PHP Manual: Constructs a new PCG Oneseq 128 XSL RR 64 engine

Description

public Random\Engine\PcgOneseq128XslRr64::__construct(stringintnull $seed = null)

Parameters

seed

How the internal 128 bit (16 byte) state consisting of one unsigned 128 bit integer is seeded depends on the type used as the seed.

Type	Description
null	Fills the state with 16 random bytes generated using the CSPRNG.
int	Fills the state by setting the state to `0`, advancing the engine one step, adding the value of `seed` interpreted as an unsigned 64 bit integer, and advancing the engine another step.
string	Fills the state by interpreting a 16 byte string as a little-endian unsigned 128 bit integer.

Errors/Exceptions

If the length of a string seed is not 16 bytes, a ValueError will be thrown.

Examples

Example #1 Random\Engine\PcgOneseq128XslRr64::__construct example

<?php
// Uses a random 128 Bit seed.
$e = new \Random\Engine\PcgOneseq128XslRr64();

$r = new \Random\Randomizer($e);
?>

Example #2 Deriving a seed from a string

<?php
$string = "My string seed";

// Hash the string with truncated SHA-256 using binary output
// to turn the $string into a 128 Bit seed. Using the same
// string will result in the same sequence of randomness.
$e = new \Random\Engine\PcgOneseq128XslRr64(
    substr(hash('sha256', $string, binary: true), 0, 16)
);

echo bin2hex($e->generate()), "\n";
?>

The above example will output:

8333ef59315b16d8