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Re: out-of-line and arch-specific random_device


On Tue, 28 Aug 2012, Ulrich Drepper wrote:

On Tue, Aug 28, 2012 at 3:47 AM, Marc Glisse <marc.glisse@inria.fr> wrote:
I assume they are different enough that they can't all be abstracted
behind a nice common builtin (with default implementation in libgcc
and/or a macro advertising fast implementations of it) :-(

What is different is the way to interact with the CPU facility to get the data. That's exactly the part I abstracted out in its own function. I named it __x86_rdrand() but that's more an historic accident. I should have named it __get_random_word. Then all that needs to be done for another architecture is to provide a definition of this function. The rest can be shared. But this function needs to be arch-specific since the details really differ sufficiently.

Thank you for your answers. My main concern was whether it was best to implement __get_random_word in libstdc++, or __builtin_random in gcc. But it looks like your solution of doing it in libstdc++ makes more sense (at least for now).


--
Marc Glisse


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