crypton-1.0.2: Crypto/Internal/ByteArray.hs

{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_HADDOCK hide #-}

-- |
-- Module      : Crypto.Internal.ByteArray
-- License     : BSD-style
-- Maintainer  : Vincent Hanquez <vincent@snarc.org>
-- Stability   : stable
-- Portability : Good
--
-- Simple and efficient byte array types
module Crypto.Internal.ByteArray (
    module Data.ByteArray,
    module Data.ByteArray.Mapping,
    module Data.ByteArray.Encoding,
    constAllZero,
) where

import Data.ByteArray
import Data.ByteArray.Encoding
import Data.ByteArray.Mapping

import Data.Bits ((.|.))
import Data.Word (Word8)
import Foreign.Ptr (Ptr)
import Foreign.Storable (peekByteOff)

import Crypto.Internal.Compat (unsafeDoIO)

constAllZero :: ByteArrayAccess ba => ba -> Bool
constAllZero b = unsafeDoIO $ withByteArray b $ \p -> loop p 0 0
  where
    loop :: Ptr b -> Int -> Word8 -> IO Bool
    loop p i !acc
        | i == len = return $! acc == 0
        | otherwise = do
            e <- peekByteOff p i
            loop p (i + 1) (acc .|. e)
    len = Data.ByteArray.length b