Hi Haskell hackers, We start trying to rewrite NetBSD kernel using Haskell language. https://github.com/metasepi/netbsd-arafura-s1 But we find some problems. Could you have any ideas for them? ## Status * Trying rewrite AC''97 sound driver using Haskell * Before rewriting. (C language) https://github.com/metasepi/netbsd-arafura-s1/blob/d1b19c686de5573ef8a8342a3... * After rewriting. (Haskell language) https://github.com/metasepi/netbsd-arafura-s1/blob/d1b19c686de5573ef8a8342a3... * Have rewrited 2 functions, auich_open() and auich_close() * Not yet touch Haskell heap ## Problems Some time, C programmer writes following code. ~~~ static int auich_open(void *addr, int flags) { struct auich_softc *sc; sc = (struct auich_softc *)addr; mutex_spin_exit(&sc->sc_intr_lock); sc->codec_if->vtbl->lock(sc->codec_if); ~~~ Note the line "sc->codec_if->vtbl->lock(sc->codec_if);". It traces pointer tree regionally. Haskell's Strorable class is not good for the use case, because it copies the entire pointer tree! We avoid the problem using following messy code. https://github.com/metasepi/netbsd-arafura-s1/blob/d1b19c686de5573ef8a8342a3... ~~~ auichOpen :: Ptr AuichSoftc -> Int -> IO Int auichOpen sc flags = do mutexp <- p_AuichSoftc_sc_intr_lock sc codeif <- peek =<< p_AuichSoftc_codec_if sc lock <- peek =<< p_Ac97CodecIfVtbl_lock =<< peek =<< p_Ac97CodecIf_vtbl codeif mutexSpinExit mutexp call_Ac97CodecIfVtbl_lock lock codeif -- snip -- p_AuichSoftc_sc_intr_lock :: Ptr AuichSoftc -> IO (Ptr KmutexT) p_AuichSoftc_sc_intr_lock p = return $ plusPtr p offsetOf_AuichSoftc_sc_intr_lock p_AuichSoftc_codec_if :: Ptr AuichSoftc -> IO (Ptr (Ptr Ac97CodecIf)) p_AuichSoftc_codec_if p = return $ plusPtr p offsetOf_AuichSoftc_codec_if p_Ac97CodecIf_vtbl :: Ptr Ac97CodecIf -> IO (Ptr (Ptr Ac97CodecIfVtbl)) p_Ac97CodecIf_vtbl p = return $ plusPtr p offsetOf_Ac97CodecIf_vtbl p_Ac97CodecIfVtbl_lock :: Ptr Ac97CodecIfVtbl -> IO (Ptr (FunPtr Ac97CodecIfVtbl_lock)) p_Ac97CodecIfVtbl_lock p = return $ plusPtr p offsetOf_Ac97CodecIfVtbl_lock ~~~ Haskell world has the answer for it already? Best regards, -- Kiwamu Okabe