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Re: C99 support in Newlib

On 1/14/2016 8:04 AM, Andre Vieira (lists) wrote:
On 11/01/16 14:27, Andre Vieira (lists) wrote:
On 20/01/15 11:49, Freddie Chopin wrote:
On 01/20/2015 12:46 PM, Corinna Vinschen wrote:
On Jan 20 12:21, Freddie Chopin wrote:
On 01/20/2015 11:06 AM, Corinna Vinschen wrote:
On Jan 20 17:19, Joey Ye wrote:
Corinna, May I know which features are missing please?
As far as I can tell, mainly the long double functions for targets
with sizeof(double) != sizeof(long double).
I have one more - from my recent browsing of scanf() code, I assume
"%[...]" is supported, but "%[^...]" is not.
No, it is.  See libc/stdio/sccl.c.

Right, my mistake (; Sorry for the noise then (;


Hi there,

I thought I'd reply to this thread as it is very much related to my issue.

In a recent GCC patch a change to an optimization, which now checks for
the existence of libc support for C99 functions, lead to a regression
for arm-none-eabi. This is because currently GCC is set up to assume no
C99 support is available for arm-none-eabi. As far as I know this is
because it comes with newlib and as this thread points out it does not
claim to fully support C99. See

Hopefully with some help I can figure out what GCC 'function classes'
can be seen as supported by newlib for arm-none-eabi. These function
classes are:

     functions only part of the standard in C94 or above.
     functions only part of the standard in C99 or above.
     math complex functions only part of the standard in C99 or above.
     functions only part of the standard in C11 or above

And there is also 'function_sincos' for which I couldn't find a
definition though I assume its for the GNU extension 'sincos'.

$arm-none-eabi-nm libm.a | grep sincos
00000000 T sincos
00000000 T sincosf

Can someone confirm the support or lack thereof for these classes in
newlib for 'arm-none-eabi'.



As an investigation exercise I constructed a list of all functions in
the C99 standard and I checked whether the newlib version we build for
arm-none-eabi defined these and I found that it was missing quite a lot
of them! See attached file.

That answers my question for the bugzilla ticket. We can not enable
function_c99_* function class support for arm-none-eabi.

I think you checked it against C11. I spotted thrd_create on the list
and don't think that is C99.

My quick impression is:

+  to agree that the math methods are C99 and missing.
+ thread, mutex and other concurrency objects are C11
+ *_s is C11
+ timespec_get is C11

At least that's based on Did I miss something?

I agree a complete set of C99 methods is important.

C11 adds some things which newlib should support and others which
are the domain of the hosting environment. Newlib doesn't support
pthreads for example (but has pthread.h) so C11 threads should
follow the same pattern.


Joel Sherrill, Ph.D.             Director of Research & Development        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985

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