Re: [boost] How to structurate libraries ?

Subject: Re: [boost] How to structurate libraries ?
From: Joel Falcou (joel.falcou_at_[hidden])
Date: 2009-01-18 08:38:59

Mathias Gaunard a écrit :
> It is possible to do better than posix_memalign.
> When you use posix_memalign, you do not provide the alignment 
> information when freeing the memory. This does reduce the efficiency 
> of posix_memalign.
>
> In C++, however, you always know the alignment of the memory when you 
> free it.
>
I just checked this out indeed. Good to know for later.
>
> I'm fairly sure there is already a library that does just that.
>
Yes I just rediscovered it myself too.
> -> typed_bitfield that wraps a type T and a properly sized byte array 
> and provide proper byte access operator[]. Useful for decomposing 
> large types into bytes for low level operations.
>
> aligned_storage from type traits?
Hmmm, guess I have to watch this but I don't think it does what I think 
it does. I'll have a look.
Mind you that if it's already done, then that's less for me to maintain.
> How would it work without writing
> vec<float, 4> k = {5, 5, 5, 5};
> ?
>
> How can the minimum of a vector yield a vector?
> And isn't that already provided by Boost.uBlas?
>
Guess I typed this too early or too late in the evening/morning.

More details :
vec<T> encapsulates ONE sidm register, not a array.
So the type is enough to know, for a given platform, how many component 
fits in the SIMD type
(basically size of vector = 16/sizeof(T) for 128 bits wide SIMD 
extension, which is ofc handled correctly for less or greater extension).

Then again, there is a float missing before r as the min is indeed a scalar

As for uBlas, uBlas handle array of data and may use SIMD extension. 
This library provide a POD like type for SIMD values.

-- 
___________________________________________
Joel Falcou - Assistant Professor
PARALL Team - LRI - Universite Paris Sud XI
Tel : [phone]