Re: Thou shalt have no other gods before the ANSI C standard

From: CBFalconer (cbfalconer_at_yahoo.com)
Date: 02/14/05 

Date: Mon, 14 Feb 2005 15:10:24 GMT

"John E. Hadstate" wrote:
> "CBFalconer" <cbfalconer@yahoo.com> wrote in message
>
... snip ...
>
>> Think trap values.
>> For example, all we have to do is give up one negative value,
>> and we can dynamically detect use of uninitialized variables.
>
> Yes, but which one shall we designate for that purpose?
> 0x80000000? Nope, I like that for a lot of things.
> 0xFFFFFFFF? I don't think so. 0xCCCCCCCC? Well, that's nice
> until my random number generator counts to that state.

Has to be 0x80...0. A continuous set of negative integers from -1
down is required. Assuming 2's complement, else the optimum choice
would be 0..0 for 1's complement, with all 1s representing 0 and
arithmetic done with a subtractor.

>
>> Another high reliability configuration on a 32 bit physical word
>> would be a 26 bit integer, with a trap uninitialized value, and 6
>> bits ecc syndrome. I think that works. Note that, with an 8 bit
>> byte, sizeof(int) would still be 4.
>
> For such a monstrosity, I would expect the C compiler to
> generate code for 26-bit arithmetic and use a 13-bit char.
> I would expect sizeof(int) to be 2.

Won't work, because of the requirement to expose all bits via
unsigned chars. This also makes ints a suitable and reliable
repository for Unicode chars.

Please fix (or replace) your alleged newsreader so that it doesn't
rewrap everything it misquotes. It is a pain to have to go through
the quotations and fix the harm. 

-- 
"If you want to post a followup via groups.google.com, don't use
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