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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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Task/Pseudo-random-numbers-PCG32/Haskell/pseudo-random-numbers-pcg32.hs Normal file
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import Data.Bits
import Data.Word
import System.Random
import Data.List
data PCGen = PCGen !Word64 !Word64
mkPCGen state sequence =
let
n = 6364136223846793005 :: Word64
inc = (sequence `shiftL` 1) .|. 1 :: Word64
in PCGen ((inc + state)*n + inc) inc
instance RandomGen PCGen where
next (PCGen state inc) =
let
n = 6364136223846793005 :: Word64
xs = fromIntegral $ ((state `shiftR` 18) `xor` state) `shiftR` 27 :: Word32
rot = fromIntegral $ state `shiftR` 59 :: Int
in (fromIntegral $ (xs `shiftR` rot) .|. (xs `shiftL` ((-rot) .&. 31))
, PCGen (state * n + inc) inc)
split _ = error "PCG32 is not splittable"
randoms' :: RandomGen g => g -> [Int]
randoms' g = unfoldr (pure . next) g
toFloat n = fromIntegral n / (2^32 - 1)