{-# 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 = forall a.
Int -> (a -> Ptr Word8 -> IO (Ptr Word8)) -> BoundedPrim a
boudedPrim (forall a b. (Integral a, Num b) => a -> b
fromIntegral CInt
len) forall a b. (a -> b) -> a -> b
$ \a
val Ptr Word8
ptr -> do
  CInt
size <- b -> Ptr Word8 -> IO CInt
act (forall a b. (Real a, Fractional b) => a -> b
realToFrac a
val) Ptr Word8
ptr
  forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (CInt
size forall a. Eq a => a -> a -> Bool
== -CInt
1) forall b c a. (b -> c) -> (a -> b) -> a -> c
.
    forall (m :: * -> *) a. MonadFail m => String -> m a
fail forall a b. (a -> b) -> a -> b
$ String
"Data.Double.Conversion.ByteString." forall a. [a] -> [a] -> [a]
++ String
func forall a. [a] -> [a] -> [a]
++
           String
": conversion failed (invalid precision requested)"
  forall (m :: * -> *) a. Monad m => a -> m a
return (Ptr Word8
ptr forall a b. Ptr a -> Int -> Ptr b
`plusPtr` (forall a b. (Integral a, Num b) => a -> b
fromIntegral CInt
size))