[Python-Dev] ctypes is in SVN now. (original) (raw)

Thomas Heller 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.

Thomas

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