Messages in this thread | | | Date | Thu, 23 May 2019 19:51:10 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 5/7] lib: rework bitmap_parse() |
| |
On Thu, 9 May 2019 19:26:33 -0700 Yury Norov <yury.norov@gmail.com> wrote:
> Hi Andy, > > Thanks for thorough review. > > On Wed, May 08, 2019 at 11:46:32AM +0300, Andy Shevchenko wrote: > > On Tue, Apr 30, 2019 at 06:06:34PM -0700, Yury Norov wrote: > > > bitmap_parse() is ineffective and full of opaque variables and opencoded > > > parts. It leads to hard understanding and usage of it. This rework > > > includes: > > > - remove bitmap_shift_left() call from the cycle. Now it makes the > > > complexity of the algorithm as O(nbits^2). In the suggested approach > > > the input string is parsed in reverse direction, so no shifts needed; > > > - relax requirement on a single comma and no white spaces between chunks. > > > It is considered useful in scripting, and it aligns with > > > bitmap_parselist(); > > > - split bitmap_parse() to small readable helpers; > > > - make an explicit calculation of the end of input line at the > > > beginning, so users of the bitmap_parse() won't bother doing this. > > > > > +static inline bool in_str(const char *start, const char *ptr) > > > +{ > > > + return start <= ptr; > > > +} > > > + > > > > The explicit use of the conditional is better. > > > > -- > > With Best Regards, > > Andy Shevchenko > > I still think that is_str() is more verbose, but it's minor issue > anyways, so I obey. Below is the patch that removes the function. > It's up to Andrew finally, either apply it or not.
I agree with Andy - open-coding the comparisons makes it easier to understand the varoius in_str() callsites, IMO.
> @@ -653,7 +648,7 @@ int bitmap_parse(const char *start, unsigned int buflen, > u32 *bitmap = (u32 *)maskp; > int unset_bit; > > - while (in_str(start, (end = bitmap_find_region_reverse(start, end)))) { > + while (start <= (end = bitmap_find_region_reverse(start, end))) {
This statement hurts my little brain. Can it be broken into easier to digest chunks?
> if (!chunks--) > return -EOVERFLOW; >
| |