janet-pcg-random

Janet bindings for the PCG Random pseudo random number generator.

Status

Early stage, expect changes :)

Installation

jpm install https://github.com/sogaiu/janet-pcg-random

Usage

Make module available:

(import pcgrand)

pcgrand/make creates a seeded generator instance:

(pcgrand/make (int/u64 "1") (int/u64 "1"))
# =>
<pcgrand/rng 0x5570B7F0EF80>

Use two int/64 values to seed: the state initializer and sequence selection constant (stream id).

pcgrand/random returns a uniformly distributed 32-bit integer:

(def rng
  (pcgrand/make (int/u64 "1") (int/u64 "1")))
# =>
<pcgrand/rng 0x55E021F18930>

(pcgrand/random rng)
# =>
-914190447

(:random rng)
# =>
361947764

pcgrand/boundedrand returns a uniformly distributed integer, i, where 0 <= i < bound:

(def rng
  (pcgrand/make (int/u64 "1") (int/u64 "1")))
# =>
<pcgrand/rng 0x55E021F1A3C0>

(pcgrand/boundedrand rng 28)
# =>
9

(:boundedrand rng 9)
# =>
2

pcgrand/srandom seeds a generator using two int/u64 values in a manner similar to pcgrand/make:

(def rng
  (pcgrand/make (int/u64 "1") (int/u64 "1")))
# =>
<pcgrand/rng 0x55E021F1AFB0>

(pcgrand/random rng)
# =>
-914190447

(:random rng)
# =>
361947764

(pcgrand/srandom rng (int/u64 "1") (int/u64 "1"))
# =>
nil

(:random rng)
# =>
-914190447

Acknowledgments

• andrewchambers - discussion, sample code
• bakpakin - janet, sample code
• cellularmitosis - documented sample code
• imneme - pcg-random
• pyrmont - documented sample code