Re: [PATCH v5 2/2] mtd: rawnand: use bit-wise majority to recover the contents of ONFI parameter

From: Andy Shevchenko
Date: Tue May 15 2018 - 03:46:08 EST


On Tue, May 15, 2018 at 10:35 AM, Boris Brezillon
<boris.brezillon@xxxxxxxxxxx> wrote:
> On Mon, 14 May 2018 20:54:36 +0300
> Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
>
>> On Thu, May 10, 2018 at 3:03 PM, Boris Brezillon
>> <boris.brezillon@xxxxxxxxxxx> wrote:
>>
>> >> +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01)
>> >
>> > Not sure we need that macro, see below.
>>
>> +1. We have too many nice helpers for bit manipulations
>> (for_each_set_bit() as an example).
>>
>>
>> > for (k = 0; k < nbufs; k++) {
>> > const u8 *srcbuf = srcbufs[j];
>> >
>> > if (srcbuf[i] & BIT(k))
>> > m++;
>> > }
>>
>> ...which is effectively hweightXX().
>
> No it's not.

I don't see how "not". In the loop everithing except m and k are
invariants. What did I miss?

The powerness of two of nbufs is another thing of _existing_
prototypes of hweightXX().

--
With Best Regards,
Andy Shevchenko