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|
{-# OPTIONS_GHC -W #-}
import Data.Int
import Data.Packed
import Data.Packed.ST
import Control.Monad.ST
import Foreign.Storable
import Foreign.Ptr
import Foreign.Marshal.Utils
main :: IO ()
main = print $ arst (zeroMatrix 10 10) (Constant 9)
data ComputeElement
= Constant !Double
| Value !Double
deriving (Eq)
isConstant (Constant _) = True
isConstant _ = False
instance Element ComputeElement
fromComputeElement (Constant v) = v
fromComputeElement (Value v) = v
sizeofDouble = sizeOf (undefined :: Double)
sizeofInt64 = sizeOf (undefined :: Int64)
instance Storable ComputeElement where
sizeOf _ = sizeofDouble + sizeofInt64
alignment _ = 16
peek p = do
v <- peek (castPtr p)
c <- peek (castPtr (p `plusPtr` sizeofDouble))
return $ if toBool (c :: Int64)
then Constant v
else Value v
poke p v = do
let c :: Int64
c = fromBool (isConstant v)
poke (castPtr p) (fromComputeElement v)
poke (castPtr p `plusPtr` sizeofDouble) c
arst mat v = runST $ do
mat' <- thawMatrix mat
writeMatrix mat' 1 2 v
x <- fromComputeElement `fmap` readMatrix mat' 1 9
return (x > 0)
zeroMatrix m n = buildMatrix m n (const (Value 0))
|
