Here's my situation:
I would like to call ffmpeg's av_free_packet
function:
// avformat.h
static inline void av_free_packet(AVPacket *pkt)
{
if (pkt && pkt->destruct)
pkt->destruct(pkt);
}
But unfortunately this function is static inline
, and so doesn't really appear in the linked library.
However, it is a very simple function, which I could reimplement in Haskell. And that's what I can't figure out how to do. Here's a partial attempt (.hsc):
av_free_packet :: Ptr AVPacket -> IO ()
av_free_packet pkt =
when (nullPtr /= pkt) $ do
destruct <- (#peek AVPacket, destruct) pkt :: IO (FunPtr (Ptr AVPacket -> IO ()))
when (nullFunPtr /= destruct) $ funPtrToFun destruct pkt
funPtrToFun :: FunPtr a -> a
funPtrToFun = ?
For now I could resort to implementing this function in C (by just calling the original), but it seems to me that calling function pointers should be possible somehow..