5 files changed, 122 insertions, 0 deletions
diff --git a/test/Examples/Mandel.hs b/test/Examples/Mandel.hs
new file mode 100644
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+++ b/test/Examples/Mandel.hs
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+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE ViewPatterns #-}
+module Examples.Mandel (afun) where
+
+import Prelude ()
+import qualified Prelude as P
+import Data.Array.Accelerate
+
+
+type Dims = (Int, Int)
+type Pos = (Double, Double)
+type Viewport = (Dims     -- image size
+                ,Pos      -- midpoint
+                ,Double)  -- complex width of the viewport
+
+type RGB = (Word8, Word8, Word8)
+
+-- Arguments: viewport and maxiter
+-- Result: image in row-major order
+afun :: Acc (Scalar (Viewport, Int)) -> Acc (Matrix RGB)
+afun (the -> T2 viewport maxiter) = mandel viewport maxiter (clrBasic maxiter)
+
+clrBasic :: Exp Int -> Exp Int -> Exp RGB
+clrBasic maxiterI nI =
+    let maxiter = log (toFloating maxiterI)
+        n = log (toFloating nI)
+    in cond (n == maxiter)
+            (T3 0 0 0)
+            (let r = slope (Just (maxiter / 4)) Nothing n maxiter
+                 g = slope Nothing Nothing n maxiter
+                 b = slope Nothing (Just (maxiter * 3 / 4)) n maxiter
+             in T3 r g b)
+  where
+    slope :: Maybe (Exp Double) -> Maybe (Exp Double) -> Exp Double -> Exp Double -> Exp Word8
+    slope mlo mhi x m =
+        (P.maybe ($ 0) (\lo' -> max 0 . ($ lo')) mlo) $ \lo ->
+        (P.maybe ($ m) (\hi' -> min 255 . ($ hi')) mhi) $ \hi ->
+            fromIntegral @Int @Word8 $ round @Double @Int $
+                max 0 $ min 255 $ (x - lo) * 255 / (hi - lo)
+
+mandel :: Exp Viewport -> Exp Int -> (Exp Int -> Exp RGB) -> Acc (Matrix RGB)
+mandel (T3 (T2 w h) (T2 cx cy) cw) maxiter clrscheme =
+    generate (I2 h w) $ \(I2 yi xi) ->
+        let minx = cx - cw / 2
+            ch = toFloating h / toFloating w * cw
+            maxy = cy + ch / 2
+            x = minx + toFloating xi / (toFloating w - 1) * cw
+            y = maxy - toFloating yi / (toFloating h - 1) * ch
+        in clrscheme (mandeliter x y maxiter)
+
+mandeliter :: Exp Double -> Exp Double -> Exp Int -> Exp Int
+mandeliter x y maxiter =
+    let T5 _ _ _ _ n =
+            while (\(T5 _ _ a2 b2 i) -> a2 + b2 < 4 && i < maxiter)
+                  (\(T5 a b a2 b2 i) ->
+                      let a' = a2 - b2 + x
+                          b' = 2 * a * b + y
+                      in T5 a' b' (a'*a') (b'*b') (i + 1))
+                  (T5 x y (x*x) (y*y) 0)
+    in n
diff --git a/test/Examples/Mandel/Main.hs b/test/Examples/Mandel/Main.hs
new file mode 100644
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+++ b/test/Examples/Mandel/Main.hs
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+module Examples.Mandel.Main where
+
+import qualified Data.Array.Accelerate as A
+import qualified Data.Array.Accelerate.Interpreter as I
+
+import qualified Examples.Mandel as Mandel
+import Examples.Utils.PPM
+
+
+main :: IO ()
+main = do
+    let viewport = ((640, 480), (-0.5, 0.0), 3.0)
+        img = I.run1 Mandel.afun (A.fromList A.Z [(viewport, 200)])
+    ppmWrite img "mandel.ppm"
diff --git a/test/Examples/Test.hs b/test/Examples/Test.hs
new file mode 100644
index 0000000..f3df311
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+++ b/test/Examples/Test.hs
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+module Examples.Test (afun) where
+
+import Data.Array.Accelerate
+
+
+afun :: Acc (Matrix Int, Vector (Int, Int))
+     -> Acc (Matrix Int)
+afun (T2 a b) = generate (I2 2 3) (\(I2 i j) ->
+                  let T2 x y = b ! I1 i
+                  in i * j + a ! I2 i j + x * y)
diff --git a/test/Examples/Utils/PPM.hs b/test/Examples/Utils/PPM.hs
new file mode 100644
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+++ b/test/Examples/Utils/PPM.hs
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+module Examples.Utils.PPM where
+
+import qualified Data.Array.Accelerate as A
+import Data.Word
+
+
+type RGB = (Word8, Word8, Word8)
+
+ppmWrite :: A.Matrix RGB -> FilePath -> IO ()
+ppmWrite img fp = do
+    let A.Z A.:. h A.:. w = A.arrayShape img
+        line y = unwords $ concat [[show r, show g, show b] | x <- [0 .. w - 1], let (r, g, b) = A.indexArray img (A.Z A.:. y A.:. x)]
+        contents = unlines $
+            ["P3"
+            ,show w ++ " " ++ show h
+            ,"255"]
+            ++ [line y | y <- [0 .. h - 1]]
+    writeFile fp contents
diff --git a/test/Main.hs b/test/Main.hs
new file mode 100644
index 0000000..19105dd
--- /dev/null
+++ b/test/Main.hs
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+module Main where
+
+import qualified Data.Array.Accelerate as A
+import qualified Data.Array.Accelerate.Interpreter as I
+import System.Exit
+
+import qualified Data.Array.Accelerate.C as C
+
+import qualified Examples.Mandel as Mandel
+import Examples.Utils.PPM
+
+
+main :: IO ()
+main = do
+    let viewport = ((640, 480), (-0.5, 0.0), 3.0)
+        img = I.run1 Mandel.afun (A.fromList A.Z [(viewport, 200)])
+    case C.translateAcc "mandelkernel" Mandel.afun of
+      Left err -> die err
+      Right (code, _, _) -> writeFile "mandel-out.c" code
+    ppmWrite img "mandel.ppm"