Soft Floating Point Exceptions

[Brian Inglis]

On 2020-05-25 15:43, Brian Inglis wrote:
> On 2020-05-25 11:17, Joel Sherrill wrote:
>> An RTEMS GSoC student (Eshan Dhawan) has almost completed porting the
>> FreeBSD fenv code to newlib. Unfortunately, the software floating point
>> code calls  __softfloat_float_raise which has a couple of issues. First, he
>> can't find the code which probably indicates an issue in the BSD world but
>> no one likely cares because I doubt there is a BSD install on an ARM with
>> soft floating point.
>>
>> Second, to use this in newlib, we will be relying on GCC's soft float
>> implementation which means something different has to happen. Is there an
>> equivalent routine in GCC? What should happen for
>> __softfloat_float_raise()?
> 
> You will have to look at these to see what is relevant to your issue.
> 
> Interface:
> 
> $ info gccint libgcc soft
> 
> implementation:
> 
> https://gcc.gnu.org/git?p=gcc.git;a=blob_plain;f=libgcc/config/arm/sfp-machine.h;hb=HEAD
> https://gcc.gnu.org/git?p=gcc.git;a=blob_plain;f=libgcc/config/arm/ieee754-sf.S;hb=HEAD
> https://gcc.gnu.org/git?p=gcc.git;a=blob_plain;f=libgcc/config/arm/ieee754-df.S;hb=HEAD
> https://gcc.gnu.org/git?p=gcc.git;a=blob_plain;f=libgcc/config/arm/fp16.c;hb=HEAD
> 
> implementation:
> 
> https://github.com/freebsd/freebsd/commit/85aab3336e0d6172ddd5fe3cde38389abd612728
> https://github.com/freebsd/freebsd/tree/master/lib/libc/softfloat
> https://github.com/freebsd/freebsd/blob/master/lib/libc/softfloat/softfloat.txt#L357
> https://github.com/freebsd/freebsd/blob/master/lib/libc/softfloat/softfloat-for-gcc.h
> https://github.com/freebsd/freebsd/blob/master/lib/libc/softfloat/softfloat-specialize#L67
> 
> alternative:
> 
> http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/arch/arm/softfloat/
also
http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libm/softfloat/
http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc_fp/

and for latest updates:

http://www.jhauser.us/arithmetic/SoftFloat.html

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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