[ECOS] Re: vfnprintf and floating point.

Bart Veer bartv@cygnus.co.uk
Wed Oct 6 07:27:00 GMT 1999


>>>>> "Sergei" == Sergei Organov <osv@Javad.RU> writes:

    Sergei> I'm aware of this statement in C standard. That's why I
    Sergei> tried to pass 'va_list*', not 'va_list' to the cvt().
    Sergei> Unfortunately in PowerPC va_list declared like 'typedef
    Sergei> _tag struct {...} va_list[1];'. This causes troubles.
    Sergei> Consider:

    Sergei> typedef int Type[1];

    Sergei> void boo(Type* ptype);

    Sergei> void foo(Type t)
    Sergei> {
    Sergei>   boo(&t); // Trouble here: &t has type 'T**', and 'boo' needs
    Sergei>            // type  'int (*)[1]'.
    Sergei> }

    Sergei> Just now I don't see how to avoid this.

OK, I have done some more checking. The 1989 standard does not go into
further detail on this, so it is debatable whether or not passing a
va_list via a pointer rather than by value is legal. According to a
draft of the C9x standard it is legal to pass a pointer to a va_list
to another function things should work as you expect. The C++ standard
does not address the issue directly, it just references the C
standard. This is one of the areas that will have to be addressed as
gcc moves to C9x compliance, but it may take a while before anything
happens.

Bart Veer // eCos net maintainer


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