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package sun.jvm.hotspot.utilities;

A BitMap implementing the BitMapInterface.
/** A BitMap implementing the BitMapInterface. */
public class BitMapSegmented implements BitMapInterface { private static final int SegmentSizeBits = 30; private static final int SegmentSize = 1 << (SegmentSizeBits - 1); public BitMapSegmented(long sizeInBits) { this.size = sizeInBits; if (sizeInBits == 0) { segmentBitMaps = new BitMap[0]; return; } int lastSegmentSize = (int)(sizeInBits % SegmentSize); int segments = segmentIndex(sizeInBits - 1) + 1; int completeSegments = segments - ((lastSegmentSize != 0) ? 1 : 0); segmentBitMaps = new BitMap[segments]; for (int i = 0; i < completeSegments; i++) { segmentBitMaps[i] = new BitMap(SegmentSize); } if (lastSegmentSize != 0) { segmentBitMaps[completeSegments] = new BitMap(lastSegmentSize); } } public long size() { return size; } // Accessors public boolean at(long offset) { assert offset < size; int segmentIndex = segmentIndex(offset); int segmentOffset = segmentOffset(offset); return segmentBitMaps[segmentIndex].at(segmentOffset); } public void atPut(long offset, boolean value) { assert offset < size; int segmentIndex = segmentIndex(offset); int segmentOffset = segmentOffset(offset); segmentBitMaps[segmentIndex].atPut(segmentOffset, value); } public void clear() { for (BitMap map : segmentBitMaps) { map.clear(); } } //---------------------------------------------------------------------- // Internals only below this point // private final long size; // in bits private final BitMap[] segmentBitMaps; private int segmentIndex(long offset) { long longIndex = offset / SegmentSize; assert longIndex < Integer.MAX_VALUE; return (int)longIndex; } private int segmentOffset(long offset) { return (int)(offset % SegmentSize); } }