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/*
Title: Bitmap. Generally used by the garbage collector to indicate allocated words
Copyright (c) 2006 David C.J. Matthews
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 2.1 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 St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef BITMAP_H_DEFINED
#define BITMAP_H_DEFINED
#include "globals.h" // For POLYUNSIGNED
/* bitmaps using arrays of word */
#define BITS_PER_BYTE 8
#define BITS_PER_WORD (BITS_PER_BYTE * sizeof(POLYUNSIGNED))
class Bitmap
{
public:
Bitmap(): m_bits(0) {}
Bitmap(POLYUNSIGNED bits);
~Bitmap();
bool Create(POLYUNSIGNED bits);
private:
static POLYUNSIGNED BitN(POLYUNSIGNED n) { return (POLYUNSIGNED)1 << (n & (BITS_PER_WORD-1)); }
public:
// Set a single bit
void SetBit(POLYUNSIGNED n) { m_bits[n/BITS_PER_WORD] |= BitN(n); }
// Set a range of bits
void SetBits(POLYUNSIGNED bitno, POLYUNSIGNED length);
// Clear a bit
void ClearBit(POLYUNSIGNED n) { m_bits[n/BITS_PER_WORD] &= ~BitN(n); }
// Clear a range of bits. May already be partly clear
void ClearBits(POLYUNSIGNED bitno, POLYUNSIGNED length);
// Test a bit
bool TestBit(POLYUNSIGNED n) const { return (m_bits[n/BITS_PER_WORD] & BitN(n)) != 0; }
// How many zero bits (maximum n) are there in the bitmap, starting at location start?
POLYUNSIGNED CountZeroBits(POLYUNSIGNED bitno, POLYUNSIGNED n);
//* search the bitmap from the high end down looking for n contiguous zeros
POLYUNSIGNED FindFree(POLYUNSIGNED limit, POLYUNSIGNED bitno, POLYUNSIGNED n);
private:
POLYUNSIGNED *m_bits;
};
#endif
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