Re: Representation clauses and side-efects on STM32F411 ravenscar runtime

["Frédéric Praca" <frederic.praca@free.fr>]

Le Sun, 02 Aug 2015 15:54:50 -0400, Bob Duff a écrit :

> "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> writes:
> 
>> On 08/02/2015 01:59 AM, Frédéric Praca wrote:
>>> 
>>>    type Mantissa is range 0 .. 2**12 - 1 with Size => 12;
>>>    type Fraction is range 0 .. 2**4 - 1 with Size => 4;
> 
> Note that the Sizes will be 12 and 4 by default.
> 
>> Wouldn't modular types be better for these?
> 
> Why would you want wraparound arithmetic for these?  Seems like it would
> just hide bugs.

I fully agree. Mantissa and Fraction don't have to use wraparound 
arithmetic. In fact, these two variables together represent a fixed point 
type and the magic must be inside the functions which calculates these 
variables according to the bus frequency and by the way must take care of 
the carry and possible overflow.

> - Bob