Implement cexpl

[Steve Kargl]

On Sun, Feb 03, 2019 at 09:30:56AM -0800, Steve Kargl wrote:
> The following patch implements cexpl() for ld80 and ld128 architectures.
> 
> The kernel files for large x are named ld{80,128}/k_cexpl.c to avoid
> confusion with the ld{80,128}/k_expl.h files.
> 
> I do not have access to ld128, so the ld128 does not use bit twiddling.
> I cannot test the ld128 implementation, but I believe that it works
> (for some definition of work).
> 

I forgot to mention that the initial files under ld{80,128} where
created via

svn cp src/k_exp.c ld80/k_cexpl.c
svn cp src/s_cexp.c ld80/s_cexpl.c
svn cp src/k_exp.c ld128/k_cexpl.c
svn cp src/s_cexp.c ld128/s_cexpl.c

so the diff is not against an empty file; but against the 
copied files.

-- 
Steve