From: "Frédéric Praca" <frederic.praca@free.fr>
Subject: Re: Representation clauses and side-efects on STM32F411 ravenscar runtime
Date: 02 Aug 2015 20:27:51 GMT
Date: 2015-08-02T22:27:51+02:00 [thread overview]
Message-ID: <55be7d47$0$3323$426a34cc@news.free.fr> (raw)
In-Reply-To: 87egjlla7z.fsf@theworld.com
Le Sun, 02 Aug 2015 16:13:52 -0400, Bob Duff a écrit :
> Frédéric Praca <frederic.praca@free.fr> writes:
>
>> 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.
>
> Then would a fixed-point type work?
>
> type Baud_Rate is delta 1.0/16 range ...;
> for Baud_Rate'Small use 1.0/16;
Maybe. I have to try this but this is tightly coupled to my example and
don't explain the side effects I also have on other records with
representation clauses :)
Anyway, it could be a better way to represent things I need to
investigate.
> - Bob
Fred
next prev parent reply other threads:[~2015-08-02 20:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-02 8:59 Representation clauses and side-efects on STM32F411 ravenscar runtime Frédéric Praca
2015-08-02 9:40 ` Simon Wright
2015-08-02 10:22 ` Simon Wright
2015-08-02 14:53 ` Frédéric Praca
2015-08-02 14:52 ` Frédéric Praca
2015-08-02 15:19 ` Simon Wright
2015-08-02 19:23 ` Jeffrey R. Carter
2015-08-02 19:54 ` Bob Duff
2015-08-02 20:01 ` Frédéric Praca
2015-08-02 20:13 ` Bob Duff
2015-08-02 20:27 ` Frédéric Praca [this message]
2015-08-02 20:31 ` Jeffrey R. Carter
2015-08-03 11:08 ` Simon Clubley
2015-08-15 14:22 ` Frédéric Praca
2015-08-15 15:33 ` Simon Clubley
2015-08-15 17:17 ` Frédéric Praca
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox