{-# LANGUAGE CPP                        #-}
{-# LANGUAGE DeriveDataTypeable         #-}
{-# LANGUAGE DeriveGeneric              #-}
{-# LANGUAGE FlexibleInstances          #-}
{-# LANGUAGE ForeignFunctionInterface   #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE RankNTypes                 #-}
{-# LANGUAGE TypeFamilies               #-}
#if __GLASGOW_HASKELL__ >= 707
{-# LANGUAGE RoleAnnotations            #-}
#endif
-- |
-- Module     : System.Random.PCG.Fast
-- Copyright  : Copyright (c) 2014-2015, Christopher Chalmers <c.chalmers@me.com>
-- License    : BSD3
-- Maintainer : Christopher Chalmers <c.chalmers@me.com>
-- Stability  : experimental
-- Portability: CPP, FFI
--
-- Fast variant of the PCG random number generator. This module performs
-- around 20% faster than the multiple streams version but produces slightly
-- lower quality (still good) random numbers.
--
-- See <http://www.pcg-random.org> for details.
--
-- @
-- import Control.Monad.ST
-- import System.Random.PCG.Fast
--
-- three :: [Double]
-- three = runST $ do
--   g <- create
--   a <- uniform g
--   b <- uniform g
--   c <- uniform g
--   return [a,b,c]
-- @
module System.Random.PCG.Fast
  ( -- * Gen
    Gen, GenIO, GenST
  , create, createSystemRandom, initialize
  , withSystemRandom, withFrozen

    -- * Getting random numbers
  , Variate (..)
  , advance, retract

    -- * Seeds
  , FrozenGen, save, restore, seed, initFrozen

    -- * Type restricted versions
    -- ** uniform
  , uniformW8, uniformW16, uniformW32, uniformW64
  , uniformI8, uniformI16, uniformI32, uniformI64
  , uniformF, uniformD, uniformBool

    -- ** uniformR
  , uniformRW8, uniformRW16, uniformRW32, uniformRW64
  , uniformRI8, uniformRI16, uniformRI32, uniformRI64
  , uniformRF, uniformRD, uniformRBool

    -- ** uniformB
  , uniformBW8, uniformBW16, uniformBW32, uniformBW64
  , uniformBI8, uniformBI16, uniformBI32, uniformBI64
  , uniformBF, uniformBD, uniformBBool
  ) where

import Control.Applicative
import Control.Monad.Primitive
import Control.Monad.ST
import Data.Data
import Foreign
import GHC.Generics
import System.IO.Unsafe
import System.Random

import System.Random.PCG.Class

-- $setup
-- >>> import System.Random.PCG.Fast
-- >>> import System.Random.PCG.Class
-- >>> import Control.Monad

------------------------------------------------------------------------
-- Seed
------------------------------------------------------------------------

-- | Immutable state of a random number generator. Suitable for storing
--   for later use.
newtype FrozenGen = FrozenGen Word64
  deriving (Int -> FrozenGen -> ShowS
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-- | Save the state of a 'Gen' in a 'Seed'.
save :: PrimMonad m => Gen (PrimState m) -> m FrozenGen
save :: Gen (PrimState m) -> m FrozenGen
save (Gen Ptr FrozenGen
p) = IO FrozenGen -> m FrozenGen
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(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (Ptr FrozenGen -> IO FrozenGen
forall a. Storable a => Ptr a -> IO a
peek Ptr FrozenGen
p)
{-# INLINE save #-}

-- | Restore a 'Gen' from a 'Seed'.
restore :: PrimMonad m => FrozenGen -> m (Gen (PrimState m))
restore :: FrozenGen -> m (Gen (PrimState m))
restore FrozenGen
s = IO (Gen (PrimState m)) -> m (Gen (PrimState m))
forall (m1 :: * -> *) (m2 :: * -> *) a.
(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (IO (Gen (PrimState m)) -> m (Gen (PrimState m)))
-> IO (Gen (PrimState m)) -> m (Gen (PrimState m))
forall a b. (a -> b) -> a -> b
$ do
  Ptr FrozenGen
p <- IO (Ptr FrozenGen)
forall a. Storable a => IO (Ptr a)
malloc
  Ptr FrozenGen -> FrozenGen -> IO ()
forall a. Storable a => Ptr a -> a -> IO ()
poke Ptr FrozenGen
p FrozenGen
s
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forall (m :: * -> *) a. Monad m => a -> m a
return (Ptr FrozenGen -> Gen (PrimState m)
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p)
{-# INLINE restore #-}

-- | Generate a new seed using single 'Word64'.
--
--   >>> initFrozen 0
--   FrozenGen 1
initFrozen :: Word64 -> FrozenGen
initFrozen :: Word64 -> FrozenGen
initFrozen Word64
w = IO FrozenGen -> FrozenGen
forall a. IO a -> a
unsafeDupablePerformIO (IO FrozenGen -> FrozenGen) -> IO FrozenGen -> FrozenGen
forall a b. (a -> b) -> a -> b
$ do
  Ptr FrozenGen
p <- IO (Ptr FrozenGen)
forall a. Storable a => IO (Ptr a)
malloc
  Ptr FrozenGen -> Word64 -> IO ()
pcg32f_srandom_r Ptr FrozenGen
p Word64
w
  Ptr FrozenGen -> IO FrozenGen
forall a. Storable a => Ptr a -> IO a
peek Ptr FrozenGen
p IO FrozenGen -> IO () -> IO FrozenGen
forall (f :: * -> *) a b. Applicative f => f a -> f b -> f a
<* Ptr FrozenGen -> IO ()
forall a. Ptr a -> IO ()
free Ptr FrozenGen
p
{-# INLINE initFrozen #-}

-- | Standard initial seed.
seed :: FrozenGen
seed :: FrozenGen
seed = Word64 -> FrozenGen
FrozenGen Word64
0xcafef00dd15ea5e5

-- | Create a 'Gen' from a fixed initial seed.
create :: PrimMonad m => m (Gen (PrimState m))
create :: m (Gen (PrimState m))
create = FrozenGen -> m (Gen (PrimState m))
forall (m :: * -> *).
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FrozenGen -> m (Gen (PrimState m))
restore FrozenGen
seed

------------------------------------------------------------------------
-- Gen
------------------------------------------------------------------------

-- | State of the random number generator
newtype Gen s = Gen (Ptr FrozenGen)
  deriving (Gen s -> Gen s -> Bool
(Gen s -> Gen s -> Bool) -> (Gen s -> Gen s -> Bool) -> Eq (Gen s)
forall s. Gen s -> Gen s -> Bool
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#if __GLASGOW_HASKELL__ >= 707
type role Gen representational
#endif

type GenIO = Gen RealWorld
type GenST = Gen

-- | Initialize a generator a single word.
--
--   >>> initialize 0 >>= save
--   FrozenGen 1
initialize :: PrimMonad m => Word64 -> m (Gen (PrimState m))
initialize :: Word64 -> m (Gen (PrimState m))
initialize Word64
a = IO (Gen (PrimState m)) -> m (Gen (PrimState m))
forall (m1 :: * -> *) (m2 :: * -> *) a.
(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (IO (Gen (PrimState m)) -> m (Gen (PrimState m)))
-> IO (Gen (PrimState m)) -> m (Gen (PrimState m))
forall a b. (a -> b) -> a -> b
$ do
  Ptr FrozenGen
p <- IO (Ptr FrozenGen)
forall a. Storable a => IO (Ptr a)
malloc
  Ptr FrozenGen -> Word64 -> IO ()
pcg32f_srandom_r Ptr FrozenGen
p Word64
a
  Gen (PrimState m) -> IO (Gen (PrimState m))
forall (m :: * -> *) a. Monad m => a -> m a
return  (Ptr FrozenGen -> Gen (PrimState m)
forall s. Ptr FrozenGen -> Gen s
Gen Ptr FrozenGen
p)

-- | Seed with system random number. (@\/dev\/urandom@ on Unix-like
--   systems and CryptAPI on Windows).
withSystemRandom :: (GenIO -> IO a) -> IO a
withSystemRandom :: (GenIO -> IO a) -> IO a
withSystemRandom GenIO -> IO a
f = do
  Word64
w <- IO Word64
sysRandom
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forall (m :: * -> *).
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Word64 -> m (Gen (PrimState m))
initialize Word64
w IO GenIO -> (GenIO -> IO a) -> IO a
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= GenIO -> IO a
f

-- | Run an action with a frozen generator, returning the result and the
--   new frozen generator.
withFrozen :: FrozenGen -> (forall s. Gen s -> ST s a) -> (a, FrozenGen)
withFrozen :: FrozenGen -> (forall s. Gen s -> ST s a) -> (a, FrozenGen)
withFrozen FrozenGen
s forall s. Gen s -> ST s a
f = (forall s. ST s (a, FrozenGen)) -> (a, FrozenGen)
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restore FrozenGen
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g -> (a -> FrozenGen -> (a, FrozenGen))
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forall s. Gen s -> ST s a
f Gen s
g) (Gen (PrimState (ST s)) -> ST s FrozenGen
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save Gen s
Gen (PrimState (ST s))
g)

-- | Seed a PRNG with data from the system's fast source of pseudo-random
-- numbers. All the caveats of 'withSystemRandom' apply here as well.
createSystemRandom :: IO GenIO
createSystemRandom :: IO GenIO
createSystemRandom = (GenIO -> IO GenIO) -> IO GenIO
forall a. (GenIO -> IO a) -> IO a
withSystemRandom (GenIO -> IO GenIO
forall (m :: * -> *) a. Monad m => a -> m a
return :: GenIO -> IO GenIO)

-- | Advance the given generator n steps in log(n) time. (Note that a
--   \"step\" is a single random 32-bit (or less) 'Variate'. Data types
--   such as 'Double' or 'Word64' require two \"steps\".)
--
--   >>> create >>= \g -> replicateM_ 1000 (uniformW32 g) >> uniformW32 g
--   3725702568
--   >>> create >>= \g -> replicateM_ 500 (uniformD g) >> uniformW32 g
--   3725702568
--   >>> create >>= \g -> advance 1000 g >> uniformW32 g
--   3725702568
advance :: PrimMonad m => Word64 -> Gen (PrimState m) -> m ()
advance :: Word64 -> Gen (PrimState m) -> m ()
advance Word64
u (Gen Ptr FrozenGen
p) = IO () -> m ()
forall (m1 :: * -> *) (m2 :: * -> *) a.
(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (IO () -> m ()) -> IO () -> m ()
forall a b. (a -> b) -> a -> b
$ Ptr FrozenGen -> Word64 -> IO ()
pcg32f_advance_r Ptr FrozenGen
p Word64
u
{-# INLINE advance #-}

-- | Retract the given generator n steps in log(2^64-n) time. This
--   is just @advance (-n)@.
--
--   >>> create >>= \g -> replicateM 3 (uniformW32 g)
--   [2951688802,2698927131,361549788]
--   >>> create >>= \g -> retract 1 g >> replicateM 3 (uniformW32 g)
--   [954135925,2951688802,2698927131]
retract :: PrimMonad m => Word64 -> Gen (PrimState m) -> m ()
retract :: Word64 -> Gen (PrimState m) -> m ()
retract Word64
u Gen (PrimState m)
g = Word64 -> Gen (PrimState m) -> m ()
forall (m :: * -> *).
PrimMonad m =>
Word64 -> Gen (PrimState m) -> m ()
advance (-Word64
u) Gen (PrimState m)
g
{-# INLINE retract #-}

------------------------------------------------------------------------
-- Foreign calls
------------------------------------------------------------------------

foreign import ccall unsafe "pcg_mcg_64_srandom_r"
  pcg32f_srandom_r :: Ptr FrozenGen -> Word64 -> IO ()

foreign import ccall unsafe "pcg_mcg_64_xsh_rs_32_random_r"
  pcg32f_random_r :: Ptr FrozenGen -> IO Word32

foreign import ccall unsafe "pcg_mcg_64_xsh_rs_32_boundedrand_r"
  pcg32f_boundedrand_r :: Ptr FrozenGen -> Word32 -> IO Word32

foreign import ccall unsafe "pcg_mcg_64_advance_r"
  pcg32f_advance_r :: Ptr FrozenGen -> Word64 -> IO ()

------------------------------------------------------------------------
-- Instances
------------------------------------------------------------------------

instance (PrimMonad m, s ~ PrimState m) => Generator (Gen s) m where
  uniform1 :: (Word32 -> a) -> Gen s -> m a
uniform1 Word32 -> a
f (Gen Ptr FrozenGen
p) = IO a -> m a
forall (m1 :: * -> *) (m2 :: * -> *) a.
(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (IO a -> m a) -> IO a -> m a
forall a b. (a -> b) -> a -> b
$ Word32 -> a
f (Word32 -> a) -> IO Word32 -> IO a
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
  {-# INLINE uniform1 #-}

  uniform2 :: (Word32 -> Word32 -> a) -> Gen s -> m a
uniform2 Word32 -> Word32 -> a
f (Gen Ptr FrozenGen
p) = IO a -> m a
forall (m1 :: * -> *) (m2 :: * -> *) a.
(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (IO a -> m a) -> IO a -> m a
forall a b. (a -> b) -> a -> b
$ do
    Word32
w1 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    Word32
w2 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (a -> IO a) -> a -> IO a
forall a b. (a -> b) -> a -> b
$ Word32 -> Word32 -> a
f Word32
w1 Word32
w2
  {-# INLINE uniform2 #-}

  uniform1B :: (Word32 -> a) -> Word32 -> Gen s -> m a
uniform1B Word32 -> a
f Word32
b (Gen Ptr FrozenGen
p) = IO a -> m a
forall (m1 :: * -> *) (m2 :: * -> *) a.
(PrimBase m1, PrimMonad m2) =>
m1 a -> m2 a
unsafePrimToPrim (IO a -> m a) -> IO a -> m a
forall a b. (a -> b) -> a -> b
$ Word32 -> a
f (Word32 -> a) -> IO Word32 -> IO a
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Ptr FrozenGen -> Word32 -> IO Word32
pcg32f_boundedrand_r Ptr FrozenGen
p Word32
b
  {-# INLINE uniform1B #-}

instance RandomGen FrozenGen where
  next :: FrozenGen -> (Int, FrozenGen)
next FrozenGen
s = IO (Int, FrozenGen) -> (Int, FrozenGen)
forall a. IO a -> a
unsafeDupablePerformIO (IO (Int, FrozenGen) -> (Int, FrozenGen))
-> IO (Int, FrozenGen) -> (Int, FrozenGen)
forall a b. (a -> b) -> a -> b
$ do
    Ptr FrozenGen
p <- IO (Ptr FrozenGen)
forall a. Storable a => IO (Ptr a)
malloc
    Ptr FrozenGen -> FrozenGen -> IO ()
forall a. Storable a => Ptr a -> a -> IO ()
poke Ptr FrozenGen
p FrozenGen
s
    Word32
w1 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    Word32
w2 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    FrozenGen
s' <- Ptr FrozenGen -> IO FrozenGen
forall a. Storable a => Ptr a -> IO a
peek Ptr FrozenGen
p
    Ptr FrozenGen -> IO ()
forall a. Ptr a -> IO ()
free Ptr FrozenGen
p
    (Int, FrozenGen) -> IO (Int, FrozenGen)
forall (m :: * -> *) a. Monad m => a -> m a
return (Word32 -> Word32 -> Int
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit Word32
w1 Word32
w2, FrozenGen
s')
  {-# INLINE next #-}

  split :: FrozenGen -> (FrozenGen, FrozenGen)
split FrozenGen
s = IO (FrozenGen, FrozenGen) -> (FrozenGen, FrozenGen)
forall a. IO a -> a
unsafeDupablePerformIO (IO (FrozenGen, FrozenGen) -> (FrozenGen, FrozenGen))
-> IO (FrozenGen, FrozenGen) -> (FrozenGen, FrozenGen)
forall a b. (a -> b) -> a -> b
$ do
    Ptr FrozenGen
p  <- IO (Ptr FrozenGen)
forall a. Storable a => IO (Ptr a)
malloc
    Ptr FrozenGen -> FrozenGen -> IO ()
forall a. Storable a => Ptr a -> a -> IO ()
poke Ptr FrozenGen
p FrozenGen
s
    Word32
w1 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    Word32
w2 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    Word32
w3 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    Word32
w4 <- Ptr FrozenGen -> IO Word32
pcg32f_random_r Ptr FrozenGen
p
    Ptr FrozenGen -> Word64 -> IO ()
pcg32f_srandom_r Ptr FrozenGen
p (Word32 -> Word32 -> Word64
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit Word32
w1 Word32
w2)
    FrozenGen
s1 <- Ptr FrozenGen -> IO FrozenGen
forall a. Storable a => Ptr a -> IO a
peek Ptr FrozenGen
p
    Ptr FrozenGen -> Word64 -> IO ()
pcg32f_srandom_r Ptr FrozenGen
p (Word32 -> Word32 -> Word64
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit Word32
w3 Word32
w4)
    FrozenGen
s2 <- Ptr FrozenGen -> IO FrozenGen
forall a. Storable a => Ptr a -> IO a
peek Ptr FrozenGen
p
    Ptr FrozenGen -> IO ()
forall a. Ptr a -> IO ()
free Ptr FrozenGen
p
    (FrozenGen, FrozenGen) -> IO (FrozenGen, FrozenGen)
forall (m :: * -> *) a. Monad m => a -> m a
return (FrozenGen
s1,FrozenGen
s2)