IEEE128 binary float to decimal float conversion routines

[Joseph Myers]

On Fri, 18 Dec 2015, Steven Munroe wrote:

> > Well, I'd think the starting point is to implement operations following 
> > the correct semantics, which are quite clear in both TR 24732:2009 and TS 
> > 18661-2: as per IEEE 754-2008, conversions are correctly rounded with 
> > correct exceptions.  
> 
> Then you should be specific! Specific examples with test cases.

https://github.com/libdfp/libdfp/issues/29
https://github.com/libdfp/libdfp/issues/30
https://github.com/libdfp/libdfp/issues/31
https://github.com/libdfp/libdfp/issues/32
https://github.com/libdfp/libdfp/issues/33
https://github.com/libdfp/libdfp/issues/34

All include testcases, tested with current git libdfp on POWER8 
little-endian.  Five of the six work correctly with the libgcc 
conversions.  All should be understood to be likely to apply to most of 
the binary/decimal conversions in libdfp, in both directions, not just to 
the conversions from _Decimal128 to double used to illustrate them, 
because of the similarity of code used for different conversions.  I think 
together those issues provide reasonable coverage of the problems with 
libdfp conversions that I've identified in this thread.

-- 
Joseph S. Myers
joseph@codesourcery.com