Pseudo-random numbers/Xorshift star: Difference between revisions

=={{header|Nim}}==

<lang Nim>import algorithm, sequtils, strutils, tables

const C = 0x2545F4914F6CDD1Du64

type XorShift = object

state: uint64

func seed(gen: var XorShift; num: uint64) =

gen.state = num

func nextInt(gen: var XorShift): uint32 =

var x = gen.state

x = x xor x shr 12

x = x xor x shl 25

x = x xor x shr 27

gen.state = x

result = uint32((x * C) shr 32)

func nextFloat(gen: var XorShift): float =

gen.nextInt().float / float(0xFFFFFFFFu32)

when isMainModule:

var gen: XorShift

gen.seed(1234567)

for _ in 1..5:

echo gen.nextInt()

echo ""

gen.seed(987654321)

var counts: CountTable[int]

for _ in 1..100_000:

counts.inc int(gen.nextFloat() * 5)

echo sorted(toSeq(counts.pairs)).mapIt($it[0] & ": " & $it[1]).join(", ")</lang>

{{out}}

<pre>3540625527

2750739987

4037983143

1993361440

3809424708

0: 20103, 1: 19922, 2: 19937, 3: 20031, 4: 20007</pre>