tf::Xorshift< T > Class Template Reference

class to create a fast xorshift-based pseudo-random number generator More...

#include <taskflow/utility/math.hpp>

Public Member Functions
	Xorshift ()=default
	constructs an uninitialized xor-shift generator
	Xorshift (T value)
	constructs a xor-shift generator with the given seed
void	seed (T value)
	seeds the generator with a new value
T	operator() ()
	generates the next pseudo-random value

Detailed Description

template<typename T>
class tf::Xorshift< T >

class to create a fast xorshift-based pseudo-random number generator

Template Parameters

T	unsigned integral type used as the internal state (supported uint32_t and uint64_t)

This class implements a lightweight xorshift pseudo-random number generator suitable for performance-critical paths such as schedulers, work-stealing victim selection, and randomized backoff. The implementation is branchless on the hot path and has a very small state footprint (one machine word). All operations are integer-only.

Attention

The internal state must be seeded with a non-zero value. This class is not thread-safe. Each thread should maintain its own instance.

Constructor & Destructor Documentation

Xorshift() [1/2]

template<typename T >

tf::Xorshift< T >::Xorshift ( )

default

constructs an uninitialized xor-shift generator

The internal state is not initialized. The user must call seed() with a non-zero value before generating numbers.

Xorshift() [2/2]

template<typename T >

tf::Xorshift< T >::Xorshift ( T value )

inline

constructs a xor-shift generator with the given seed

Parameters

value

the new seed value to use

The seed value must be non-zero.

Member Function Documentation

operator()()

template<typename T >

T tf::Xorshift< T >::operator() ( )

inline

generates the next pseudo-random value

Returns

a pseudo-random value of type T

For 32-bit state, this function implements the Xorshift32 algorithm. For 64-bit state, this function implements the Xorshift64 algorithm with a multiplicative output transformation to improve distribution.

Warning

Calling this function before seeding the generator with a non-zero value results in undefined behavior.

seed()

template<typename T >

void tf::Xorshift< T >::seed ( T value )

inline

seeds the generator with a new value

Parameters

value

the new seed value

The seed value must be non-zero. A zero seed results in a degenerated generator that always returns zero.

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The documentation for this class was generated from the following file:

• taskflow/utility/math.hpp