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Re: RFC: Add BID as a configure time option for DFP
- From: Janis Johnson <janis187 at us dot ibm dot com>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: gcc at gcc dot gnu dot org, marius dot cornea at intel dot com, evandro dot menezes at amd dot com, bje at au1 dot ibm dot com
- Date: Wed, 10 Jan 2007 14:10:58 -0800
- Subject: Re: RFC: Add BID as a configure time option for DFP
- References: <20070110194045.GA22005@lucon.org>
On Wed, Jan 10, 2007 at 11:40:46AM -0800, H. J. Lu wrote:
> Both AMD and Intel like to have BID as a configure time option
> for DFP. Intel is planning to contribute a complete BID runtime
> library, which can be used by executables generate by gcc.
>
> As the first step, we'd like to contribute a BID<->DPD library so that
> BID can be used with libdecnumber by executables generate by gcc
> before the complete BID runtime library is ready.
>
> Any comments?
libdecnumber doesn't use DPD (densely packed decimal), it uses the
decNumber format. Functions in libgcc convert from DPD to decNumber,
call into libdecnumber to do computations, and then convert the result
back to DPD. It's all parameterized in dfp-bit.[ch], so replacing
conversions between decNumber structs and DPD with conversions between
decNumber structs and BID (binary integer decimal) should be
straightforward; I don't think there's any need to convert between BID
and DPD to use libdecnumber.
If all x86* targets will use BID then there's no need for a configure
option. Initial support using DPD for x86* was a proof of concept, I
doubt that anyone would care if you replace it with BID support.
Janis