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/*
* Copyright (C) 2012, Google Inc.
* and other copyright owners as documented in the project's IP log.
*
* This program and the accompanying materials are made available
* under the terms of the Eclipse Distribution License v1.0 which
* accompanies this distribution, is reproduced below, and is
* available at http://www.eclipse.org/org/documents/edl-v10.php
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* - Neither the name of the Eclipse Foundation, Inc. nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.eclipse.jgit.storage.file;
import java.util.Arrays;
import javaewah.EWAHCompressedBitmap;
/**
* A random access BitSet to supports efficient conversions to
* EWAHCompressedBitmap.
*/
final class BitSet {
private long[] words;
BitSet(int initialCapacity) {
words = new long[block(initialCapacity) + 1];
}
final void clear() {
Arrays.fill(words, 0);
}
final void set(int position) {
int block = block(position);
if (block >= words.length) {
long[] buf = new long[2 * block(position)];
System.arraycopy(words, 0, buf, 0, words.length);
words = buf;
}
words[block] |= mask(position);
}
final void clear(int position) {
int block = block(position);
if (block < words.length)
words[block] &= ~mask(position);
}
final boolean get(int position) {
int block = block(position);
return block < words.length && (words[block] & mask(position)) != 0;
}
final EWAHCompressedBitmap toEWAHCompressedBitmap() {
EWAHCompressedBitmap compressed = new EWAHCompressedBitmap(
words.length);
int runningEmptyWords = 0;
long lastNonEmptyWord = 0;
for (long word : words) {
if (word == 0) {
runningEmptyWords++;
continue;
}
if (lastNonEmptyWord != 0)
compressed.add(lastNonEmptyWord);
if (runningEmptyWords > 0) {
compressed.addStreamOfEmptyWords(false, runningEmptyWords);
runningEmptyWords = 0;
}
lastNonEmptyWord = word;
}
int bitsThatMatter = 64 - Long.numberOfLeadingZeros(lastNonEmptyWord);
if (bitsThatMatter > 0)
compressed.add(lastNonEmptyWord, bitsThatMatter);
return compressed;
}
private static final int block(int position) {
return position >> 6;
}
private static final long mask(int position) {
return 1L << position;
}
}
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