libm support for ARMv7 and VSQRT?

[Sebastian Huber]

On 20/03/17 14:31, Richard Earnshaw (lists) wrote:
> On 20/03/17 06:52, Sebastian Huber wrote:
>> Hello,
>>
>> there is some ARM-specific libm support for ARMv8:
>>
>> https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=tree;f=newlib/libm/machine/arm;h=5457f11619b2d67e8f56f352afb404c06a12c2bb;hb=HEAD
>>
>>
>> The VFPv2+ supports a VSQRT instruction. Would it make sense to use it
>> for the sqrt() implementation, similar to
>>
>> https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libm/machine/aarch64/e_sqrt.c;h=e4b7554ac1811bf04f726da198b913c0c30595ca;hb=HEAD
>>
>> https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libm/machine/aarch64/ef_sqrt.c;h=19fec952517769ad3851efef3b11dc6c02fb7582;hb=HEAD
>>
>>
>> ?
>>
> I'm sure a patch would be welcome :-)

The ARMv7-AR reference manual is quite verbose if it comes to the 
floating-point square root implementation of VSQRT. Is it IEEE 754 
compatible?

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.