> (vlong)(...|((p)[3]<<24)) sign extends. Casting the (p)[0] > to (ulong) has the effect of making the whole 32-bit expression > unsigned on 32-bit systems, but if ulong is 64 bits, then > you'll still sign-extend ((p)[3]<<24) during the convertsion > from int to ulong.
i'd be careful to define ulong to be 32 bits for all plan 9 source including p9p (using `ulong == unsigned int' if necessary). otherwise quite a bit more will break. having fcall.h use u32int is fine too, of course, just to make the point clearer
