Fixed-Point Arithmetic Project

[Chao-ying Fu]

Hello,



  The supported fixed data types are "fixed" in the Embedded-C spec.

Depending on targets, the numbers of integer/fractional

data bits cannot be changed after configuration.  Also, there are no

decimal fixed-point types.

Ex:

1. HQ is a signed 16-bit fractional data type, and the MIPS backend

will configure 15-bit fractional bits and no integer bits.

2. SQ is a signed 32-bit fractional data type, and the MIPS backend

will configure 31-bit fractional bits and no integer bits.



  I am not sure if this meets the need for ADA.  Thanks!


Regards,

Chao-ying

----- Original Message ----- 
From: "Duncan Sands" <duncan.sands@math.u-psud.fr>
To: "Robert Dewar" <dewar@adacore.com>
Cc: <gcc@gcc.gnu.org>; "Fu, Chao-Ying" <fu@mips.com>; "Thekkath, Radhika"
<radhika@mips.com>; "Stephens, Nigel" <nigel@mips.com>; "Arnaud Charlet"
<charlet@adacore.com>
Sent: Wednesday, October 04, 2006 3:19 AM
Subject: Re: Fixed-Point Arithmetic Project


> On Saturday 23 September 2006 17:08, Robert Dewar wrote:
> > Duncan Sands wrote:
> > >> We are working on a project to add fixed-point arithmetic support to
GCC.
> > >> A GCC project description page is available here
> > >> http://gcc.gnu.org/wiki/FixedPointArithmetic
> > >> and we will create a GCC branch in the near future. If you have
> > >> any suggestions or comments, please respond.
> > >
> > > I expect the Ada front-end people will be interested: the Ada language
> > > incorporates binary and decimal fixed point types.  AFAIK, it is all
> > > done using emulation at the moment.
> >
> > I don't know what emulation means here, obviously there is little
> > hardware support. Ada generates perfectly efficient fixed-point code,
> > but the code is generated in the front end. It might be possible
> > to share back end code if the semantics is exactly what Ada needs.
>
> Making sure the semantics matches what Ada needs is a good reason to get
> involved at this early stage.
>
> Ciao,
>
> Duncan.
>