{-# LANGUAGE GADTs               #-}
{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications    #-}
-- |
-- Module      : Data.Array.Accelerate.LLVM.PTX.CodeGen.Map
-- Copyright   : [2014..2020] The Accelerate Team
-- License     : BSD3
--
-- Maintainer  : Trevor L. McDonell <trevor.mcdonell@gmail.com>
-- Stability   : experimental
-- Portability : non-portable (GHC extensions)
--

module Data.Array.Accelerate.LLVM.PTX.CodeGen.Map
  where

-- accelerate
import Data.Array.Accelerate.Representation.Array
import Data.Array.Accelerate.Representation.Type
import Data.Array.Accelerate.Type

import Data.Array.Accelerate.LLVM.CodeGen.Arithmetic
import Data.Array.Accelerate.LLVM.CodeGen.Array
import Data.Array.Accelerate.LLVM.CodeGen.Base
import Data.Array.Accelerate.LLVM.CodeGen.Environment
import Data.Array.Accelerate.LLVM.CodeGen.Exp
import Data.Array.Accelerate.LLVM.CodeGen.Monad
import Data.Array.Accelerate.LLVM.CodeGen.Sugar

import Data.Array.Accelerate.LLVM.PTX.CodeGen.Base
import Data.Array.Accelerate.LLVM.PTX.CodeGen.Loop
import Data.Array.Accelerate.LLVM.PTX.Target                    ( PTX )


-- Apply a unary function to each element of an array. Each thread processes
-- multiple elements, striding the array by the grid size.
--
mkMap :: Gamma       aenv
      -> ArrayR (Array sh a)
      -> TypeR b
      -> IRFun1  PTX aenv (a -> b)
      -> CodeGen PTX      (IROpenAcc PTX aenv (Array sh b))
mkMap aenv repr@(ArrayR shr _) tp' apply =
  let
      (arrOut, paramOut)  = mutableArray (ArrayR shr tp') "out"
      (arrIn,  paramIn)   = mutableArray repr             "in"
      paramEnv            = envParam aenv
  in
  makeOpenAcc "map" (paramOut ++ paramIn ++ paramEnv) $ do

    start <- return (liftInt 0)
    end   <- shapeSize shr (irArrayShape arrIn)

    imapFromTo start end $ \i -> do
      xs <- readArray TypeInt arrIn i
      ys <- app1 apply xs
      writeArray TypeInt arrOut i ys

    return_