org.h2.util
Class MathUtils

java.lang.Object
  org.h2.util.MathUtils

public class MathUtils
extends java.lang.Object

This is a utility class with mathematical helper functions.

Method Summary

static void	checkPowerOf2(int len) Check if a value is a power of two.
static int	compare(int a, int b) Compare two values.
static int	compare(long a, long b) Compare two values.
static int	convertLongToInt(long l) Convert a long value to an int value.
static byte	decodeByte(java.lang.String s) Parse a string to a byte.
static int	decodeInt(java.lang.String s) Parse a string to an int.
static long	decodeLong(java.lang.String s) Parse a string to a long.
static short	decodeShort(java.lang.String s) Parse a string to a short.
static int	nextPowerOf2(int x) Get the value that is equal or higher than this value, and that is a power of two.
static int	reverse(int x) Reverse the bits in a 32 bit integer.
static long	reverse(long x) Reverse the bits in a 64 bit long.
static int	roundUp(int x, int blockSizePowerOf2) Round the value up to the next block size.
static long	roundUpLong(long x, long blockSizePowerOf2) Round the value up to the next block size.
static long	scaleUp50Percent(long start, long min, long blockSize, long maxIncrease) Increase the value by about 50%.
static java.math.BigDecimal	setScale(java.math.BigDecimal bd, int scale) Set the scale of a BigDecimal value.

Methods inherited from class java.lang.Object

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

Method Detail

roundUp

public static int roundUp(int x,
                          int blockSizePowerOf2)

Round the value up to the next block size. The block size must be a power of two. As an example, using the block size of 8, the following rounding operations are done: 0 stays 0; values 1..8 results in 8, 9..16 results in 16, and so on.

Parameters:

x - the value to be rounded

blockSizePowerOf2 - the block size

Returns:

the rounded value

roundUpLong

public static long roundUpLong(long x,
                               long blockSizePowerOf2)

Round the value up to the next block size. The block size must be a power of two. As an example, using the block size of 8, the following rounding operations are done: 0 stays 0; values 1..8 results in 8, 9..16 results in 16, and so on.

Parameters:

x - the value to be rounded

blockSizePowerOf2 - the block size

Returns:

the rounded value

checkPowerOf2

public static void checkPowerOf2(int len)

Check if a value is a power of two.

Parameters:

len - the value to check

Throws:

java.lang.RuntimeException - if it is not a power of two

nextPowerOf2

public static int nextPowerOf2(int x)

Get the value that is equal or higher than this value, and that is a power of two.

Parameters:

x - the original value

Returns:

the next power of two value

scaleUp50Percent

public static long scaleUp50Percent(long start,
                                    long min,
                                    long blockSize,
                                    long maxIncrease)

Increase the value by about 50%. The method is used to increase the file size in larger steps.

Parameters:

start - the smallest possible returned value

min - the current value

blockSize - the block size

maxIncrease - the maximum increment

Returns:

the new value

setScale

public static java.math.BigDecimal setScale(java.math.BigDecimal bd,
                                            int scale)
                                     throws java.sql.SQLException

Set the scale of a BigDecimal value.

Parameters:

bd - the BigDecimal value

scale - the new scale

Returns:

the scaled value

Throws:

java.sql.SQLException

decodeByte

public static byte decodeByte(java.lang.String s)

Parse a string to a byte. This method uses the decode method to support decimal, hexadecimal and octal values.

Parameters:

s - the string to parse

Returns:

the value

decodeShort

public static short decodeShort(java.lang.String s)

Parse a string to a short. This method uses the decode method to support decimal, hexadecimal and octal values.

Parameters:

s - the string to parse

Returns:

the value

decodeInt

public static int decodeInt(java.lang.String s)

Parse a string to an int. This method uses the decode method to support decimal, hexadecimal and octal values.

Parameters:

s - the string to parse

Returns:

the value

decodeLong

public static long decodeLong(java.lang.String s)

Parse a string to a long. This method uses the decode method to support decimal, hexadecimal and octal values.

Parameters:

s - the string to parse

Returns:

the value

convertLongToInt

public static int convertLongToInt(long l)

Convert a long value to an int value. Values larger than the biggest int value is converted to the biggest int value, and values smaller than the smallest int value are converted to the smallest int value.

Parameters:

l - the value to convert

Returns:

the converted int value

reverse

public static int reverse(int x)

Reverse the bits in a 32 bit integer. This code is also available in Java 5 using Integer.reverse, however not available yet in Retrotranslator. The code was taken from http://www.hackersdelight.org - reverse.c

Parameters:

x - the original value

Returns:

the value with reversed bits

reverse

public static long reverse(long x)

Reverse the bits in a 64 bit long. This code is also available in Java 5 using Long.reverse, however not available yet in Retrotranslator.

Parameters:

x - the original value

Returns:

the value with reversed bits

compare

public static int compare(int a,
                          int b)

Compare two values. Returns -1 if the first value is smaller, 1 if bigger, and 0 if equal.

Parameters:

a - the first value

b - the second value

Returns:

the result

compare

public static int compare(long a,
                          long b)

Compare two values. Returns -1 if the first value is smaller, 1 if bigger, and 0 if equal.

Parameters:

a - the first value

b - the second value

Returns:

the result