{-# LANGUAGE TypeFamilies, TypeOperators #-}

-- |
-- Module      : Data.Double.Conversion.ByteStringBuilder
-- Copyright   : (c) 2011 MailRank, Inc.
--
-- License     : BSD-style
-- Maintainer  : bos@serpentine.com
-- Stability   : experimental
-- Portability : GHC
--
-- Fast, efficient support for converting between double precision
-- floating point values and bytestring builder.

module Data.Double.Conversion.Internal.ByteStringBuilder
    (convert
    ) where

import Control.Monad (when)

import Data.ByteString.Builder.Prim.Internal (BoundedPrim, boudedPrim)

import Data.Double.Conversion.Internal.FFI (ForeignFloating)
import Data.Word (Word8)
import Foreign.C.Types (CDouble, CFloat, CInt)
import Foreign.Ptr (Ptr, plusPtr)

convert :: (RealFloat a, RealFloat b , b ~ ForeignFloating a) => String -> CInt -> (b -> Ptr Word8 -> IO CInt) -> BoundedPrim a
{-# SPECIALIZE convert :: String -> CInt -> (CDouble -> Ptr Word8 -> IO CInt) -> BoundedPrim Double #-}
{-# SPECIALIZE convert :: String -> CInt -> (CFloat -> Ptr Word8 -> IO CInt) -> BoundedPrim Float #-}
{-# INLINABLE convert #-}
convert :: forall a b.
(RealFloat a, RealFloat b, b ~ ForeignFloating a) =>
String -> CInt -> (b -> Ptr Word8 -> IO CInt) -> BoundedPrim a
convert String
func CInt
len b -> Ptr Word8 -> IO CInt
act = Int -> (a -> Ptr Word8 -> IO (Ptr Word8)) -> BoundedPrim a
forall a.
Int -> (a -> Ptr Word8 -> IO (Ptr Word8)) -> BoundedPrim a
boudedPrim (CInt -> Int
forall a b. (Integral a, Num b) => a -> b
fromIntegral CInt
len) ((a -> Ptr Word8 -> IO (Ptr Word8)) -> BoundedPrim a)
-> (a -> Ptr Word8 -> IO (Ptr Word8)) -> BoundedPrim a
forall a b. (a -> b) -> a -> b
$ \a
val Ptr Word8
ptr -> do
  size <- b -> Ptr Word8 -> IO CInt
act (a -> b
forall a b. (Real a, Fractional b) => a -> b
realToFrac a
val) Ptr Word8
ptr
  when (size == -1) .
    fail $ "Data.Double.Conversion.ByteString." ++ func ++
           ": conversion failed (invalid precision requested)"
  return (ptr `plusPtr` (fromIntegral size))