>>> Are there any current or contemplated NetBSD ports to
>>> non-2s-complement machines?
>> No, I don't think so.

At least not assuming you're talking about integer arithmetic; there
are many if you allow floating point.  (Most floating-point computer
arithmetics, including both IEEE and VAX, are sign-magnitude - I don't
think we have anything but the VAX that doesn't do IEEE float, do we?)

> ok ... I wondered because I wasn't sure why bit_ffs in bitstring(3)
> is done with a per-bit for loop, and thought maybe it meant 2s
> complement techniques would be making too much of an architecture
> assumption.

My opinion would be that they would not.  NetBSD already makes
architecture assumptions which are significantly more restrictive in
practice, like assuming that nil-pointer is all-bits-zero.

> Does anyone know of a reason not to use x^(x-1) in NetBSD code?

Not me, especially not since I think C's bitwise operations are defined
to operate as if the machine were two's-complement binary, whether it
actually is or not.  (Yes, this means C is a bad language for use on
machines that aren't 2's-c binary....)

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