The problem disapears when I use GHC to compile the c file, this somehow
allows the linker to find the __stginit_SortPoints3() function.
I don't really understand what GHC does differently from gcc at compile
time on c files.
Thank you for your time.
Yann Morvan
Yann Morvan wrote:
Hello,
I am calling a Haskell function from C using foreign export, it works
fine on the first call,
but as soon as I call it again I get:
internal error: stg_ap_pp_ret
and I am asked to report it as a bug.
I don't know how much detail I should give, so I'll just reproduce the
relevant code (excuse the clumsyness):
On the Haskell side:
module SortPoints3 where
[...]
data Vect2D = Vect2D {xx,yy :: CFloat} deriving Show
instance Storable Vect2D where
peek a = do
x <- peekElemOff (castPtr a) 0
y <- peekElemOff (castPtr a) 1
return (Vect2D x y)
poke a (Vect2D x y) = do
pokeElemOff (castPtr a) 0 x
pokeElemOff (castPtr a) 1 y
sizeOf a = let dummy = Vect2D 2.0 2.0 in
(sizeOf (xx dummy) + (sizeOf (yy dummy)))
alignment a = 4
[...]
foreign export ccall doIt :: (Ptr Vect2D) -> (Ptr Vect2D) -> CInt ->
CFloat -> IO ()
doIt :: (Ptr Vect2D) -> (Ptr Vect2D) -> CInt -> CFloat -> IO ()
doIt pointsPtr projectedPtr n t = do
points <- peekArray (fromIntegral n) pointsPtr
(sortedPoints, sortedProjections ) <- sortPoints t points
pokeArray pointsPtr sortedPoints
pokeArray projectedPtr sortedProjections
return ()
On the C side, the function is called from a callback function of the
OpenCV library.
I pass it pointers to the OpenCV CvPoint2D32f type, which is a simple
struct with two floats for coordinates.
I had to remove the call to hs_add_root as the linker (GHC's) couldn't
find __stginit_SortPoints3()
I tried the following:
foreign export ccall printIt :: CFloat -> IO ()
printIt :: CFloat -> IO ()
printIt f = putStr $ "\nTest\n" ++ (show f) ++ "\n"
this function has no problem when called several times from the same
location in the c code.
Please tell me what to fix if the error is on my side.
Thank you for your time,
Yann Morvan
_______________________________________________
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
