[sane-devel] More Proposed Upgrades

[Olaf Meeuwissen]

Yury Tarasievich writes:

> On 09/29/2015 04:25 AM, m. allan noah wrote:
>> I just pushed all of these. I did re-write the microtek2 patch to use
>> the logic I pointed out in a prior mail.
>
> /meaning sequenced `% 2` changed to sequenced '!'/
>
> Isn't this fancy-coding now, though?
>
> I didn't look in the backend and may have 
> completely missed the point, however, applying 
> %2 to integers would (in gcc) change odd values 
> to 1s, even values to 0s, with subsequent 
> applications of the routine having no further 
> effect.
>
> Your change would interchange not-zeroes and 
> zeroes every time.

I *was* going to agree with you wholeheartedly until I looked the '!'
operator up at cppreference.com[1].

 [1] http://en.cppreference.com/w/c/language/operator_logical

That, combined with

  ms->buf.current_src = 0;         /* index to current buffer */

and

  uint8_t *src_buffer[2];     /* two buffers because of CCD gap */
  /*...*/
  int current_src;
 
and the use of ms->buf.current_src in backend/microtek2.c, made me
change my mind.

I agree with you that rewriting to use 0s and 1s is a clearer way of
preserving the intended meaning of the original expression, the spec
apparently says that !E evaluates to 1 for any scalar E that compares
equal to zero.  In that case, both ways are identical.

Hope this helps,
-- 
Olaf Meeuwissen, LPIC-2            FSF Associate Member since 2004-01-27
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