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/*
* Copyright (C) 2010 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifndef Bitmap_h
#define Bitmap_h
#include "FixedArray.h"
#include "StdLibExtras.h"
#include <stdint.h>
namespace WTF {
template<size_t size>
class Bitmap {
private:
typedef uint32_t WordType;
public:
Bitmap();
bool get(size_t) const;
void set(size_t);
void clear(size_t);
void clearAll();
void advanceToNextFreeBit(size_t&) const;
size_t count(size_t = 0) const;
size_t isEmpty() const;
size_t isFull() const;
private:
static const WordType wordSize = sizeof(WordType) * 8;
static const WordType words = (size + wordSize - 1) / wordSize;
// the literal '1' is of type signed int. We want to use an unsigned
// version of the correct size when doing the calculations because if
// WordType is larger than int, '1 << 31' will first be sign extended
// and then casted to unsigned, meaning that set(31) when WordType is
// a 64 bit unsigned int would give 0xffff8000
static const WordType one = 1;
FixedArray<WordType, words> bits;
};
template<size_t size>
inline Bitmap<size>::Bitmap()
{
clearAll();
}
template<size_t size>
inline bool Bitmap<size>::get(size_t n) const
{
return !!(bits[n / wordSize] & (one << (n % wordSize)));
}
template<size_t size>
inline void Bitmap<size>::set(size_t n)
{
bits[n / wordSize] |= (one << (n % wordSize));
}
template<size_t size>
inline void Bitmap<size>::clear(size_t n)
{
bits[n / wordSize] &= ~(one << (n % wordSize));
}
template<size_t size>
inline void Bitmap<size>::clearAll()
{
memset(bits.data(), 0, sizeof(bits));
}
template<size_t size>
inline void Bitmap<size>::advanceToNextFreeBit(size_t& start) const
{
if (!~bits[start / wordSize])
start = ((start / wordSize) + 1) * wordSize;
else
++start;
}
template<size_t size>
inline size_t Bitmap<size>::count(size_t start) const
{
size_t result = 0;
for ( ; (start % wordSize); ++start) {
if (get(start))
++result;
}
for (size_t i = start / wordSize; i < words; ++i)
result += WTF::bitCount(bits[i]);
return result;
}
template<size_t size>
inline size_t Bitmap<size>::isEmpty() const
{
for (size_t i = 0; i < words; ++i)
if (bits[i])
return false;
return true;
}
template<size_t size>
inline size_t Bitmap<size>::isFull() const
{
for (size_t i = 0; i < words; ++i)
if (~bits[i])
return false;
return true;
}
}
#endif
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