tvm::support::LinearCongruentialEngine Class Reference

This linear congruential engine is a drop-in replacement for std::minstd_rand. It strictly corresponds to std::minstd_rand and is designed to be platform-independent. More...

#include <random_engine.h>

Collaboration diagram for tvm::support::LinearCongruentialEngine:

Public Types
using	TRandState = int64_t
using	result_type = uint64_t
	The result type. More...

Public Member Functions
result_type	operator() ()
	Operator to move the random state to the next and return the new random state. According to definition of linear congruential engine, the new random state value is computed as new_random_state = (current_random_state * multiplier + increment) % modulus. More...
void	Seed (TRandState rand_state)
	Change the start random state of RNG with the seed of a new random state value. More...
TRandState	ForkSeed ()
	Fork a new seed for another RNG from current random state. More...
	LinearCongruentialEngine (TRandState *rand_state_ptr)
	Construct a random number generator with a random state pointer. More...

Static Public Member Functions
static constexpr result_type	min ()
	The minimum possible value of random state here. More...
static constexpr result_type	max ()
	The maximum possible value of random state here. More...
static TRandState	DeviceRandom ()
	Get a device random state. More...
static TRandState	NormalizeSeed (TRandState rand_state)
	Normalize the random seed to the range of [1, modulus - 1]. More...

Static Public Attributes
static constexpr TRandState	multiplier = 48271
	The multiplier. More...
static constexpr TRandState	increment = 0
	The increment. More...
static constexpr TRandState	modulus = 2147483647
	The modulus. More...

Detailed Description

This linear congruential engine is a drop-in replacement for std::minstd_rand. It strictly corresponds to std::minstd_rand and is designed to be platform-independent.

Note

Our linear congruential engine is a complete implementation of std::uniform_random_bit_generator so it can be used as generator for any STL random number distribution. However, parts of std::linear_congruential_engine's member functions are not included for simplification. For full member functions of std::minstd_rand, please check out the following link: https://en.cppreference.com/w/cpp/numeric/random/linear_congruential_engine

Member Typedef Documentation

result_type

using tvm::support::LinearCongruentialEngine::result_type = uint64_t

The result type.

TRandState

using tvm::support::LinearCongruentialEngine::TRandState = int64_t

Constructor & Destructor Documentation

LinearCongruentialEngine()

tvm::support::LinearCongruentialEngine::LinearCongruentialEngine ( TRandState *  rand_state_ptr )

inlineexplicit

Construct a random number generator with a random state pointer.

Parameters

rand_state_ptr

The random state pointer given in result_type*.

Note

The random state is not checked for whether it's nullptr and whether it's in the range of [0, modulus-1]. We assume the given random state is valid or the Seed function would be called right after the constructor before any usage.

Member Function Documentation

DeviceRandom()

static TRandState tvm::support::LinearCongruentialEngine::DeviceRandom ( )

inlinestatic

Get a device random state.

Returns

The random state

ForkSeed()

TRandState tvm::support::LinearCongruentialEngine::ForkSeed ( )

inline

Fork a new seed for another RNG from current random state.

Returns

The forked seed.

max()

static constexpr result_type tvm::support::LinearCongruentialEngine::max ( )

inlinestaticconstexpr

The maximum possible value of random state here.

min()

static constexpr result_type tvm::support::LinearCongruentialEngine::min ( )

inlinestaticconstexpr

The minimum possible value of random state here.

NormalizeSeed()

static TRandState tvm::support::LinearCongruentialEngine::NormalizeSeed ( TRandState  rand_state )

inlinestatic

Normalize the random seed to the range of [1, modulus - 1].

Parameters

rand_state

The random seed.

Returns

The normalized random seed.

operator()()

result_type tvm::support::LinearCongruentialEngine::operator() ( )

inline

Operator to move the random state to the next and return the new random state. According to definition of linear congruential engine, the new random state value is computed as new_random_state = (current_random_state * multiplier + increment) % modulus.

Returns

The next current random state value in the type of result_type.

Note

In order for better efficiency, the implementation here has a few assumptions:

1. The multiplication and addition won't overflow.
2. The given random state pointer rand_state_ptr is not nullptr.
3. The given random state *(rand_state_ptr) is in the range of [0, modulus - 1].

Seed()

void tvm::support::LinearCongruentialEngine::Seed ( TRandState  rand_state )

inline

Change the start random state of RNG with the seed of a new random state value.

Parameters

rand_state

The random state given in result_type.

Member Data Documentation

increment

constexpr TRandState tvm::support::LinearCongruentialEngine::increment = 0

staticconstexpr

The increment.

modulus

constexpr TRandState tvm::support::LinearCongruentialEngine::modulus = 2147483647

staticconstexpr

The modulus.

multiplier

constexpr TRandState tvm::support::LinearCongruentialEngine::multiplier = 48271

staticconstexpr

The multiplier.

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

• include/tvm/support/random_engine.h