Using inline assembler

[anonymous via Digitalmars-d-learn]

On Thursday, 9 October 2014 at 13:29:27 UTC, Etienne wrote:
> On 2014-10-09 8:54 AM, anonymous wrote:
>> This compiles:
>>
>> align(16) union __m128i { ubyte[16] data; } /* note the 
>> position
>> of the semicolon */
>>
>> void store(__m128i* src, __m128i* dst) {
>>      asm
>>      {
>>          movdqu XMM0, [src]; /* note: [src] */
>>          movdqu [dst], XMM0;
>>      }
>> }
>
> Yes, this does compile, but the value from src never ends up 
> stored in dst.
>
> void main() {
> 	__m128i src;
> 	src.data[0] = 255;
> 	__m128i dst;
> 	writeln(src.data); // shows 255 at offset 0
> 	store(&src, &dst);
> 	writeln(dst.data); // remains set as the initial array
> }
>
> http://x86.renejeschke.de/html/file_module_x86_id_184.html
>
> Is this how it's meant to be used?

I'm out of my knowledge zone here, but it seems to work when you
move the pointers to registers first:

void store(__m128i* src, __m128i* dst) {
      asm
      {
          mov RAX, src;
          mov RBX, dst;
          movdqu XMM0, [RAX];
          movdqu [RBX], XMM0;
      }
}