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/**
* Copyright 2012 JogAmp Community. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are
* permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
*
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY JogAmp Community ``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 JogAmp Community 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.
*
* The views and conclusions contained in the software and documentation are those of the
* authors and should not be interpreted as representing official policies, either expressed
* or implied, of JogAmp Community.
*/
package com.jogamp.common.util;
/**
* Simple bitfield holder class using an int[] storage.
* <p>
* IntBitfield allows convenient access of a wide field of transient bits using efficient storage in O(1).
* </p>
* <p>
* It can be used e.g. to map key-codes to pressed-state etc.
* </p>
*/
public class IntBitfield {
/** Unit size in bits, here 32 bits for one int unit. */
public static final int UNIT_SIZE = 32;
private static final long UNIT_SHIFT_L = 5L;
private static final int UNIT_SHIFT_I = 5;
private final int[] storage;
private final long bitsCountL;
private final int bitsCountI;
/**
* @param bitCount
*/
public IntBitfield(long bitCount) {
final int units = (int) Math.max(1L, ( bitCount + 7L ) >>> UNIT_SHIFT_L);
this.storage = new int[units];
this.bitsCountL = (long)units << UNIT_SHIFT_L ;
this.bitsCountI = bitsCountL > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int)bitsCountL;
}
/**
* @param bitCount
*/
public IntBitfield(int bitCount) {
final int units = Math.max(1, ( bitCount + 7 ) >>> UNIT_SHIFT_I);
this.storage = new int[units];
this.bitsCountI = units << UNIT_SHIFT_I;
this.bitsCountL = bitsCountI;
}
private final void check(long bitnum) {
if( 0 > bitnum || bitnum >= bitsCountL ) {
throw new ArrayIndexOutOfBoundsException("Bitnum should be within [0.."+(bitsCountL-1)+"], but is "+bitnum);
}
}
private final void check(int bitnum) {
if( 0 > bitnum || bitnum >= bitsCountI ) {
throw new ArrayIndexOutOfBoundsException("Bitnum should be within [0.."+(bitsCountI-1)+"], but is "+bitnum);
}
}
/** Return the capacity of this bit field, i.e. the number of bits stored int this field. */
public final long capacity() { return bitsCountL; }
/** Return <code>true</code> if the bit at position <code>bitnum</code> is set, otherwise <code>false</code>. */
public final boolean get(long bitnum) {
check(bitnum);
final int u = (int) ( bitnum >>> UNIT_SHIFT_L );
final int b = (int) ( bitnum - ( (long)u << UNIT_SHIFT_L ) );
return 0 != ( storage[u] & ( 1 << b ) ) ;
}
/** Return <code>true</code> if the bit at position <code>bitnum</code> is set, otherwise <code>false</code>. */
public final boolean get(int bitnum) {
check(bitnum);
final int u = bitnum >>> UNIT_SHIFT_I;
final int b = bitnum - ( u << UNIT_SHIFT_I );
return 0 != ( storage[u] & ( 1 << b ) ) ;
}
/**
* Set or clear the bit at position <code>bitnum</code> according to <code>bit</code>
* and return the previous value.
*/
public final boolean put(long bitnum, boolean bit) {
check(bitnum);
final int u = (int) ( bitnum >>> UNIT_SHIFT_L );
final int b = (int) ( bitnum - ( (long)u << UNIT_SHIFT_L ) );
final int m = 1 << b;
final boolean prev = 0 != ( storage[u] & m ) ;
if( prev != bit ) {
if( bit ) {
storage[u] |= m;
} else {
storage[u] &= ~m;
}
}
return prev;
}
/**
* Set or clear the bit at position <code>bitnum</code> according to <code>bit</code>
* and return the previous value.
*/
public final boolean put(int bitnum, boolean bit) {
check(bitnum);
final int u = bitnum >>> UNIT_SHIFT_I;
final int b = bitnum - ( u << UNIT_SHIFT_I );
final int m = 1 << b;
final boolean prev = 0 != ( storage[u] & m ) ;
if( prev != bit ) {
if( bit ) {
storage[u] |= m;
} else {
storage[u] &= ~m;
}
}
return prev;
}
/**
* Returns the number of set bits within given 32bit integer in O(1)
* using <i>HAKEM Bit Count</i>:
* <pre>
* http://www.inwap.com/pdp10/hbaker/hakmem/hakmem.html
* http://home.pipeline.com/~hbaker1/hakmem/hacks.html#item169
* http://tekpool.wordpress.com/category/bit-count/
* </pre>
*/
public static final int getBitCount(final int n) {
// Note: Original used 'unsigned int',
// hence we use the unsigned right-shift '>>>'
int c = n;
c -= (n >>> 1) & 033333333333;
c -= (n >>> 2) & 011111111111;
return ( (c + ( c >>> 3 ) ) & 030707070707 ) % 63;
}
/**
* Returns the number of set bits within this bitfield.
* <p>
* Utilizes {#link {@link #getBitCount(int)}}.
* </p>
*/
public long getBitCount() {
long c = 0;
for(int i = storage.length-1; i>=0; i--) {
c += getBitCount(storage[i]);
}
return c;
}
}
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