Messages in this thread | | | Date | Sun, 28 Mar 2010 18:40:29 +0300 | From | Imre Deak <> | Subject | Re: [RFC PATCH] create generic alignment api (v2) |
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On Sun, Mar 28, 2010 at 03:22:47AM +0200, ext Mathieu Desnoyers wrote: > [...] > +/** > + * 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); > +} > + > +#define object_align(object) \ > + ((typeof(object))((size_t) object + offset_align((size_t) object, \ > + sizeof(object)))) > + > +#define object_align_floor(object) \ > + ((typeof(object))((size_t) object - offset_align_floor((size_t) object,\ > + sizeof(object)))) > +
Here object must be a pointer, but then sizeof(object) will result in aligning to the arch word size not the object's natural alignment. Is this what you intended?
--Imre
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