Translating inline ASM from C++

[Etienne via Digitalmars-d-learn]

I'm translating some library from C++ and I'd need some help with 
assembler translations. I've read the guides on D inline assembler but 
it's fairly thin. I don't understand what "=r", "=a", "%0", "%1" should 
be in D. Is this some sort of register?

https://github.com/etcimon/botan/blob/master/source/botan/entropy/hres_timer.d#L107

I currently only need to translate these commented statements. If anyone 
could donate some code for it I'd be grateful, and it would help us all 
move towards a completely native crypto/ssl library ;)