Package com.jogamp.common.util

Class Bitfield.Util

java.lang.Object

com.jogamp.common.util.Bitfield.Util

Enclosing interface:

Bitfield

public static class Bitfield.Util
extends Object

Bit operation utilities (static).

Field Summary

Fields

Modifier and Type	Field	Description
static int	MAX_POWER_OF_2	Maximum 32bit integer value being of isPowerOf2(int).

Constructor Summary

Constructors

Constructor	Description
Util()

Method Summary

Modifier and Type	Method	Description
static int	bitCount(int n)	Returns the number of set bits within given 32bit integer in O(1) using a HAKEM 169 Bit Count inspired implementation:
static int	getBitMask(int n)	Returns the 32 bit mask of n-bits, i.e.
static boolean	isPowerOf2(int n)	Returns true if the given integer is a power of 2
static int	nextPowerOf2(int n)	Returns the next higher power of 2 of 32-bit of given n
static int	roundToPowerOf2(int n)	If the given n is not isPowerOf2(int) return nextPowerOf2(int), otherwise return n unchanged.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_POWER_OF_2

public static final int MAX_POWER_OF_2

Maximum 32bit integer value being of isPowerOf2(int).

We rely on the JVM spec Integer.SIZE == 32.

See Also:

Constant Field Values

Constructor Detail

Util

public Util()

Method Detail

getBitMask

public static int getBitMask(int n)

Returns the 32 bit mask of n-bits, i.e. n low order 1’s.

Implementation handles n == 32.

Throws:

IndexOutOfBoundsException - if b is out of bounds, i.e. > 32

bitCount

public static final int bitCount(int n)

Returns the number of set bits within given 32bit integer in O(1) using a HAKEM 169 Bit Count inspired implementation:

   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/
   http://www.hackersdelight.org/
 

We rely on the JVM spec Integer.SIZE == 32.

isPowerOf2

public static final boolean isPowerOf2(int n)

Returns true if the given integer is a power of 2

Source: bithacks: http://www.graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2

nextPowerOf2

public static final int nextPowerOf2(int n)

Returns the next higher power of 2 of 32-bit of given n

Source: bithacks: http://www.graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2

We rely on the JVM spec Integer.SIZE == 32.

roundToPowerOf2

public static final int roundToPowerOf2(int n)

If the given n is not isPowerOf2(int) return nextPowerOf2(int), otherwise return n unchanged.

 return isPowerOf2(n) ? n : nextPowerOf2(n);
 

We rely on the JVM spec Integer.SIZE == 32.