Re: Next priority: Maximum value of simulation time

John,

my usual nitpick:

The top-level const on the return-type is more or less ignored in C++.
So I would prefer to either return a plain value, or maybe even a
reference to a local static:

sc_time /* const & */
sc_max_time()
{
  static sc_time end_of_days =
     sc_time( double(~0ULL) / sc_get_time_resolution().to_seconds()
            , SC_SEC );
  return end_of_days;
}

Comments?

I don't think that there is the caveat of changing values with this
definition, though. The user can't change the time resolution, after
any sc_time objects have been created (5.10.3). And calling
sc_max_time() obviously creates one ... :-)

Greetings from Oldenburg,
 Philipp

On 13/09/10 17:18, john.aynsley@doulos.com wrote:

> Having discussed this internally, we've realized that a const does not
> work because the time resolution can be changed during elaboration. The
> following definition works, with the caveat that its value will change if
> the time resolution is changed. Its value cannot change during simulation.
>
> namespace sc_core {
>
> const sc_core::sc_time sc_max_time()
> {
> return
> sc_core::sc_time(double(~0ULL)/sc_core::sc_get_time_resolution().to_seconds(),
> sc_core::SC_SEC);
> }
>
> }
>
> John A
>
>
>
> From:
> David Long/doulos
> To:
> john.aynsley@doulos.com
> Cc:
> owner-systemc-p1666-technical@eda.org, systemc-p1666-technical@eda.org
> Date:
> 13/09/2010 15:23
> Subject:
> Re: Next priority: Maximum value of simulation time
>
>
>
> John,
>
> I was thinking of something along the lines of:
>
> Constant SC_MAX_TIME represents the maximum simulated time that may be
> reached.
>
> The definition could be implementation-defined. Alternatively it could be
> implemented by something like:
>
> const sc_time SC_MAX_TIME =
> sc_time(double(~0ULL)/sc_get_time_resolution().to_seconds(), SC_SEC);
>
> There is a constant UINT64_ZERO in sc_nbdefs.cpp that could be used in
> place of 0ULL but that is not mentioned in IEEE 1666-2005.
>
> Dave
>
>
>
> From:
> john.aynsley@doulos.com
> To:
> david.long@doulos.com, systemc-p1666-technical@eda.org
> Date:
> 13/09/2010 13:46
> Subject:
> Next priority: Maximum value of simulation time
> Sent by:
> owner-systemc-p1666-technical@eda.org
>
>
>
>
> Dave,
>
> You wrote:
>
> "5.10.1 states that time shall be represented internally by an unsigned
> integer of at least 64 bits. However, it does not provide any method to
> create an sc_time object that corresponds to the largest representable
> time (the sc_time constructor that takes a numeric value has double
> sc_time_unit arguments). One way to represent the maximum time would be to
> declare a "constant" sc_time object (e.g. SC_MAX_TIME) that took acount of
> the global time resolution that applies to the current simulation."
>
> Could you provide a spec and/or implementation for what you propose?
>
> Thanks,
>
> John A
>

-- 
Philipp A. Hartmann
Hardware/Software Design Methodology Group
OFFIS Institute for Information Technology
R&D Division Transportation · FuE-Bereich Verkehr
Escherweg 2 · 26121 Oldenburg · Germany
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