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|
{-# LANGUAGE BangPatterns #-}
-- |
-- Module : Crypto.Internal.Builder
-- License : BSD-style
-- Maintainer : Olivier Chéron <olivier.cheron@gmail.com>
-- Stability : stable
-- Portability : Good
--
-- Delaying and merging ByteArray allocations. This is similar to module
-- "Data.ByteArray.Pack" except the total length is computed automatically based
-- on what is appended.
module Crypto.Internal.Builder (
Builder,
buildAndFreeze,
builderLength,
byte,
bytes,
zero,
) where
import Data.ByteArray (ByteArray, ByteArrayAccess)
import qualified Data.ByteArray as B
import Data.Memory.PtrMethods (memSet)
import Foreign.Ptr (Ptr, plusPtr)
import Foreign.Storable (poke)
import Crypto.Internal.Imports hiding (empty)
data Builder = Builder !Int (Ptr Word8 -> IO ()) -- size and initializer
instance Semigroup Builder where
(Builder s1 f1) <> (Builder s2 f2) = Builder (s1 + s2) f
where
f p = f1 p >> f2 (p `plusPtr` s1)
builderLength :: Builder -> Int
builderLength (Builder s _) = s
buildAndFreeze :: ByteArray ba => Builder -> ba
buildAndFreeze (Builder s f) = B.allocAndFreeze s f
byte :: Word8 -> Builder
byte !b = Builder 1 (`poke` b)
bytes :: ByteArrayAccess ba => ba -> Builder
bytes bs = Builder (B.length bs) (B.copyByteArrayToPtr bs)
zero :: Int -> Builder
zero s = if s > 0 then Builder s (\p -> memSet p 0 s) else empty
empty :: Builder
empty = Builder 0 (const $ return ())
|
