Re: Using memcpy or memmove instead of for loop in liboctave/array/dim-vector.h

[John W. Eaton]

On 11/09/2013 05:28 AM, c. wrote:
> On 9 Nov 2013, at 04:57, PrasannaKumar Muralidharan<address@hidden>  wrote:
>
> > Hi Octave maintainers,
> >
> > In liboctave/array/dim-vector.h clonerep and resizerep functions are
> > defined. They use for loop for copying data. Is it possible to use
> > memcpy or memmove instead? The mem* function may be faster than for
> > loop as its implementation can use SIMD instructions when possible.
> >
> > Will it be useful or does it make sense?
> >
> > Thanks and Regards,
> > PrasannaKumar
>
> I doubt this would make a huge difference in performance for any application
>   as dim_vector objects have the size of the number of dimensions in an array,
> which is usually a small number.

Yes, nearly always just 2 or 3 dimensions plus the reference count and 
number of dimensions (they are all stored together in the same array). 
So I doubt that changing the way this copy is done will make much 
difference.

> I personally think it would look cleaner to use C++ style functions like
> std::copy and std::move rather than the C equivalents, though.
>
> I don't see an rule about this in the coding standard, is there a preference
> for using either C or C++ standard library functions?

Yes, C++ library functions are usually preferred over calling C library 
functions directly.

jwe