hi everyone,
i have written a couple of algorithms using the GCC builtin CAS, which
all works very nicely. it is a bit ugly and full of casts, and i am
trying to clean it up. i stumbled over something that i can't really
resolve however, and was wondering how other people do that:
// we are on 32bit, so this structure is 64 bits, just like a long long
struct gptr {
void *ptr;
int gen;
};
int main(int argc, char *argv[]) {
long long a, b;
long long *A = &a;
// works as expected
while (!__sync_bool_compare_and_swap(A, a, b)) {};
struct gptr c, d;
struct gptr *C = &c;
// incompatible type for argument 1 of `__sync_bool_compare_and_swap'
while (!__sync_bool_compare_and_swap(C, c, d)) {};
// works but is really ugly
while (!__sync_bool_compare_and_swap((long long*)C,
*(long long*)&c, *(long long*)&d)) {};
return 0;
}
as you can see i can use CAS on 8 byte primitives (long long int) quite
well, but if i use an equal sized struct instead i get an error. i can
of course cast it as shown above, but i was hoping that i just miss
something and that it can be done cleanly.
how are you guys doing that?
cu robert
--
Robert Lemmen http://www.semistable.com
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