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usage_bits.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2002-2004 The ScummVM project
 *
 * 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.
 *
 * $Header: /cvsroot/scummvm/scummvm/scumm/usage_bits.cpp,v 1.12 2004/01/06 12:45:31 fingolfin Exp $
 *
 */

#include "stdafx.h"
#include "scumm/scumm.h"
#include "scumm/usage_bits.h"

namespace Scumm {

void ScummEngine::upgradeGfxUsageBits() {
      int i;

      for (i = 409; i >= 0; i--) {
            bool dirty_bit = ((gfxUsageBits[i] & 0x80000000) != 0);
            bool restored_bit = ((gfxUsageBits[i] & 0x40000000) != 0);
            
            gfxUsageBits[3 * i] = gfxUsageBits[i] & 0x3FFFFFFF;
            if (dirty_bit)
                  setGfxUsageBit(i, USAGE_BIT_DIRTY);
            if (restored_bit)
                  setGfxUsageBit(i, USAGE_BIT_RESTORED);
      }
}

void ScummEngine::setGfxUsageBit(int strip, int bit) {
      assert(1 <= bit && bit <= 96);
      bit--;
      gfxUsageBits[3 * strip + bit / 32] |= (1 << (bit % 32));
}

void ScummEngine::clearGfxUsageBit(int strip, int bit) {
      assert(1 <= bit && bit <= 96);
      bit--;
      gfxUsageBits[3 * strip + bit / 32] &= ~(1 << (bit % 32));
}

bool ScummEngine::testGfxUsageBit(int strip, int bit) {
      assert(1 <= bit && bit <= 96);
      bit--;
      return (gfxUsageBits[3 * strip + bit / 32] & (1 << (bit % 32))) != 0;
}

bool ScummEngine::testGfxAnyUsageBits(int strip) {
      // Exclude the DIRTY and RESTORED bits from the test
      uint32 bitmask[3] = { 0xFFFFFFFF, 0xFFFFFFFF, 0x3FFFFFFF };
      int i;

      for (i = 0; i < 3; i++)
            if (gfxUsageBits[3 * strip + i] & bitmask[i])
                  return true;

      return false;
}

bool ScummEngine::testGfxOtherUsageBits(int strip, int bit) {
      // Don't exclude the DIRTY and RESTORED bits from the test
      uint32 bitmask[3] = { 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
      int i;

      assert(1 <= bit && bit <= 96);
      bit--;
      bitmask[bit / 32] &= ~(1 << (bit % 32));

      for (i = 0; i < 3; i++)
            if (gfxUsageBits[3 * strip + i] & bitmask[i])
                  return true;

      return false;
}

} // End of namespace Scumm

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