BitSet.cpp

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/*
Copyright (C) 2003  The Pentagram Team

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

#include "pent_include.h"
#include "BitSet.h"

#include "IDataSource.h"
#include "ODataSource.h"

BitSet::BitSet() : size(0), bytes(0), data(0)
{

}


BitSet::BitSet(unsigned int size_)
{
        data = 0;
        setSize(size_);
}

BitSet::~BitSet()
{
        delete[] data;
}

void BitSet::setSize(unsigned int size_)
{
        if (data) delete[] data;

        size = size_;
        bytes = 0;
        bytes = size / 8;
        if (size % 8 != 0) bytes++;

        data = new uint8[bytes];
        for (unsigned int i = 0; i < bytes; ++i)
                data[i] = 0;
}

uint32 BitSet::getBits(unsigned int pos, unsigned int n)
{
        assert(n <= 32);
        assert(pos + n <= size);
        if (n == 0) return 0;

        unsigned int firstbyte = pos / 8;
        unsigned int lastbyte = (pos + n - 1) / 8;

        if (firstbyte == lastbyte) {
                return ((data[firstbyte] >> (pos % 8)) & ((1 << n) - 1));
        }

        unsigned int firstbits = 8 - (pos % 8);
        unsigned int lastbits = ((pos + n - 1) % 8) + 1;

        unsigned int firstmask = ((1 << firstbits) - 1) << (8 - firstbits);
        unsigned int lastmask = ((1 << lastbits) - 1);

        uint32 ret = 0;

        ret |= (data[firstbyte] & firstmask) >> (8 - firstbits);
        unsigned int shift = firstbits;
        for (unsigned int i = firstbyte + 1; i < lastbyte; ++i) {
                ret |= (data[i] << shift);
                shift += 8;
        }
        ret |= (data[lastbyte] & lastmask) << shift;

        return ret;
}

void BitSet::setBits(unsigned int pos, unsigned int n, uint32 bits)
{
        assert(n <= 32);
        assert(pos + n <= size);
        if (n == 0) return;

        unsigned int firstbyte = pos / 8;
        unsigned int lastbyte = (pos + n - 1) / 8;

        if (firstbyte == lastbyte) {
                data[firstbyte] &= ~(((1 << n) - 1) << (pos % 8));
                data[firstbyte] |= (bits & ((1 << n) - 1)) << (pos % 8);
                return;
        }

        unsigned int firstbits = 8 - (pos % 8);
        unsigned int lastbits = ((pos + n - 1) % 8) + 1;

        unsigned int firstmask = ((1 << firstbits) - 1) << (8 - firstbits);
        unsigned int lastmask = ((1 << lastbits) - 1);

        data[firstbyte] &= ~firstmask;
        data[firstbyte] |= (bits << (8 - firstbits)) & firstmask;
        unsigned int shift = firstbits;
        for (unsigned int i = firstbyte + 1; i < lastbyte; ++i) {
                data[i] = (bits >> shift);
                shift += 8;
        }
        data[lastbyte] &= ~lastmask;
        data[lastbyte] |= (bits >> shift) & lastmask;
}

void BitSet::save(ODataSource* ods)
{
        ods->write4(size);
        ods->write(data, bytes);
}

bool BitSet::load(IDataSource* ids, uint32 version)
{
        uint32 s = ids->read4();
        setSize(s);
        ids->read(data, bytes);

        return true;
}

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