{-# LANGUAGE CPP #-}
module System.Random.SplitMix.Init (
initialSeed,
) where
import Data.Word (Word64)
#if defined(SPLITMIX_INIT_GHCJS) && __GHCJS__
import Data.Word (Word32)
#else
#if defined(SPLITMIX_INIT_C)
#else
import Data.Bits (xor)
import Data.Time.Clock.POSIX (getPOSIXTime)
#if !__GHCJS__
import System.CPUTime (cpuTimePrecision, getCPUTime)
#endif
#endif
#endif
initialSeed :: IO Word64
#if defined(SPLITMIX_INIT_GHCJS) && __GHCJS__
initialSeed = fmap fromIntegral initialSeedJS
foreign import javascript
"$r = Math.floor(Math.random()*0x100000000);"
initialSeedJS :: IO Word32
#else
#if defined(SPLITMIX_INIT_C)
initialSeed = initialSeedC
foreign import ccall "splitmix_init" initialSeedC :: IO Word64
#else
initialSeed = do
now <- getPOSIXTime
let timebits = truncate now :: Word64
#if __GHCJS__
let cpubits = 0
#else
cpu <- getCPUTime
let cpubits = fromIntegral (cpu `div` cpuTimePrecision) :: Word64
#endif
return $ timebits `xor` cpubits
#endif
#endif