java.lang.Object
- org.apache.commons.rng.core.BaseProvider

All Implemented Interfaces:

RestorableUniformRandomProvider, UniformRandomProvider

Direct Known Subclasses:

IntProvider, LongProvider
```
public abstract class BaseProvider
extends java.lang.Object
implements RestorableUniformRandomProvider
```
Base class with default implementation for common methods.

Field Summary

Fields
Modifier and Type	Field	Description
`private static int`	`GOLDEN_RATIO_32`	The fractional part of the golden ratio, phi, scaled to 32-bits and rounded to odd.
`private static long`	`GOLDEN_RATIO_64`	The fractional part of the golden ratio, phi, scaled to 64-bits and rounded to odd.

Constructor Summary

Constructors
Constructor Description

BaseProvider()
Create an instance.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`protected void`	`checkIndex(int min, int max, int index)`	Checks whether `index` is in the range `[min, max]`.
`protected void`	`checkStateSize(byte[] state, int expected)`	Deprecated. Method is used internally and should be made private in some future release.
`protected byte[]`	`composeStateInternal(byte[] state, byte[] parentState)`	Combine parent and subclass states.
`protected static int[]`	`extendSeed(int[] seed, int length)`	Extend the seed to the specified minimum length.
`protected static long[]`	`extendSeed(long[] seed, int length)`	Extend the seed to the specified minimum length.
`protected void`	`fillState(int[] state, int[] seed)`	Simple filling procedure.
`protected void`	`fillState(long[] state, long[] seed)`	Simple filling procedure.
`protected byte[]`	`getStateInternal()`	Creates a snapshot of the RNG state.
`private static int`	`murmur3(int x)`	Perform the finalising 32-bit mix function of Austin Appleby's MurmurHash3.
`void`	`restoreState(RandomProviderState state)`	Restores the state of a generator.
`RandomProviderState`	`saveState()`	Saves the state of a generator.
`private static long`	`scramble(long n, long mult, int shift, int add)`	Transformation used to scramble the initial state of a generator.
`private static long`	`scrambleWell(long n, int add)`	Transformation used to scramble the initial state of a generator.
`protected void`	`setStateInternal(byte[] state)`	Resets the RNG to the given `state`.
`protected byte[][]`	`splitStateInternal(byte[] state, int localStateLength)`	Splits the given `state` into a part to be consumed by the caller in order to restore its local state, while the reminder is passed to the parent class.
`private static long`	`stafford13(long x)`	Perform variant 13 of David Stafford's 64-bit mix function.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.commons.rng.UniformRandomProvider
doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextBytes, nextBytes, nextDouble, nextDouble, nextDouble, nextFloat, nextFloat, nextFloat, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong

- Field Detail
  - GOLDEN_RATIO_64
```
private static final long GOLDEN_RATIO_64
```
    The fractional part of the golden ratio, phi, scaled to 64-bits and rounded to odd.
    phi = (sqrt(5) - 1) / 2) * 2^64
    See Also:
    
    Golden ratio, Constant Field Values
  - GOLDEN_RATIO_32
```
private static final int GOLDEN_RATIO_32
```
    The fractional part of the golden ratio, phi, scaled to 32-bits and rounded to odd.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - BaseProvider
```
public BaseProvider()
```
    Create an instance.
- Method Detail
  - saveState
```
public RandomProviderState saveState()
```
    Saves the state of a generator.
    
    Specified by:
    
    saveState in interface RestorableUniformRandomProvider
    
    Returns:
    
    the current state of this instance. It is a value that can subsequently be passed to the restore method.
  - restoreState
```
public void restoreState(RandomProviderState state)
```
    Restores the state of a generator.
    
    Specified by:
    
    restoreState in interface RestorableUniformRandomProvider
    
    Parameters:
    
    state - State which this instance will be set to. This parameter would usually have been obtained by a call to saveState performed either on the same object as this one, or an object of the exact same class.
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - composeStateInternal
```
protected byte[] composeStateInternal(byte[] state,
                                      byte[] parentState)
```
    Combine parent and subclass states. This method must be called by all subclasses in order to ensure that state can be restored in case some of it is stored higher up in the class hierarchy. I.e. the body of the overridden getStateInternal(), will end with a statement like the following:
    return composeStateInternal(state, super.getStateInternal());
    where state is the state needed and defined by the class where the method is overridden.
    Parameters:
    
    state - State of the calling class.
    
    parentState - State of the calling class' parent.
    
    Returns:
    
    the combined state. Bytes that belong to the local state will be stored at the beginning of the resulting array.
  - splitStateInternal
```
protected byte[][] splitStateInternal(byte[] state,
                                      int localStateLength)
```
    Splits the given state into a part to be consumed by the caller in order to restore its local state, while the reminder is passed to the parent class. I.e. the body of the overridden setStateInternal(byte[]), will contain statements like the following:
    final byte[][] s = splitState(state, localStateLength); // Use "s[0]" to recover the local state. super.setStateInternal(s[1]);
    where state is the combined state of the calling class and of all its parents.
    Parameters:
    
    state - State. The local state must be stored at the beginning of the array.
    
    localStateLength - Number of elements that will be consumed by the locally defined state.
    
    Returns:
    
    the local state (in slot 0) and the parent state (in slot 1).
    
    Throws:
    
    java.lang.IllegalStateException - if state.length < localStateLength.
  - getStateInternal
```
protected byte[] getStateInternal()
```
    Creates a snapshot of the RNG state.
    
    Returns:
    
    the internal state.
  - setStateInternal
```
protected void setStateInternal(byte[] state)
```
    Resets the RNG to the given state.
    
    Parameters:
    
    state - State (previously obtained by a call to getStateInternal()).
    
    Throws:
    
    java.lang.IllegalStateException - if the size of the given array is not consistent with the state defined by this class.
    
    See Also:
    
    checkStateSize(byte[],int)
  - fillState
```
protected void fillState(int[] state,
                         int[] seed)
```
    Simple filling procedure. It will
    
    fill the beginning of state by copying min(seed.length, state.length) elements from seed,
    
    set all remaining elements of state with non-zero values (even if seed.length < state.length).
    Parameters:
    
    state - State. Must be allocated.
    
    seed - Seed. Cannot be null.
  - fillState
```
protected void fillState(long[] state,
                         long[] seed)
```
    Simple filling procedure. It will
    
    fill the beginning of state by copying min(seed.length, state.length) elements from seed,
    
    set all remaining elements of state with non-zero values (even if seed.length < state.length).
    Parameters:
    
    state - State. Must be allocated.
    
    seed - Seed. Cannot be null.
  - checkStateSize
```
@Deprecated
protected void checkStateSize(byte[] state,
                              int expected)
```
    Deprecated.
    Method is used internally and should be made private in some future release.
    
    Checks that the state has the expected size.
    
    Parameters:
    
    state - State.
    
    expected - Expected length of state array.
    
    Throws:
    
    java.lang.IllegalStateException - if state.length < expected.
  - checkIndex
```
protected void checkIndex(int min,
                          int max,
                          int index)
```
    Checks whether index is in the range [min, max].
    
    Parameters:
    
    min - Lower bound.
    
    max - Upper bound.
    
    index - Value that must lie within the [min, max] interval.
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if index is not within the [min, max] interval.
  - scramble
```
private static long scramble(long n,
                             long mult,
                             int shift,
                             int add)
```
    Transformation used to scramble the initial state of a generator.
    
    Parameters:
    
    n - Seed element.
    
    mult - Multiplier.
    
    shift - Shift.
    
    add - Offset.
    
    Returns:
    
    the transformed seed element.
  - scrambleWell
```
private static long scrambleWell(long n,
                                 int add)
```
    Transformation used to scramble the initial state of a generator.
    
    Parameters:
    
    n - Seed element.
    
    add - Offset.
    
    Returns:
    
    the transformed seed element.
    
    See Also:
    
    scramble(long,long,int,int)
  - extendSeed
```
protected static long[] extendSeed(long[] seed,
                                   int length)
```
    Extend the seed to the specified minimum length. If the seed is equal or greater than the minimum length, return the same seed unchanged. Otherwise:
    
    Create a new array of the specified length
    Copy all elements of the seed into the array
    Fill the remaining values. The additional values will have at most one occurrence of zero. If the original seed is all zero, the first extended value will be non-zero.
    
    This method can be used in constructors that must pass their seed to the super class to avoid a duplication of seed expansion to the minimum length required by the super class and the class:
    public RNG extends AnotherRNG { public RNG(long[] seed) { super(seed = extendSeed(seed, SEED_SIZE)); // Use seed for additional state ... } }
    
    Note using the state filling procedure provided in fillState(long[], long[]) is not possible as it is an instance method. Calling a seed extension routine must use a static method.
    This method functions as if the seed has been extended using a SplitMix64 generator seeded with seed[0], or zero if the input seed length is zero.
    if (seed.length < length) { final long[] s = Arrays.copyOf(seed, length); final SplitMix64 rng = new SplitMix64(s[0]); for (int i = seed.length; i < length; i++) { s[i] = rng.nextLong(); } return s; }
    Parameters:
    
    seed - Input seed
    
    length - The minimum length
    
    Returns:
    
    the seed
    
    Since:
    
    1.5
  - extendSeed
```
protected static int[] extendSeed(int[] seed,
                                  int length)
```
    Extend the seed to the specified minimum length. If the seed is equal or greater than the minimum length, return the same seed unchanged. Otherwise:
    
    Create a new array of the specified length
    Copy all elements of the seed into the array
    Fill the remaining values. The additional values will have at most one occurrence of zero. If the original seed is all zero, the first extended value will be non-zero.
    
    This method can be used in constructors that must pass their seed to the super class to avoid a duplication of seed expansion to the minimum length required by the super class and the class:
    public RNG extends AnotherRNG { public RNG(int[] seed) { super(seed = extendSeed(seed, SEED_SIZE)); // Use seed for additional state ... } }
    
    Note using the state filling procedure provided in fillState(int[], int[]) is not possible as it is an instance method. Calling a seed extension routine must use a static method.
    This method functions as if the seed has been extended using a SplitMix64-style 32-bit generator seeded with seed[0], or zero if the input seed length is zero. The generator uses the 32-bit mixing function from MurmurHash3.
    Parameters:
    
    seed - Input seed
    
    length - The minimum length
    
    Returns:
    
    the seed
    
    Since:
    
    1.5
  - stafford13
```
private static long stafford13(long x)
```
    Perform variant 13 of David Stafford's 64-bit mix function. This is the mix function used in the SplitMix64 RNG.
    This is ranked first of the top 14 Stafford mixers.
    This function can be used to mix the bits of a long value to obtain a better distribution and avoid collisions between similar values.
    
    Parameters:
    
    x - the input value
    
    Returns:
    
    the output value
    
    See Also:
    
    Better Bit Mixing - Improving on MurmurHash3's 64-bit Finalizer.
  - murmur3
```
private static int murmur3(int x)
```
    Perform the finalising 32-bit mix function of Austin Appleby's MurmurHash3.
    This function can be used to mix the bits of a int value to obtain a better distribution and avoid collisions between similar values.
    
    Parameters:
    
    x - the input value
    
    Returns:
    
    the output value
    
    See Also:
    
    SMHasher

Class BaseProvider

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.commons.rng.UniformRandomProvider

Field Detail

GOLDEN_RATIO_64

GOLDEN_RATIO_32

Constructor Detail

BaseProvider

Method Detail

saveState

restoreState

toString

composeStateInternal

splitStateInternal

getStateInternal

setStateInternal

fillState

fillState

checkStateSize

checkIndex

scramble

scrambleWell

extendSeed

extendSeed

stafford13

murmur3