pcg.nim

#[  Written by Tommy Ettinger in 2017, based on work by Melissa O'Neill in 2015:
PCG-Random, http://www.pcg-random.org/

To the extent possible under law, the author has dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.

See <http://creativecommons.org/publicdomain/zero/1.0/>. ]#

var x*: uint64 # The state can be seeded with any value.

proc next*(): uint64 =
  x += 0x9E3779B97F4A7C15u64
  var z = (x xor (x shr (5u64 + (x shr 59)))) * 0xAEF17502108EF2D9u64;
  z xor (z shr 43)

rng.nim

#[  Written in 2015 by Sebastiano Vigna (vigna@acm.org)

To the extent possible under law, the author has dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.

See <http://creativecommons.org/publicdomain/zero/1.0/>. ]#

#[ This is a fixed-increment version of Java 8's SplittableRandom generator
   See http://dx.doi.org/10.1145/2714064.2660195 and 
   http://docs.oracle.com/javase/8/docs/api/java/util/SplittableRandom.html

   It is a very fast generator passing BigCrush, and it can be useful if
   for some reason you absolutely want 64 bits of state; otherwise, we
   rather suggest to use a xoroshiro128+ (for moderately parallel
   computations) or xorshift1024* (for massively parallel computations)
   generator. ]#

var x*: uint64 # The state can be seeded with any value.

proc next*(): uint64 =
  x += 0x9E3779B97F4A7C15u64
  var z = x
  z = (z xor `shr`(z, 30)) * 0xBF58476D1CE4E5B9u64
  z = (z xor `shr`(z, 27)) * 0x94D049BB133111EBu64
  z xor `shr`(z, 31)

when isMainModule:
  x = 0
  assert next() == 16294208416658607535u64

  x = 100
  assert next() == 2532601429470541124u64

thrust.nim

#[ Written by Tommy Ettinger in 2017

To the extent possible under law, the author has dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.

See <http://creativecommons.org/publicdomain/zero/1.0/>. ]#

#[ This is ThrustRNG, a deceptively-small pseudo-random number generator
   that passes difficult quality tests and is faster than PCG-Random
   and SplitMix64 in most cases, while maintaining a period of 2 to the
   64 and using the same general cipher-like structure as those two. ]#

var x*: uint64 # The state x can be seeded with any value.

proc next*(): uint64 =
  x += 0x9E3779B97F4A7C15u64
  var z = (x xor (x shr 30)) * 0x5851F42D4C957F2Du64
  z xor (z shr 28)