Re: [Powertop] [Warning fixes 5/6] Fix warning: warning: this decimal constant is unsigned only in ISO C90 [enabled by default] by explicitely declaring the value as UL

On Fri, Aug 24, 2012 at 11:54:33PM +0200, Joerg Mayer wrote:
> On Fri, Aug 24, 2012 at 08:18:58PM +0000, Howard, James D wrote:
> > A change was suggested in .../cpu.cpp at or near line 975, explicitly adding the "UL" suffix to the decimal integer literal:
> >      4294967295   -->   4294967295UL
> > Is that the right thing to do?  This is "ULONG_MAX" (for machines with 32-bit "word" size).  Would it be more correct to use the identifier ULONG_MAX?  In modern #include files, <limits.h> (for example) correctly provides the "UL" suffix.
> 
> If __WORDSIZE is 32 on all architectures that powertop will run on,
> then yes, we should use ULONG_MAX instead. I will have to find out about
> WORDSIZE on 64 bit architectures, as I'm still on a 32 bit system.
> 
> On sytems with __WORDSIZE of 64 bits ULONG_MAX is 18446744073709551615UL.
> 
> But that's something I will look at after a night's sleep.

OK, this was much less work than I thought:

On a 64 bit system that I have access to, /usr/include/bits/wordsize.h:

#if defined __x86_64__
# define __WORDSIZE     64
# define __WORDSIZE_COMPAT32    1
#else
# define __WORDSIZE     32
#endif

So I think the answer to your question should be "no", we should not use
ULONG_MAX.

Ciao
      Jaörg
-- 
Joerg Mayer                                           <jmayer(a)loplof.de>
We are stuck with technology when what we really want is just stuff that
works. Some say that should read Microsoft instead of technology.