Concise question:

I would like to use dynamic arrays, not for their
dynamic sizing properties per se' (slicing, appending, etc).
But, more for their memory protection and efficiencies (for
example,using foreach).

However, I must have the start of my array at an avx
friendly 32 byte alignment.

Is this easily acheivable?

Background:

I am interfacing with fftw. If I use the fftw_malloc, then
I am forced to either:

1. copy to/from the allocated arrays to/from my "standard"
   dlang dynamic arrays (loss of efficiency). or ...

2. use standard array/pointer mechanisms everywhere(loss
   of memory safely).

My thinking is that I could forego the use of the fftw_malloc,
and simply hand fftw functions my (properly aligned) pointer
of my dlang dynamic array.

All thoughts, comments, hints, greatly appreciated!

James

On Tuesday, 3 August 2021 at 12:33:56 UTC, james.p.leblanc wrote:

AFAIK, the GC only guarantees an alignment of 16. But you can turn any memory allocation into a slice, simply via

size_t length = ...;
T* myPtr = cast(T*) fftw_malloc(length * T.sizeof); // or aligned_alloc, posix_memalign etc.
T[] mySlice = myPtr[0 .. length];
foreach (ref e; mySlice) ...
// free!

On Tuesday, 3 August 2021 at 16:32:34 UTC, kinke wrote:

size_t length = ...;
T* myPtr = cast(T*) fftw_malloc(length * T.sizeof); // or aligned_alloc, posix_memalign etc.
T[] mySlice = myPtr[0 .. length];
foreach (ref e; mySlice) ...
// free!

Dear Kinke,

THANKS IMMENSELY!

This is exactly the kind of solution that I was hoping would
be possible (elegant, simply, and clear).

This really is the perfect solution, and opens up many possibilities for me.

(Perhaps I had been using the wrong search terms, or perhaps everyone already
knows how to use this "conversion of C arrays/pointers to D slices" solution...
but I was stumped!)

Again, thanks kindly

Is there some highly visible place this is already documented?
If not, it would make a great blog post as it would be beneficial
to any D newcomers bridging C/D and needing AVX alignments, etc.

Best Regards,
James