That worked, thank you so much! I'm curious though, why does that work? By all rights that seems to basically be a no-op, due to it ending up with the same value it had before. Am I missing something, or is this just how Racket works?
On Jun 9, 2012, at 4:13 AM, Matthew Flatt <[email protected]> wrote: > At Sat, 9 Jun 2012 02:42:43 -0400, Vince Kuyatt wrote: >> While working on the Rhipmunk FFI, I ran into a definition called >> "NOT_GRABABLE_MASK", which as far as I can tell, is defined as: >> #define GRABABLE_MASK (1<<31) >> #define NOT_GRABABLE_MASK (~GRABABLE_MASK) >> >> The problem with this, is that when I do the same operations: >> (define GRABABLE_MASK (int->uint (arithmetic-shift 1 31))) >> (define NOT_GRABABLE_MASK (bitwise-not GRABABLE_MASK)) >> >> I get an error thrown back at me when I use it in one of the Chipmunk >> functions: >> Scheme->C: expects argument of type <uint32>; given -2147483649 >> >> How can I coerce the definitions of those two masks so that they will be a >> uint32 that I can pass to the Chipmunk API? > > I think you want > > (define (sint32->uint32 v) > (bitwise-and #xFFFFFFFF v)) > ____________________ Racket Users list: http://lists.racket-lang.org/users
