std/random

Pseudo-random number generator (PRNG).

#include "std/random"

Xorshift

The PRNG uses the Xorshift algorithm. It is not cryptographically secure.

State

The PRNG has a single global state:

var std_prng_random_state int

Global variables are zero-initialized. To get non-deterministic output, seed the state explicitly.

Seeding

set_random_seed

pub func void set_random_seed[int seed]

Sets the PRNG state to seed.

12345 call set_random_seed

Generating

random

pub func int random[]

Advances the PRNG state and returns the next value.

call random    // some int

random_range

pub func int random_range[int to]

Returns a value in 0..to-1.

10 random_range    // 0..9

/// warning "Not modulo-bias-free" random_range uses modulo, which introduces a slight bias when to is not a power of two. For most uses this is acceptable.

Internals

prng_randomize_state_xorshift

pub func void prng_randomize_state_xorshift[]

Advances the PRNG state with the Xorshift step. Called by random.

call prng_randomize_state_xorshift