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/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
package com.badlogic.gdx.utils;
import java.util.Arrays;
/** A bitset, without size limitation, allows comparison via bitwise operators to other bitfields.
*
* @author mzechner
* @author jshapcott */
public class Bits {
long[] bits = {0};
public Bits () {
}
/** Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range 0 through
* nbits-1.
* @param nbits the initial size of the bit set */
public Bits (int nbits) {
checkCapacity(nbits >>> 6);
}
/** Creates a bit set from another bit set
* @param bitsToCpy bitset to cpy */
public Bits (Bits bitsToCpy) {
this.bits = new long[bitsToCpy.bits.length];
System.arraycopy(bitsToCpy.bits, 0, this.bits, 0, bitsToCpy.bits.length);
}
/** @param index the index of the bit
* @return whether the bit is set
* @throws ArrayIndexOutOfBoundsException if index < 0 */
public boolean get (int index) {
final int word = index >>> 6;
if (word >= bits.length) return false;
return (bits[word] & (1L << (index & 0x3F))) != 0L;
}
/** Returns the bit at the given index and clears it in one go.
* @param index the index of the bit
* @return whether the bit was set before invocation
* @throws ArrayIndexOutOfBoundsException if index < 0 */
public boolean getAndClear (int index) {
final int word = index >>> 6;
if (word >= bits.length) return false;
long oldBits = bits[word];
bits[word] &= ~(1L << (index & 0x3F));
return bits[word] != oldBits;
}
/** Returns the bit at the given index and sets it in one go.
* @param index the index of the bit
* @return whether the bit was set before invocation
* @throws ArrayIndexOutOfBoundsException if index < 0 */
public boolean getAndSet (int index) {
final int word = index >>> 6;
checkCapacity(word);
long oldBits = bits[word];
bits[word] |= 1L << (index & 0x3F);
return bits[word] == oldBits;
}
/** @param index the index of the bit to set
* @throws ArrayIndexOutOfBoundsException if index < 0 */
public void set (int index) {
final int word = index >>> 6;
checkCapacity(word);
bits[word] |= 1L << (index & 0x3F);
}
/** @param index the index of the bit to flip */
public void flip (int index) {
final int word = index >>> 6;
checkCapacity(word);
bits[word] ^= 1L << (index & 0x3F);
}
private void checkCapacity (int len) {
if (len >= bits.length) {
long[] newBits = new long[len + 1];
System.arraycopy(bits, 0, newBits, 0, bits.length);
bits = newBits;
}
}
/** @param index the index of the bit to clear
* @throws ArrayIndexOutOfBoundsException if index < 0 */
public void clear (int index) {
final int word = index >>> 6;
if (word >= bits.length) return;
bits[word] &= ~(1L << (index & 0x3F));
}
/** Clears the entire bitset */
public void clear () {
Arrays.fill(bits, 0);
}
/** @return the number of bits currently stored, not the highset set bit! */
public int numBits () {
return bits.length << 6;
}
/** Returns the "logical size" of this bitset: the index of the highest set bit in the bitset plus one. Returns zero if the
* bitset contains no set bits.
*
* @return the logical size of this bitset */
public int length () {
long[] bits = this.bits;
for (int word = bits.length - 1; word >= 0; --word) {
long bitsAtWord = bits[word];
if (bitsAtWord != 0) {
for (int bit = 63; bit >= 0; --bit) {
if ((bitsAtWord & (1L << (bit & 0x3F))) != 0L) {
return (word << 6) + bit + 1;
}
}
}
}
return 0;
}
/** @return true if this bitset contains at least one bit set to true */
public boolean notEmpty () {
return !isEmpty();
}
/** @return true if this bitset contains no bits that are set to true */
public boolean isEmpty () {
long[] bits = this.bits;
int length = bits.length;
for (int i = 0; i < length; i++) {
if (bits[i] != 0L) {
return false;
}
}
return true;
}
/** Returns the index of the first bit that is set to true that occurs on or after the specified starting index. If no such bit
* exists then -1 is returned. */
public int nextSetBit (int fromIndex) {
long[] bits = this.bits;
int word = fromIndex >>> 6;
int bitsLength = bits.length;
if (word >= bitsLength) return -1;
long bitsAtWord = bits[word];
if (bitsAtWord != 0) {
for (int i = fromIndex & 0x3f; i < 64; i++) {
if ((bitsAtWord & (1L << (i & 0x3F))) != 0L) {
return (word << 6) + i;
}
}
}
for (word++; word < bitsLength; word++) {
if (word != 0) {
bitsAtWord = bits[word];
if (bitsAtWord != 0) {
for (int i = 0; i < 64; i++) {
if ((bitsAtWord & (1L << (i & 0x3F))) != 0L) {
return (word << 6) + i;
}
}
}
}
}
return -1;
}
/** Returns the index of the first bit that is set to false that occurs on or after the specified starting index. */
public int nextClearBit (int fromIndex) {
long[] bits = this.bits;
int word = fromIndex >>> 6;
int bitsLength = bits.length;
if (word >= bitsLength) return bits.length << 6;
long bitsAtWord = bits[word];
for (int i = fromIndex & 0x3f; i < 64; i++) {
if ((bitsAtWord & (1L << (i & 0x3F))) == 0L) {
return (word << 6) + i;
}
}
for (word++; word < bitsLength; word++) {
if (word == 0) {
return word << 6;
}
bitsAtWord = bits[word];
for (int i = 0; i < 64; i++) {
if ((bitsAtWord & (1L << (i & 0x3F))) == 0L) {
return (word << 6) + i;
}
}
}
return bits.length << 6;
}
/** Performs a logical AND of this target bit set with the argument bit set. This bit set is modified so that each bit
* in it has the value true if and only if it both initially had the value true and the corresponding bit in the bit set
* argument also had the value true.
* @param other a bit set */
public void and (Bits other) {
int commonWords = Math.min(bits.length, other.bits.length);
for (int i = 0; commonWords > i; i++) {
bits[i] &= other.bits[i];
}
if (bits.length > commonWords) {
for (int i = commonWords, s = bits.length; s > i; i++) {
bits[i] = 0L;
}
}
}
/** Clears all of the bits in this bit set whose corresponding bit is set in the specified bit set.
*
* @param other a bit set */
public void andNot (Bits other) {
for (int i = 0, j = bits.length, k = other.bits.length; i < j && i < k; i++) {
bits[i] &= ~other.bits[i];
}
}
/** Performs a logical OR of this bit set with the bit set argument. This bit set is modified so that a bit in it has
* the value true if and only if it either already had the value true or the corresponding bit in the bit set argument has the
* value true.
* @param other a bit set */
public void or (Bits other) {
int commonWords = Math.min(bits.length, other.bits.length);
for (int i = 0; commonWords > i; i++) {
bits[i] |= other.bits[i];
}
if (commonWords < other.bits.length) {
checkCapacity(other.bits.length);
for (int i = commonWords, s = other.bits.length; s > i; i++) {
bits[i] = other.bits[i];
}
}
}
/** Performs a logical XOR of this bit set with the bit set argument. This bit set is modified so that a bit in it has
* the value true if and only if one of the following statements holds:
*
* - The bit initially has the value true, and the corresponding bit in the argument has the value false.
* - The bit initially has the value false, and the corresponding bit in the argument has the value true.
*
* @param other */
public void xor (Bits other) {
int commonWords = Math.min(bits.length, other.bits.length);
for (int i = 0; commonWords > i; i++) {
bits[i] ^= other.bits[i];
}
if (commonWords < other.bits.length) {
checkCapacity(other.bits.length);
for (int i = commonWords, s = other.bits.length; s > i; i++) {
bits[i] = other.bits[i];
}
}
}
/** Returns true if the specified BitSet has any bits set to true that are also set to true in this BitSet.
*
* @param other a bit set
* @return boolean indicating whether this bit set intersects the specified bit set */
public boolean intersects (Bits other) {
long[] bits = this.bits;
long[] otherBits = other.bits;
for (int i = Math.min(bits.length, otherBits.length) - 1; i >= 0; i--) {
if ((bits[i] & otherBits[i]) != 0) {
return true;
}
}
return false;
}
/** Returns true if this bit set is a super set of the specified set, i.e. it has all bits set to true that are also set to
* true in the specified BitSet.
*
* @param other a bit set
* @return boolean indicating whether this bit set is a super set of the specified set */
public boolean containsAll (Bits other) {
long[] bits = this.bits;
long[] otherBits = other.bits;
int otherBitsLength = otherBits.length;
int bitsLength = bits.length;
for (int i = bitsLength; i < otherBitsLength; i++) {
if (otherBits[i] != 0) {
return false;
}
}
for (int i = Math.min(bitsLength, otherBitsLength) - 1; i >= 0; i--) {
if ((bits[i] & otherBits[i]) != otherBits[i]) {
return false;
}
}
return true;
}
@Override
public int hashCode () {
final int word = length() >>> 6;
int hash = 0;
for (int i = 0; word >= i; i++) {
hash = 127 * hash + (int)(bits[i] ^ (bits[i] >>> 32));
}
return hash;
}
@Override
public boolean equals (Object obj) {
if (this == obj) return true;
if (obj == null) return false;
if (getClass() != obj.getClass()) return false;
Bits other = (Bits)obj;
long[] otherBits = other.bits;
int commonWords = Math.min(bits.length, otherBits.length);
for (int i = 0; commonWords > i; i++) {
if (bits[i] != otherBits[i]) return false;
}
if (bits.length == otherBits.length) return true;
return length() == other.length();
}
}