Mersenne Twister

English | 日本語

JavaScript implementation of Mersenne Twister for Pokémon RNG Manipulation.

Note

Note This library is designed and implemented for Pokémon RNG Manipulation, not for general use. For simulation and other applications, please use another library.

Features

From the original Mersenne Twister, we have devised a way to reduce the amount of table calculations for instance creation and internal state updates.

Installation

Add the following line to the .npmrc file

@ngen-rng:registry="https://npm.pkg.github.com"

npm

npm install @ngen-rng/mersenne-twister

yarn

yarn add @ngen-rng/mersenne-twister

Usage

import { MersenneTwister } from '@ngen-rng/mersenne-twister';

// The amount of table calculations during MT initialization is 624 times.
const mt1 = new MersenneTwister(0xadfa2178);

// Get a random number value with the 'getRandom' function.
mt1.getRandom(); // 4204083817

// Get the current random number table reference index.
mt1.getIndex(); // 2

// Get an array of random values with the 'slice' function.
// The 'slice' function specifies the start and end.
// Also, the 'slice' function does not update the state.
const slice1 = mt1.slice(2, 3)[0]; // 2076987897
mt1.getRandom(); // 2076987897

// The amount of calculations for table updates is also 624 times.
mt1.tableUpdate();

// Reduce the amount of table calculations during MT initialization to 402 times.
const mt2 = new MersenneTwister(0xadfa2178, 402);

// Get a random number value. (same value as mt1)
mt2.getRandom(); // 4204083817

// The amount of calculations for table updates is also 402 times.
mt2.tableUpdate();

// If the table calculation is reduced to 402/624, the range to obtain the same value is 0 to 5.
mt1.slice(0, 6).map((p) => p >>> 27); // [31, 31, 31, 31, 31, 31]
mt2.slice(0, 6).map((p) => p >>> 27); // [31, 31, 31, 31, 31, 31]

// Discards a specified number of random values.
mt1.discard(6);
mt2.discard(6);

// Because of the different table computations, the values of mt1 and mt2 will not necessarily be the same.
mt1.getRandom() >>> 27; // 29
mt2.getRandom() >>> 27; // 15

Author

• Author: ngen-rng
• E-mail: [email protected]

License

• @ngen-rng/mersenne-twister: MIT LICENSE
• The original Mersenne Twister: MIT LICENSE
  • Reference: The original Mersenne Twister algorithm