com.google.uzaygezen.core

Class MathUtils

java.lang.Object

com.google.uzaygezen.core.MathUtils

public class MathUtils
extends Object

Math utilities.

Author:

Daniel Aioanei

Method Summary

Methods

Modifier and Type	Method and Description
static int	bitCountToByteCount(int bitCount) Computes the minimum number of bytes needed to cover bitCount bits.
static double	bytesToDouble(byte[] bytes) Inverse of doubleToBytes(double).
static byte[]	doubleToBytes(double value) Computes the big-endian byte array representation of the IEEE-754 8 byte encoding of value.
static int	gcd(int a, int b) Computes the greatest common divisor of two integers.
static byte[]	nonNegativeLongToBigEndianBytes(int byteCount, long value) Produces the big-endian byte array representation of value.
static int	numberOfLeadingZeros(byte b) Unfortunately there is no Byte.numberOfLeadingZeros method.
static long	unsignedBigEndianBytesToNonNegativeLong(byte[] bytes)

Methods inherited from class java.lang.Object

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

Method Detail

gcd

public static int gcd(int a,
      int b)

Computes the greatest common divisor of two integers. Semantically equivalent to BigInteger.valueOf(a).gcd(BigInteger.valueOf(b)) .intValue(), but normally faster.

nonNegativeLongToBigEndianBytes

public static byte[] nonNegativeLongToBigEndianBytes(int byteCount,
                                     long value)

Produces the big-endian byte array representation of value. The number must be non-negative and less than 1 << 8 * byteCount). In other words, the big endian representation, without the bit sign, must fit into byteCount bytes.

Parameters:

byteCount - the fixed size wanted for the result

value - the number

Returns:

the fixed size big-endian byte array representation of value. The original number can be recovered via unsignedBigEndianBytesToNonNegativeLong(1, result).

unsignedBigEndianBytesToNonNegativeLong

public static long unsignedBigEndianBytesToNonNegativeLong(byte[] bytes)

bitCountToByteCount

public static int bitCountToByteCount(int bitCount)

Computes the minimum number of bytes needed to cover bitCount bits.

doubleToBytes

public static byte[] doubleToBytes(double value)

Computes the big-endian byte array representation of the IEEE-754 8 byte encoding of value.

bytesToDouble

public static double bytesToDouble(byte[] bytes)

Inverse of doubleToBytes(double).

numberOfLeadingZeros

public static int numberOfLeadingZeros(byte b)

Unfortunately there is no Byte.numberOfLeadingZeros method.

Returns:

Number of leading zeroes (up to 8) of a byte.