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|
module Data.Array.Repa.Stencil.Partition
( Offset (..)
, Size (..)
, Region (..)
, partitionForStencil)
where
-- | An offset in the 2d plane.
data Offset
= Offset !Int !Int
-- | Size of a region in the 2d plane.
data Size
= Size !Int !Int
-- | A region in the 2d plane.
data Region
= Region
{ regionX :: !Int
, regionY :: !Int
, regionWidth :: !Int
, regionHeight :: !Int }
deriving Show
-- | Create a new region of the given size.
regionOfSize :: Size -> Region
regionOfSize (Size w h)
= Region 0 0 w h
{-# INLINE regionOfSize #-}
-- | Offset a region.
offsetRegion :: Offset -> Region -> Region
offsetRegion (Offset x y) (Region x0 y0 w h)
= Region (x0 + x) (y0 + y) w h
{-# INLINE offsetRegion #-}
-- | Partition a region into inner and border regions for the given stencil.
partitionForStencil
:: Size -- ^ Size of array
-> Size -- ^ Size of stencil
-> Offset -- ^ Focus of stencil
-> [Region]
partitionForStencil
(Size arrW arrH)
(Size krnW krnH)
(Offset focX focY)
= let
gapNorth = focY
gapSouth = krnH - focY - 1
gapWest = focX
gapEast = krnW - focX - 1
innerW = arrW - gapWest - gapEast
innerH = arrH - gapNorth - gapSouth
regionInner = offsetRegion (Offset gapWest gapNorth)
$ regionOfSize (Size innerW innerH)
regionNorth = regionOfSize (Size arrW gapNorth)
regionSouth = offsetRegion (Offset 0 (gapNorth + innerH))
$ regionOfSize (Size arrW gapSouth)
regionWest = offsetRegion (Offset 0 gapNorth)
$ regionOfSize (Size gapWest innerH)
regionEast = offsetRegion (Offset (gapWest + innerW) gapNorth)
$ regionOfSize (Size gapEast innerH)
in [regionInner, regionNorth, regionSouth, regionWest, regionEast]
{-# INLINE partitionForStencil #-}
|
