On Tue, Mar 26, 2019 at 07:08:18PM +0900, William Breathitt Gray wrote: > On Tue, Mar 26, 2019 at 10:43:45AM +0100, Lukas Wunner wrote: > > I'd try to avoid copying around the clump value and use a pointer > > to u8 instead. > > Although in this case we are handling 8-bit clumps, I anticipate device > drivers in the future which may benefit from larger size clumps (e.g. > GPIO devices with 24-bit ports). It'll be better to define clumps > similar to how we're defining bitmaps now (unsigned long *) so that we > can support these sizes if need be in the future without requiring data > type changes. It's just that copying around data in memory may be more expensive than, say, returning from a function, in which case it's usually stored in a register. > In this case, bitmap_get_value8 could be simplified to something like > this: > > index = BIT_WORD(start); > offset = start % BITS_PER_LONG; > return (bitmap[index] >> offset) & 0xFF; Hm, shouldn't that be "offset = round_down(start, 8)" ? (I prefer the multi-line version FWIW.) > Would it be better to define bitmap_get_value8 as a macro then? Or a static inline. Thanks, Lukas
