Am Friday 30 October 2015, 07:50:16 schrieb Sebastian Huber:
> How is this tackled in the glibc/Linux support? Is the exact layout of
> the structures really interesting for Ada? I guess its sufficient to
> tell Ada the size and alignment of pthread_attr_t for example.
>
In Linux they do it like this:
type pthread_attr_t is record
Data : char_array (1 .. OS_Constants.PTHREAD_ATTR_SIZE);
end record;
pragma Convention (C, pthread_attr_t);
for pthread_attr_t'Alignment use Interfaces.C.unsigned_long'Alignment;
That's probably the best solution. The gnat-rts changes values of the fields
only using the corresponding pthread_set functions.
If no one objects I would try to change the osinte-rtems.ads in the same manner.
> On 29/10/15 22:10, Jan Sommer wrote:
> > _NCPUWORDS is defined in newlib in newlib/libc/sys/rtems/sys/cpuset.h and
> > used to define the type cpu_set_t there.
> > typedef struct _cpuset {
> > cpu_set_word_t __bits[_NCPUWORDS];
> > } cpu_set_t;
> > cpu_set_t is used for a field in the struct pthread_attr_t in file
> > newlib/libc/include/types.h
> >
> > The Gnat Ada runtime uses POSIX-threads for tasking, therefore the
> > pthread-types have to be declared in Ada in order to import them.
> > As the fixed size array in cpu_set_t depends on the value of _NCPUWORDS it
> > is exported with the symbol _ada_ncpuwords in order to access it from
> > within the Ada runtime.
> >
> > The Ada declaration of pthread_attr_t is located in
> > gcc/ada/s-osinte-rtems.ads and _ada_ncpuwords is imported there.
> > ---
> > cpukit/libgnat/adasupp.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/cpukit/libgnat/adasupp.c b/cpukit/libgnat/adasupp.c
> > index 662b1cc..cde36b6 100644
> > --- a/cpukit/libgnat/adasupp.c
> > +++ b/cpukit/libgnat/adasupp.c
> > @@ -10,6 +10,10 @@
> > #include <rtems/posix/pthreadimpl.h>
> > #include <rtems/score/stackimpl.h>
> >
> > +
> > +/* export _NCPUWORDS for Ada */
> > +const size_t _ada_ncpuwords = _NCPUWORDS - 1;
> > +
> > /*
> > * _ada_pthread_minimum_stack_size
> > *
>
>
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