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

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

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 :: forall ba. ByteArrayAccess ba => ba -> Bool
constAllZero ba
b = IO Bool -> Bool
forall a. IO a -> a
unsafeDoIO (IO Bool -> Bool) -> IO Bool -> Bool
forall a b. (a -> b) -> a -> b
$ ba -> (Ptr Any -> IO Bool) -> IO Bool
forall ba p a. ByteArrayAccess ba => ba -> (Ptr p -> IO a) -> IO a
forall p a. ba -> (Ptr p -> IO a) -> IO a
withByteArray ba
b ((Ptr Any -> IO Bool) -> IO Bool)
-> (Ptr Any -> IO Bool) -> IO Bool
forall a b. (a -> b) -> a -> b
$ \Ptr Any
p -> Ptr Any -> Int -> Word8 -> IO Bool
forall b. Ptr b -> Int -> Word8 -> IO Bool
loop Ptr Any
p Int
0 Word8
0
  where
    loop :: Ptr b -> Int -> Word8 -> IO Bool
    loop :: forall b. Ptr b -> Int -> Word8 -> IO Bool
loop Ptr b
p Int
i !Word8
acc
        | Int
i Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
len  = Bool -> IO Bool
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (Bool -> IO Bool) -> Bool -> IO Bool
forall a b. (a -> b) -> a -> b
$! Word8
acc Word8 -> Word8 -> Bool
forall a. Eq a => a -> a -> Bool
== Word8
0
        | Bool
otherwise = do
            Word8
e <- Ptr b -> Int -> IO Word8
forall b. Ptr b -> Int -> IO Word8
forall a b. Storable a => Ptr b -> Int -> IO a
peekByteOff Ptr b
p Int
i
            Ptr b -> Int -> Word8 -> IO Bool
forall b. Ptr b -> Int -> Word8 -> IO Bool
loop Ptr b
p (Int
iInt -> Int -> Int
forall a. Num a => a -> a -> a
+Int
1) (Word8
acc Word8 -> Word8 -> Word8
forall a. Bits a => a -> a -> a
.|. Word8
e)
    len :: Int
len = ba -> Int
forall ba. ByteArrayAccess ba => ba -> Int
Data.ByteArray.length ba
b