Re: Single precision math library, porting to eCos.

[Sergei Gavrikov <sergei.gavrikov@gmail.com>]

On Tue, 19 Jul 2011, Ilija Kocho wrote:

> Hello colleagues
 
Hello Ilija,

my $0.02.

> We are working on a port of Newlib's single precision math library
> /float/ type functions/. We are going to contribute the port, so we
> would like to know if there is interest to incorporate it into main
> eCos tree.

It's very excited and honour task. But, AFAIK, eCos libm are based on
Free Domain Libm fdlibm 5.X (5.2?). The *fdlibm* is a part of netlib
software collection, the references:

http://www.netlib.org/
http://www.netlib.org/fdlibm/

and it (fdlibm) is labeled as

C math library for machines that support IEEE 754 floating-point

> Rartionale: Some recent/upcoming architectures such as Cortex-M4,
> Cortex-R, MPC 55xx can execute single precision floating point in
> hardware. This is also recognised by GCC, for instance GCC 4.6 can
> generate /-mhard-float/ code for Cortex-M4.

Good point.

But, may be first you would look on *Cephes Mathematical Library*

http://www.netlib.org/cephes/singldoc.html

It would be nice to get a set of single precision special math functions
like logf(), sinf(), cosf(), etc. as eCos math alternative which cephes
provides us. But, this is my brief view only. It seemed for me that to
get *cephes* under eCos is less complex task than to port the same part
from NewLib (may be I wrong, I have not dived in the subject).

In any case I like your idea to use hardware for single precision
calculations and value your efforts in this direction.


Sergei

> Regards
> 
> Ilija Kocho, manager
> SIvA doo
> http://www.siva.mk
>