On Tue, 2010-08-17 at 19:16 -0400, Mathieu Desnoyers wrote: > +/* > + * Align pointer on natural object alignment. Object size must be power of > two. > + */
Hmm, I wonder if we should add a compiler bug here too. extern void __bug_obj_not_power_of_two(void); ({ if ((sizeof(*obj) - 1) & sizeof(*obj)) __bug_obj_not_power_of_two(); PTR_ALIGN((obj), __alignof__(*(obj))); }) > +#define object_align(obj) PTR_ALIGN((obj), __alignof__(*(obj))) > +#define object_align_floor(obj) PTR_ALIGN_FLOOR((obj), > __alignof__(*(obj))) > + > +/** > + * offset_align - Calculate the offset needed to align an object on its > natural > + * alignment towards higher addresses. > + * @align_drift: object offset from an "alignment"-aligned address. > + * @alignment: natural object alignment. Must be non-zero, power of 2. > + * > + * Returns the offset that must be added to align towards higher > + * addresses. > + */ > +static inline size_t offset_align(size_t align_drift, size_t alignment) > +{ > + return (alignment - align_drift) & (alignment - 1); > +} > + > +/** > + * offset_align_floor - Calculate the offset needed to align an object > + * on its natural alignment towards lower addresses. > + * @align_drift: object offset from an "alignment"-aligned address. > + * @alignment: natural object alignment. Must be non-zero, power of 2. > + * > + * Returns the offset that must be substracted to align towards lower > addresses. > + */ > +static inline size_t offset_align_floor(size_t align_drift, size_t alignment) > +{ > + return (align_drift - alignment) & (alignment - 1); > +} I take it that theses functions can have variables passed to it for alignment, thus a check wont help. Although, we could add a test for the constant case. -- Steve > + _______________________________________________ ltt-dev mailing list ltt-dev@lists.casi.polymtl.ca http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev