{-# LANGUAGE ForeignFunctionInterface #-}
module Crypto.Random.Entropy.RDRand
( RDRand
) where
import Foreign.Ptr
import Foreign.C.Types
import Data.Word (Word8)
import Crypto.Random.Entropy.Source
foreign import ccall unsafe "cryptonite_cpu_has_rdrand"
c_cpu_has_rdrand :: IO CInt
foreign import ccall unsafe "cryptonite_get_rand_bytes"
c_get_rand_bytes :: Ptr Word8 -> CInt -> IO CInt
data RDRand = RDRand
instance EntropySource RDRand where
entropyOpen = rdrandGrab
entropyGather _ = rdrandGetBytes
entropyClose _ = return ()
rdrandGrab :: IO (Maybe RDRand)
rdrandGrab = supported `fmap` c_cpu_has_rdrand
where supported 0 = Nothing
supported _ = Just RDRand
rdrandGetBytes :: Ptr Word8 -> Int -> IO Int
rdrandGetBytes ptr sz = fromIntegral `fmap` c_get_rand_bytes ptr (fromIntegral sz)