primitive vector types

[Andrei Alexandrescu]

Denis Koroskin wrote:
> On Thu, 19 Feb 2009 22:25:04 +0300, Mattias Holm 
> <hannibal.holm at gmail.com> wrote:
> 
>> Since (SIMD) vectors are so common and every reasonabe system support 
>> them in one way or the other (and scalar emulation of this is rather 
>> simple), why not have support for this in D directly?
>>
>> Yes, the array operations are nice (and one of the main reasons for 
>> why I like D :) ), but have the problem that an array of floats must 
>> be aligned on float boundaries and not vector boundaries. In my mind 
>> vectors are a primitive data type that should be exposed by the 
>> programming language.
>>
>> Something OpenCL-like:
>>
>>     float4 vec;
>>     vec.xyzw = {1.0,1.0, 1.0, 1.0}; // assignment
>>     vec.xyzw = vec.wyxz; // permutation
>>     vec[i] = 1.0; // indexing
>>
>> And then we can easily immagine some extra nice features to have with 
>> respect to operators:
>>
>>     vec ^ vec2; // 3d cross product for float vectors, for int vectors 
>> xor
>>
>> Has this been discussed before?
>>
>> / Mattias
>>
> 
> I don't see any reason why float4 can't be made a library type.

Yah, I was thinking the same:

struct float4
{
     __align(16) float[4] data; // right syntax and value?
     alias data this;
}

This looks like something that should go into std.matrix pronto. It even 
has value semantics even though fixed arrays don't :o/.


Andrei