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Re: libm support for ARMv7 and VSQRT?
- From: Sebastian Huber <sebastian dot huber at embedded-brains dot de>
- To: "Richard Earnshaw (lists)" <Richard dot Earnshaw at arm dot com>, "newlib at sourceware dot org" <newlib at sourceware dot org>
- Date: Mon, 20 Mar 2017 15:54:35 +0100
- Subject: Re: libm support for ARMv7 and VSQRT?
- Authentication-results: sourceware.org; auth=none
- References: <58CF7C40.3060609@embedded-brains.de> <29ebecaa-287d-57e9-cffe-d1b5a05a6a7b@arm.com>
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
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