[Pyrex] code specialisation/optimisation

[Robin Becker]

I notice in my C code base many complex routines which attempt to do
optimal loop unrolling etc etc. Typically they are pre-processor
specialised according to one or more flags.

A typical example is the use of byte switching when the endianness
matches the requirement.

What does pyrex allow/encourage in the way of this common C practice.
-- 
Robin Becker