits[0]) | (quint32(bits[1]) << 8) | (quint32(bits[2]) << 16);
        quint32 c =  ((v & 0xfff) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        c += (((v & 0xfff000) >> 12) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;    
        len -= 24;
        bits += 3;
        numBits += int(c);
    }
    while (len >= 0) {
        if (bits[len / 8] & (1 << ((len - 1) & 7)))
            ++numBits;
        --len;
    }
#endif
    return on ? numBits : size() - numBits;
}

/*!
    Resizes the bit array to \a size bits.

    If \a size is greater than the current size, the bit array is
    extended to make it \a size bits with the extra bits added to the
    end. The new bits are initialized to false (0).

    If \a size is less than the current size, bits are removed from
    the end.

    \sa size()
*/
void QBitArray::resize(int size)
{
    if (!size) {
        d.resize(0);
    } else {
        int s = d.size();
        d.resize(1 + (size+7)/8);
        uchar* c = reinterpret_cast<uchar*>(d.data());
        if (size > (s << 3))
            memset(c + s, 0, d.size() - s);
        *c = d.size()*8 - size;
    }
}

/*! \fn bool QBitArray::isEmpty() const

    Returns true if this bit array has size 0; otherwise returns
    false.

    \sa size()
*/

/*! \fn bool QBitArray::isNull() const

    Returns true if this bit array is null; otherwise returns false.

    Example:
    \code
        QBitArray().isNull();           // returns true
        QBitArray(0).isNull();          // returns false
        QBitArray(3).isNull();          // returns false
    \endcode

    Qt makes a distinction between null bit arrays and empty bit
    arrays for historical reasons. For most applications, what
    matters is whether or not a bit array contains any data,
    and this can be determined using isEmpty().

    \sa isEmpty()
*/

/*! \fn bool QBitArray::fill(bool value, int size = -1)

    Sets every bit in the bit array to \a value, returning true if successful;
    otherwise returns false. If \a size is different from -1 (the default),
    the bit array is resized to \a size beforehand.

    Example:
    \code
        QBitArray ba(8);
        ba.fill(true);
        // ba: [ 1, 1, 1, 1, 1, 1, 1, 1 ]

        ba.fill(false, 2);
        // ba: [ 0, 0 ]
    \endcode

    \sa resize()
*/

/*!
    \overload

    Sets bits at index positions \a begin up to and excluding \a end
    to \a value.

    \a begin and \a end must be a valid index position in the bit
    array (i.e., 0 <= \a begin <= size() and 0 <= \a end <= size()).
*/

void QBitArray::fill(bool value, int begin, int end)
{
    while (begin < end && begin & 0x7)
        setBit(begin++, value);
    int len = end - begin;
    if (len <= 0)
        return;
    int s = len & ~0x7;
    uchar *c = reinterpret_cast<uchar*>(d.data());
    memset(c + (begin >> 3) + 1, value ? 0xff : 0, s >> 3);
    begin += s;
    while (begin < end)
        setBit(begin++, value);
}

/*! \fn bool QBitArray::isDetached() const

    \internal
*/

/*! \fn void QBitArray::detach()

    \internal
*/

/*! \fn void QBitArray::clear()

    Clears the contents of the bit array and makes it empty.

    \sa resize(), isEmpty()
*/

/*! \fn void QBitArray::truncate(int pos)

    Truncates the bit array at index position \a pos.

    If \a pos is beyond the end of the array, nothing happens.

    \sa resize()
*/

/*! \fn bool QBitArray::toggleBit(int i)

    Inverts the value of the bit at index position \a i, returning the
    previous value of that bit as either true (if it was set) or false (if
    it was unset).

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

    \a i must be a valid index position in the bit array (i.e., 0 <=
    \a i < size()).

    \sa setBit(), clearBit()
*/

/*! \fn bool QBitArray::testBit(int i) const

    Returns true if the bit at index position \a i is 1; otherwise
    returns false.

    \a i must be a valid index position in the bit array (i.e., 0 <=
    \a i < size()).

    \sa setBit(), clearBit()
*/

/*! \fn bool QBitArray::setBit(int i)

    Sets the bit at index position \a i to 1.

    \a i must be a valid index position in the bit array (i.e., 0 <=
    \a i < size()).

    \sa clearBit(), toggleBit()
*/

/*! \fn void QBitArray::setBit(int i, bool value)

    \overload

    Sets the bit at index position \a i to \a value.
*/

/*! \fn void QBitArray::clearBit(int i)

    Sets the bit at index position \a i to 0.

    \a i must be a valid index position in the bit array (i.e., 0 <=
    \a i < size()).

    \sa setBit(), toggleBit()
*/

/*! \fn bool QBitArray::at(int i) const

    Returns the value of the bit at index position \a i.

    \a i must be a valid index position in the bit array (i.e., 0 <=
    \a i < size()).

    \sa operator[]()
*/

/*! \fn QBitRef QBitArray::operator[](int i)

    Returns the bit at index position \a i as a modifiable reference.

    \a i must be a valid index position in the bit array (i.e., 0 <=
    \a i < size()).