{-# LANGUAGE ConstraintKinds             #-}
{-# LANGUAGE DataKinds                   #-}
{-# LANGUAGE KindSignatures              #-}
{-# LANGUAGE MultiParamTypeClasses       #-}
{-# LANGUAGE FlexibleInstances           #-}
{-# LANGUAGE TypeFamilies                #-}
{-# LANGUAGE CPP                         #-}

-- |
--
-- Module      : indef:Implementation
-- Copyright   : (c) Piyush P Kurur, 2019
-- License     : Apache-2.0 OR BSD-3-Clause
-- Maintainer  : Piyush P Kurur <ppk@iitpkd.ac.in>
-- Stability   : experimental
--
-- This signature give the interface through which a cryptographic
-- bulk primitive, like cryptographic hash or a cipher is
-- implemented. The main interface is through the `processBlocks`
-- which gives the method to process data that is multiples of its
-- block size. The last chuck of data might not be a full multiple of
-- blocks in which case the `processLast` takes care of handling
-- it. Fast implementations involve other details like the alignment
-- restriction on the input buffer and all that. We package all this
-- in the following signature.
signature Implementation where

import Raaz.Core

# if MIN_VERSION_base(4,13,0)

import GHC.TypeLits

# endif


-- | Name of the implementation.
name :: String

-- | Description of the implementation.
description :: String

-- | The primitive for which the implementation is given
data Prim

-- | The internal memory used by the implementation.
data Internals

instance Primitive Prim
instance Memory Internals


# if MIN_VERSION_base(4,13,0)

-- | The alignment requirements on the buffer.
data BufferAlignment :: Nat
instance KnownNat BufferAlignment

# else
-- | The alignment required for buffer (hack around bug
-- https://ghc.haskell.org/trac/ghc/ticket/15138)
type BufferAlignment = 32
#endif

-- | The pointer type associated with the buffer used by the
-- implementation.
type BufferPtr = AlignedBlockPtr BufferAlignment Prim

-- | The additional space other than the payload that required in the
-- buffer for processing the data. There are multiple reasons for
-- having this additional space. The most important case is for
-- handling padding when processing the last block. Some fast
-- implementations, particularly those which use SIMD instructions,
-- handle data that is often a multiple of the block size. In such
-- cases, it make sense to have additional blocks in such cases to
-- make the overall implementation simple.
additionalBlocks :: BlockCount Prim

-- | The function that process bytes in multiples of the block size of
-- the primitive.
processBlocks :: BufferPtr
              -> BlockCount Prim
              -> Internals
              -> IO ()

-- | Process the last bytes of the stream.
processLast :: BufferPtr
            -> BYTES Int
            -> Internals
            -> IO ()