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Groups > comp.lang.c > #105935
| Newsgroups | comp.lang.c |
|---|---|
| Date | 2017-03-13 12:31 -0700 |
| References | (5 earlier) <3fb4148c-8b5b-468c-8399-e5a5fc8575ee@googlegroups.com> <2a17cclqhuuefeu73qfko4u75p59986s9j@4ax.com> <80c60d8c-ba95-43fa-b7fa-ce45f1935a14@googlegroups.com> <338862bf-1ebf-41f0-ac0a-1d9f0fe53b3d@googlegroups.com> <CIBxA.61777$Bp6.32071@fx36.iad> |
| Message-ID | <2ec6e145-0ae4-4e92-8a3b-cfefdc93cbdb@googlegroups.com> (permalink) |
| Subject | Re: va_start without the first argument? |
| From | Thiago Adams <thiago.adams@gmail.com> |
On Monday, March 13, 2017 at 3:40:41 PM UTC-3, Scott Lurndal wrote:
> Thiago Adams writes:
> >On Monday, March 13, 2017 at 2:30:07 PM UTC-3, Thiago Adams wrote:
> >[...]
> >> > >> >I opened the definition of va_list etc from Visual C++ 2017 includes:
> >> > >> >
> >> > >> >typedef char* va_list;
> >> > >> >
> >> > >> >
> >> > >> >#define _ADDRESSOF(v) (&(v))
> >> > >> >
> >> > >> >#define _INTSIZEOF(n) ((sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1))
> >> > >> >
> >> > >> >#define __crt_va_start_a(ap, v) ((void)(ap = (va_list)_ADDRESSOF(v) + _INTSIZEOF(v)))
> >> > >> >
> >> > >> >#define __crt_va_arg(ap, t) (*(t*)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)))
> >> > >> >
> >> > >> >
> >> > >> >#define __crt_va_end(ap) ((void)(ap = (va_list)0))
> >> > >> >
> >> > >> >The macro _INTSIZEOF has some tricks I don't understand.
> >
> >
> >
> >If someone is interested.. For x64
> >
> >
> >#elif defined _M_X64
> >
> > void __cdecl __va_start(va_list* , ...);
> >
> > #define __crt_va_start_a(ap, x) ((void)(__va_start(&ap, x)))
> > #define __crt_va_arg(ap, t) \
> > ((sizeof(t) > sizeof(__int64) || (sizeof(t) & (sizeof(t) - 1)) != 0) \
> > ? **(t**)((ap += sizeof(__int64)) - sizeof(__int64)) \
> > : *(t* )((ap += sizeof(__int64)) - sizeof(__int64)))
> > #define __crt_va_end(ap) ((void)(ap = (va_list)0))
> >
> >#endif
> >
> >__va_start is not macro.
> >
> >
>
> You find varargs documented in the processor-specific ABI. For example,
> see: http://refspecs.linuxfoundation.org/elf/x86_64-abi-0.98.pdf (section 3.5.7).
>
> The va_list Type
> The va_list type is an array containing a single element of one structure con-
> taining the necessary information to implement the va_arg macro. The C defi-
> nition of va_list type is given in figure 3.34.
>
> Figure 3.34: va_list Type Declaration
> typedef struct {
> unsigned int gp_offset;
> unsigned int fp_offset;
> void *overflow_arg_area;
> void *reg_save_area;
> } va_list[1];
>
> ...
Thanks for the link.
I was trying to use the va_list memory layout just to
use one exiting concept.
The same function created for it could be used in other context.
No need to learn more concepts.
But, if the price for this is too high, I could use another
memory layout.
For instance, put everything in char*.
Is char* too bad?
void *p = malloc(sizeof(int) + sizeof(double));
*((*int)p) = 1;
p += sizeof(int);
*((*double)p) = 2.0;
p += sizeof(double);
If not I can just create a new version of macros va_arg, va_start.
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va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 11:57 -0800
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 12:04 -0800
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-10 12:32 -0800
Re: va_start without the first argument? "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-03-10 15:51 -0500
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 14:36 -0800
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 14:53 -0800
Re: va_start without the first argument? Robert Wessel <robertwessel2@yahoo.com> - 2017-03-10 17:14 -0600
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 15:37 -0800
Re: va_start without the first argument? Robert Wessel <robertwessel2@yahoo.com> - 2017-03-10 23:12 -0600
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 10:29 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 11:31 -0700
Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-13 18:40 +0000
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 12:31 -0700
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-11 19:53 +0100
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-11 19:05 +0000
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-11 11:56 -0800
Re: va_start without the first argument? antispam@math.uni.wroc.pl - 2017-03-12 05:41 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 13:52 +0100
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-12 14:40 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 18:13 +0100
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-12 18:04 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 21:04 +0100
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-12 21:02 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 22:40 +0100
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-12 15:51 -0700
Re: va_start without the first argument? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-03-12 16:52 -0700
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-13 00:56 +0100
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-13 09:17 -0700
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 17:54 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-13 22:12 +0100
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 22:48 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 13:46 +0100
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-14 13:37 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 15:24 +0100
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 08:25 -0700
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 17:02 +0100
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 09:45 -0700
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 09:15 -0700
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 10:02 -0700
Re: va_start without the first argument? jt@toerring.de (Jens Thoms Toerring) - 2017-03-14 20:32 +0000
Re: va_start without the first argument? raltbos@xs4all.nl (Richard Bos) - 2017-03-14 07:44 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 13:38 +0100
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 08:57 -0700
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-13 11:21 -0700
Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-13 18:33 +0000
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-13 22:08 +0100
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-13 15:23 -0700
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 13:58 +0100
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 09:18 -0700
Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 16:52 +0000
Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 11:34 -0700
Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 18:54 +0000
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 13:30 -0700
Re: va_start without the first argument? Ike Naar <ike@iceland.freeshell.org> - 2017-03-15 21:55 +0000
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-15 15:16 -0700
Re: va_start without the first argument? Philip Lantz <prl@canterey.us> - 2017-03-23 21:04 -0700
Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 21:48 +0100
Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 14:01 +0000
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 07:42 -0700
Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 12:38 +0000
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-13 01:11 +0100
Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-13 15:43 +1300
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 10:36 +0000
Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-14 07:33 +1300
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 19:00 +0000
Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-14 08:05 +1300
Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 23:10 +0000
Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-14 17:38 +1300
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-14 05:48 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 12:12 -0700
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-12 19:39 +0100
Re: va_start without the first argument? jt@toerring.de (Jens Thoms Toerring) - 2017-03-10 20:49 +0000
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 14:41 -0800
Re: va_start without the first argument? John Bode <jfbode1029@gmail.com> - 2017-03-10 16:05 -0800
Re: va_start without the first argument? jacob navia <jacob@jacob.remcomp.fr> - 2017-03-11 21:47 +0100
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-11 13:07 -0800
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-11 22:24 +0100
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 05:44 -0700
Re: va_start without the first argument? Jerry Stuckle <jstucklex@attglobal.net> - 2017-03-13 08:59 -0400
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 06:17 -0700
Re: va_start without the first argument? Jerry Stuckle <jstucklex@attglobal.net> - 2017-03-13 13:27 -0400
Re: va_start without the first argument? Jerry Stuckle <jstucklex@attglobal.net> - 2017-03-13 13:30 -0400
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 11:00 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 10:34 -0700
Re: va_start without the first argument? antispam@math.uni.wroc.pl - 2017-03-12 06:00 +0000
Re: va_start without the first argument? gordonb.gas5o@burditt.org (Gordon Burditt) - 2017-03-17 09:46 -0500
Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-17 09:07 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 05:39 -0700
Re: va_start without the first argument? John Bode <jfbode1029@gmail.com> - 2017-03-13 11:40 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 12:01 -0700
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-13 23:17 +0100
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 16:15 -0700
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-14 00:26 +0100
Re: va_start without the first argument? kikiins@gmail.com - 2017-03-13 16:51 -0700
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-14 01:12 +0100
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 18:24 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 18:57 -0700
Re: va_start without the first argument? raltbos@xs4all.nl (Richard Bos) - 2017-03-14 07:59 +0000
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-14 06:45 -0700
Re: va_start without the first argument? Robert Wessel <robertwessel2@yahoo.com> - 2017-03-13 18:20 -0500
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-14 00:31 +0100
Re: va_start without the first argument? raltbos@xs4all.nl (Richard Bos) - 2017-03-13 16:51 +0000
Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-11 19:29 +0100
Re: va_start without the first argument? Siri Cruise <chine.bleu@yahoo.com> - 2017-03-11 12:12 -0800
Re: va_start without the first argument? luser droog <luser.droog@gmail.com> - 2017-03-13 05:37 -0700
Re: va_start without the first argument? luser droog <luser.droog@gmail.com> - 2017-03-15 11:45 -0700
Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-15 13:39 -0700
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