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Re: IEEE128 binary float to decimal float conversion routines
- From: "Paul E. Murphy" <murphyp at linux dot vnet dot ibm dot com>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>, Steve Munroe <sjmunroe at us dot ibm dot com>, Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>, Michael R Meissner <mrmeissn at us dot ibm dot com>
- Date: Mon, 16 Nov 2015 17:45:20 -0600
- Subject: Re: IEEE128 binary float to decimal float conversion routines
- Authentication-results: sourceware.org; auth=none
- References: <564A16D5 dot 3020105 at linux dot vnet dot ibm dot com> <alpine dot DEB dot 2 dot 10 dot 1511161803500 dot 30498 at digraph dot polyomino dot org dot uk>
On 11/16/2015 12:24 PM, Joseph Myers wrote:
> On Mon, 16 Nov 2015, Paul E. Murphy wrote:
>
>> Hi Joseph,
>>
>> I think there may have been a question as to where the
>> conversion routines between IEEE 128 binary float and
>> decimal float should live.
>>
>> Observing existing precedent and machinery, I think
>> the appropriate place to house them is within libdfp.
>
> I think existing practice is that there's a copy of such functions in
> libgcc and another copy in libdfp - and maybe the libdfp version supports
> exceptions and rounding modes (software or hardware) but the libgcc
> version doesn't?
Thanks for pointing that out. libgcc implements a subset
of the API provided by libdfp. However, libdfp should have
better compliance and optimization for powerpc targets. They
take different approaches when converting formats, among other
things.
This opinion may not be shared, but we consider the libdfp
implementation primary, at least for dpd encoding.