Re: missing methods in inttypes.h

[Corinna Vinschen <vinschen at redhat dot com>]

On Jul 30 09:00, Joel Sherrill wrote:
> On 7/30/2013 4:13 AM, Corinna Vinschen wrote:
> >On Jul 29 09:14, Joel Sherrill wrote:
> >>Hi
> >>
> >>I am curious where the missing methods from inttypes.h
> >>should go (eventually) in the source tree?
> >>
> >>intmax_t  imaxabs(intmax_t);
> >>imaxdiv_t imaxdiv(intmax_t, intmax_t);
> >>intmax_t  strtoimax(const char *restrict, char **restrict, int);
> >>uintmax_t strtoumax(const char *restrict, char **restrict, int);
> >>intmax_t  wcstoimax(const wchar_t *restrict, wchar_t **restrict, int);
> >>uintmax_t wcstoumax(const wchar_t *restrict, wchar_t **restrict, int);
> >For Cygwin, they are just aliases of the respective method using the
> >biggest available datatype:
> >
> >   imaxabs = llabs
> >   imaxdiv = lldiv
> >   strtoimax = strtoll
> >   strtoumax = strtoull
> >   wcstoimax = wcstoll
> >   wcstoumax = wcstoull
> >
> >In theory, every target can handle it that way without the need
> >to implement these functions explicitely.
> When you say aliases, do you mean just wrapper methods?
> 
> Can the Cygwin versions be merged into newlib so every newlib target
> has these?

The current Cygwin method can't be folded into newlib because it
uses ld's DEF file facility which is Windows-specific.

However, what we could do in newlib is either adding #defines as in

  #define strtoimax strtoll

etc., or we could use symbol aliases as in

  #define EXPORT_ALIAS(sym,symalias) extern "C" __typeof (sym) symalias __attribute__ ((alias(#sym)));

  strtoll ()
  {
  }
  
  EXPORT_ALIAS (strtoll, strtoimax)

We use this in Cygwin as well in some cases.

> FWIW when I looked at FreeBSD, the few I looked at had their own
> real implementations which were not wrappers. I can see that wrapping
> the largest type is OK though.

It's also better for small targets if there's only one implementation,
I think.


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat