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/**
* Copyright 2015 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 interface for efficient storage access in O(1).
*/
public interface Bitfield {
/**
* Bit operation utilities (static).
*/
public static class Util {
/**
* 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;
}
}
/**
* Simple {@link Bitfield} factory for returning the efficient implementation.
*/
public static class Factory {
/**
* Creates am efficient {@link Bitfield} instance based on the requested {@code storageBitSize}.
* <p>
* Implementation returns a plain 32 bit integer field implementation for
* {@code storageBitSize} ≤ 32 bits or an 32 bit integer array implementation otherwise.
* </p>
*/
public static Bitfield create(final int storageBitSize) {
if( 32 >= storageBitSize ) {
return new jogamp.common.util.Int32Bitfield();
} else {
return new jogamp.common.util.Int32ArrayBitfield(storageBitSize);
}
}
}
/**
* Returns the storage size in bit units, e.g. 32 bit for implementations using one {@code int} field.
*/
int getStorageBitSize();
/**
* Returns the 32 bit integer mask w/ its lowest bit at the bit number {@code rightBitnum}.
* @param rightBitnum bit number denoting the position of the lowest bit, restricted to [0..{@link #getStorageBitSize()}-32].
* @throws ArrayIndexOutOfBoundsException if {@code rightBitnum} is out of bounds
*/
int getInt32(final int rightBitnum) throws ArrayIndexOutOfBoundsException;
/**
* Sets the given 32 bit integer mask w/ its lowest bit at the bit number {@code rightBitnum}.
* @param rightBitnum bit number denoting the position of the lowest bit, restricted to [0..{@link #getStorageBitSize()}-32].
* @param mask denoting the 32 bit mask value to store
* @throws ArrayIndexOutOfBoundsException if {@code rightBitnum} is out of bounds
*/
void putInt32(final int rightBitnum, final int mask) throws ArrayIndexOutOfBoundsException;
/**
* Return <code>true</code> if the bit at position <code>bitnum</code> is set, otherwise <code>false</code>.
* @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1].
* @throws ArrayIndexOutOfBoundsException if {@code bitnum} is out of bounds
*/
boolean get(final int bitnum) throws ArrayIndexOutOfBoundsException;
/**
* Set or clear the bit at position <code>bitnum</code> according to <code>bit</code>
* and return the previous value.
* @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1].
* @throws ArrayIndexOutOfBoundsException if {@code bitnum} is out of bounds
*/
boolean put(final int bitnum, final boolean bit) throws ArrayIndexOutOfBoundsException;
/**
* Set the bit at position <code>bitnum</code> according to <code>bit</code>.
* @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1].
* @throws ArrayIndexOutOfBoundsException if {@code bitnum} is out of bounds
*/
void set(final int bitnum) throws ArrayIndexOutOfBoundsException;
/**
* Clear the bit at position <code>bitnum</code> according to <code>bit</code>.
* @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1].
* @throws ArrayIndexOutOfBoundsException if {@code bitnum} is out of bounds
*/
void clear(final int bitnum) throws ArrayIndexOutOfBoundsException;
/**
* Returns the number of set bits within this bitfield.
* <p>
* Utilizes {#link {@link Bitfield.Util#getBitCount(int)}}.
* </p>
*/
int getBitCount();
}
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