Re: SC_IS_PRERELEASE and TLM_IS_PRERELEASE

The standard definitely says lowercase true/false are the correct values. However,
there is another consideration, CPP, the C preprocessor. The GNU 4.0 manual states:

> The preprocessor does not know anything about types in the language. Therefore, sizeof operators are not recognized in ‘#if’, and neither are enum constants. They will be taken as identifiers which are not macros, and replaced by zero. In the case of sizeof, this is likely to cause the expression to be invalid.
>
> The preprocessor calculates the value of expression. It carries out all calculations in the widest integer type known to the compiler; on most machines supported by GCC this is 64 bits. This is not the same rule as the compiler uses to calculate the value of a constant expression, and may give different results in some cases. If the value comes out to be nonzero, the ‘#if’ succeeds and the controlled text is included; otherwise it is skipped.

So I think we should use 1 and 0.

On Jan 17, 2011, at 5:31 PM, Philipp A. Hartmann wrote:

> John,
>
> I've checked this issue on MS Visual C++ as well. There, TRUE/FALSE are
> defined (due to windows.h) and unfortunaly true/false are not supported
> as constant expression (although they should, according to my
> understanding of the C++ standard).
>
> A platform independent definition should then use 1/0, respectively.
> Thus, the extended wording from my last mail seems to be the best way to
> go. The implementer can then provide a suitable definition for all the
> supported platforms.
>
> Opinions?
>
> Greetings from Oldenburg,
> Philipp
>
> On 12/01/11 15:42, Philipp A. Hartmann wrote:
>> John,
>>
>> On 12/01/11 15:13, john.aynsley@doulos.com wrote:
>>>
>>> What precisely are you proposing we do instead?
>>
>> For simplicity, I would propose to just spell 'false' and 'true' in
>> lower-case. These are valid constant expressions for the C(++)
>> preprocessor, evaluating to 0 and 1.
>>
>> A more elaborate definition could use the following:
>>
>> The TLM_IS_PRERELEASE flag shall be a controlling constant expression
>> (see ISO/IEC14882:2003, 16.1(4)), evaluating to 0 or 1, respectively.
>>
>> Greetings from Oldenburg,
>> Philipp
>>
>>
>>
>>> From:
>>> "Philipp A. Hartmann" <philipp.hartmann@offis.de>
>>> To:
>>> john.aynsley@doulos.com
>>> Cc:
>>> systemc-p1666-technical@eda.org
>>> Date:
>>> 12/01/2011 01:45
>>> Subject:
>>> Re: SC_IS_PRERELEASE and TLM_IS_PRERELEASE
>>>
>>>
>>>
>>> John, all,
>>>
>>> I've checked this again. TRUE and FALSE are neither part of the C nor
>>> the C++ standard.
>>>
>>> They are defined by some platforms (e.g. on Windows), and also
>>> commonly defined in C applications, but the latter mostly due to the
>>> lack of proper bool support.
>>>
>>> Wrt. to backwards compatibility, I highly doubt that there are
>>> frequent uses of this, since the current TLM-2 kit is just broken in
>>> that regard. Try the following on a non-Windows platform:
>>>
>>> // ---8<---
>>> #include <systemc>
>>> #include <tlm.h>
>>>
>>> int sc_main( int, char*[] )
>>> {
>>> # if TLM_IS_PRERELEASE == TRUE
>>> std::cout << "TLM pre-release" << std::endl;
>>> # endif
>>>
>>> # if TLM_IS_PRERELEASE == FALSE
>>> std::cout << "TLM not a pre-release" << std::endl;
>>> # endif
>>> return 0;
>>> }
>>> // --->8---
>>>
>>> This prints, _both_ lines on my default Linux/GCC 4.4 platform, since
>>> TRUE and FALSE are undefined. And comparing two undefined symbols is
>>> quite ? undefined. ;-)
>>>
>>> Greetings from Oldenburg,
>>> Philipp
>>>
>>> On 11/01/11 13:37, john.aynsley@doulos.com wrote:
>>>> All,
>>>>
>>>> Philipp writes:
>>>>
>>>>
>>>> 9.6.5 SystemC Version
>>>> 11.8.1 TLM version information
>>>>
>>>> SC_IS_PRERELEASE
>>>> TLM_IS_PRERELEASE
>>>>
>>>> "... flag shall be either FALSE or TRUE, not enclosed in quotation
>>>> marks."
>>>>
>>>> Hmmm, maybe 'true' or 'false' (lower-case) would be more portable?
>>>> Or even an application-defined integral constant expression evaluating
>>>
>>>> to 0/1 (or false/true).
>>>>
>>>>
>>>> [JA] I guess FALSE and TRUE are still required for backward
>>> compatibility
>>>> in the TLM-2.0 world?
>
>
> --
> 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 · http://offis.de/en/
> Phone/Fax: +49-441-9722-420/282 · PGP: 0x9161A5C0 · Skype: phi.har
>
>
> --
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>

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