com.hazelcast.util

Class QuickMath

java.lang.Object

com.hazelcast.util.QuickMath

public final class QuickMath
extends Object

The class QuickMath contains methods to perform optimized mathematical operations. Methods are allowed to put additional constraints on the range of input values if required for efficiency. Methods are not required to perform validation of input arguments, but they have to indicate the constraints in theirs contract.

Method Summary

Modifier and Type	Method and Description
static String	bytesToHex(byte[] in)
static int	compareIntegers(int i1, int i2) Compares two integers
static int	compareLongs(long l1, long l2) Compares two longs
static int	divideByAndCeilToInt(double d, int k) Divide d by k and return the smallest integer greater than or equal to the result.
static long	divideByAndCeilToLong(double d, int k) Divide d by k and return the smallest integer greater than or equal to the result.
static int	divideByAndRoundToInt(double d, int k) Divide d by k and return the int value closest to the result.
static long	divideByAndRoundToLong(double d, int k) Divide d by k and return the long value closest to the result.
static boolean	isPowerOfTwo(long x) Return true if input argument is power of two.
static int	log2(int value) Return the log 2 result for this int.
static int	log2(long value) Return the log 2 result for this long.
static int	modPowerOfTwo(int a, int b) Computes the remainder of the division of a by b.
static long	modPowerOfTwo(long a, int b) Computes the remainder of the division of a by b.
static int	nextPowerOfTwo(int value) Fast method of finding the next power of 2 greater than or equal to the supplied value.
static long	nextPowerOfTwo(long value) Fast method of finding the next power of 2 greater than or equal to the supplied value.
static int	normalize(int value, int factor) Divide value by factor, take the smallest integer greater than or equal to the result, multiply that integer by factor, and return it.
static long	normalize(long value, int factor) Divide value by factor, take the smallest integer greater than or equal to the result, multiply that integer by factor, and return it.

Methods inherited from class java.lang.Object

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

Method Detail

isPowerOfTwo

public static boolean isPowerOfTwo(long x)

Return true if input argument is power of two. Input has to be a a positive integer.

Result is undefined for zero or negative integers.

Parameters:

x - test x to see if it is a power of two

Returns:

true if x is power of two

modPowerOfTwo

public static int modPowerOfTwo(int a,
                                int b)

Computes the remainder of the division of a by b. a has to be a non-negative integer and b has to be a power of two, otherwise the result is undefined.

Parameters:

a - divide a by b. a must be a non-negative integer

b - divide a by b. b must be a power of two

Returns:

remainder of the division of a by b.

modPowerOfTwo

public static long modPowerOfTwo(long a,
                                 int b)

Computes the remainder of the division of a by b. a has to be a non-negative integer and b has to be a power of two, otherwise the result is undefined.

Parameters:

a - divide a by b. a must be a non-negative integer

b - divide a by b. b must be a power of two

Returns:

remainder of the division of a by b.

nextPowerOfTwo

public static int nextPowerOfTwo(int value)

Fast method of finding the next power of 2 greater than or equal to the supplied value.

If the value is <= 0 then 1 will be returned.

This method is not suitable for Integer.MIN_VALUE or numbers greater than 2^30.

Parameters:

value - from which to search for next power of 2

Returns:

The next power of 2 or the value itself if it is a power of 2

nextPowerOfTwo

public static long nextPowerOfTwo(long value)

Fast method of finding the next power of 2 greater than or equal to the supplied value.

If the value is <= 0 then 1 will be returned.

This method is not suitable for Long.MIN_VALUE or numbers greater than 2^62.

Parameters:

value - from which to search for next power of 2

Returns:

The next power of 2 or the value itself if it is a power of 2

log2

public static int log2(int value)

Return the log 2 result for this int.

Parameters:

value - the int value

Returns:

the log 2 result for value

log2

public static int log2(long value)

Return the log 2 result for this long.

Parameters:

value - the long value

Returns:

the log 2 result for value

divideByAndCeilToInt

public static int divideByAndCeilToInt(double d,
                                       int k)

Divide d by k and return the smallest integer greater than or equal to the result.

Parameters:

d - divide d by k

k - divide d by k

Returns:

the smallest integer greater than or equal to the result

divideByAndCeilToLong

public static long divideByAndCeilToLong(double d,
                                         int k)

Divide d by k and return the smallest integer greater than or equal to the result.

Parameters:

d - divide d by k

k - divide d by k

Returns:

the smallest integer greater than or equal to the result

divideByAndRoundToInt

public static int divideByAndRoundToInt(double d,
                                        int k)

Divide d by k and return the int value closest to the result.

Parameters:

d - divide d by k

k - divide d by k

Returns:

the int value closest to the result

divideByAndRoundToLong

public static long divideByAndRoundToLong(double d,
                                          int k)

Divide d by k and return the long value closest to the result.

Parameters:

d - divide d by k

k - divide d by k

Returns:

the long value closest to the result

normalize

public static int normalize(int value,
                            int factor)

Divide value by factor, take the smallest integer greater than or equal to the result, multiply that integer by factor, and return it.

Parameters:

value - normalize this value by factor

factor - normalize this value by factor

Returns:

the result of value being normalized by factor

normalize

public static long normalize(long value,
                             int factor)

Divide value by factor, take the smallest integer greater than or equal to the result, multiply that integer by factor, and return it.

Parameters:

value - normalize this value by factor

factor - normalize this value by factor

Returns:

the result of value being normalized by factor

bytesToHex

public static String bytesToHex(byte[] in)

compareIntegers

public static int compareIntegers(int i1,
                                  int i2)

Compares two integers

Parameters:

i1 - First number to compare with second one

i2 - Second number to compare with first one

Returns:

+1 if i1 > i2, -1 if i2 > i1, 0 if i1 and i2 are equals

compareLongs

public static int compareLongs(long l1,
                               long l2)

Compares two longs

Parameters:

l1 - First number to compare with second one

l2 - Second number to compare with first one

Returns:

+1 if l1 > l2, -1 if l2 > l1, 0 if l1 and l2 are equals