C++ Logo

STD-PROPOSALS

Advanced search

Subject: Re: [std-proposals] Restrict possible values of CHAR_BIT
From: Tom Honermann (tom_at_[hidden])
Date: 2019-10-24 12:32:47


What is the motivation?  What problem(s) would this solve?

Tom.

On 10/24/19 1:30 PM, Lyberta via Std-Proposals wrote:
> I propose to restrict possible values of CHAR_BIT to be 8 * (2 ^ n)
> where n is a non-negative integer.
>
> This gives values of 8, 16, 32, 64, 128 and so on.
>
> I have surveyed the most likely hardware architectures that would not
> fit with this restriction - computers with 24 bit bytes i.e. where
> CHAR_BIT == 24.
>
> The most extensive information I could find is on Wikipedia:
>
> https://en.wikipedia.org/wiki/24-bit
> https://en.wikipedia.org/wiki/Category:24-bit_computers
>
> It seems like the only candidate that is still relevant is Motorola
> 56000 series:
>
> https://en.wikipedia.org/wiki/Motorola_56000
>
> However, the specification says that it uses 8 bit bytes:
>
> http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf
>
> Therefore, I couldn't find implementations where CHAR_BIT == 24 which
> means other more exotic cases probably never existed.
>
>



STD-PROPOSALS list run by std-proposals-owner@lists.isocpp.org

Standard Proposals Archives on Google Groups