[speex-dev] SIMD interest

[Jean-Marc Valin]

> On Intel, there is a instruction you can use to find out what version of
> the CPU you have and by extension what level of vector support it
> provides. One problem is that this instruction isn't on every processor
> you are likely to run across, so you still have to do the try/catch method
> to determine if that instruction is available. Intel has written some code
> that does this into libpr0n, which is the native image library for
> Mozilla. You can take a peak at that if you like. They also discuss it in
> their software optimization manuals.

Well, cpu detection is one thing (the instruction is "cpuid"), but the
main problem is detecting that the OS supports the xmm resgisters.
That's where it was simpler to just try something and catch the illegal
instruction. Maybe there's a special register in the CPU where that the
OS sets when it supports SSE, but I haven't found it.

        Jean-Marc


-- 
Jean-Marc Valin, M.Sc.A., ing. jr.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada


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