Re: [avr-libc-dev] bsearch() speed optimization. Opinions?

[E. Weddington]

Dmitry K. wrote:

> Hi all.
>
> Now bsearch function uses multiplication to everyone itteration. This
> operation can be excluded from a body of a cycle. I have tried to make
> it. In result speed of search considerably increase (for classic avr-s),
> but also the size of a code too has increased.
>
> Certainly, it is possible to include a new variant only for classic
> chips under condition of absence of a key `-Os', but I doubt, that such
> combination for anybody can be useful.
>
> Opinions?
>
> Comparison old and new 'bsearch' is below resulted:
>
> Search in 100-bytes array of chars (result was at first element).
>
> avr2            3.3.5   3.3.5   3.4.3   3.4.3   4.0     4.0
> ~~~~            -Os rr  -O3     -Os rr  -O3     -Os rr  -O3
>
> 1.2.0   size:   78+12   86+14   77+12   89+14   77+12   92+14
>        cls:    806     815     813     821     808     829
>
> 20050129 size:  93+14   93+14   83+12   106+14  89+12   106+14
>         cls:   670     551     533     546     554     545
>
>  
My only concern is that most users seem to complain about code *size* 
and not code *speed* especially as it concerns avr-libc functions. I 
wouldn't necessarily feel comfortable about having different versions 
that are built for different devices.

But, I also think that what you've been able to do is great! If there 
was any way to keep the size closer to the same it would be a win.

But, my objections are not strong either. If others think this would be 
better to put in, I wouldn't have problems with it.

Any other opinions?

Eric