[Python-Dev] ctypes is in SVN now.
theller at python.net
Fri Mar 10 22:01:28 CET 2006
Tim Peters wrote:
> [Thomas Heller]
>> And I never had tried it before on a sparc machine - all the intel and ppc processors
>> seem to have no problems with it.
> Pentiums don't enforce "natural" alignment restrictions, but run much
> slower on unaligned access (varying by specific chip model, and
> generally more heavily penalized as time goes on). In the good old
> days, Pentium was one of dozens of competing architectures, and was
> the oddball in catering to unaligned access. Now it's eternal
> "backward compatibility" with an early implementation accident. Most
> other architectures never catered to unaligned access, or did so only
> at the cost of generating an interrupt so that kernel-mode software
> could fake unaligned access. Bottom line is that unaligned access
> isn't portable and never was, and even on architectures where "it
> works" it can be extremely expensive to use it.
I was astonished to find out that also the ARM processor on Windows CE
doesn't support unaligned accesses. When one thinks about it, it probably
makes sense on small devices.
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