RFA: Add implementation of cabsl()

[Nick Clifton]

Hi Guys,

  Attached is a patch that adds an implementation of the cabsl()
  function to newlib.  I foolishly thought that adding a function that
  just computes an absolute value would be easy, but boy was I wrong.
  It turns out that I had to add a whole lot of supporting functions,
  including a long double square root (sqrtl) and a long double
  hypotenuse (hypotl) function, as well as definitions of IEEE long
  double formats for a whole variety of architectures.  So the patch is
  actually quite large.  The good news is that (if the patch is
  acceptable) adding further long double math functions should be easier
  now that most of the architectural support is in place.

  One thing that might prove problematic is that the sqrtl() function
  currently only rounds up to the nearest bit, rather than trying to
  figure out the rounding mode currently in use and then applying that.
  My hope is that if this is considered to be a problem, it could be
  fixed by a follow up patch.  (Preferably written by someone who is more
  familiar with this kind of math than I am).

  Another problem I had was testing the patch.  I used an aarch64
  toolchain to test compiling code that used the functions, but the
  simulator I have is unable to run the code properly.  (This is due to
  problems with the simulator, which is currently under development).

  I tried to build an x86_64-pc-cygwin toolchain, but no matter what I
  did I could not get one to compile.  If I had more time I would look
  into this, but I need to get back to other work.

  In the end I build an x86_64-pc-elf toolchain, extracted the maths
  library from that and linked it into a test binary built natively on a
  x86_64 Linux host.  Cumbersome, but it worked, and the code tests
  alright, at least for the limited testing I performed.
  
  OK to apply ?

Cheers
  Nick

newlib/ChangeLog
2015-02-06  Nick Clifton  <nickc@redhat.com>

	* libc/include/complex.h (cabsl): Add prototype.
	(cimagl): Add prototype.
	(creall): Add prototype.
	* libc/include/ieeefp.h: Include float.h.
	(EXT_EXPBITS, EXT_FRACHBITS, EXT_FRACLBITS)
	(EXT_EXP_INFNAN. EXT_EXP_BIAS, EXT_FRACBITS): Define.
	(struct ieee_ext, union ieee_ext_u): New types for long double
	support.
	* libc/include/math.h (finitel): Add prototype.
	(hypotl): Add prototype.
	(sqrtl): Add prototype.
	* libm/common/Makefile.am (lsrc): Add sl_finite.c.
	* libm/common/Makefile.in: Regenerate.
	* libm/common/fdlibm.h (__ieee754_hypotl): Add prototype.
	* libm/common/hypotl.c (hypotl): Add implementation for when long
	double is larger than double.
	* libm/common/sqrtl.c (sqrtl): Likewise.
	* libm/common/sl_finite.c: New file.  Adds implementation of the
	finitel function.
	* libm/complex/Makefile.am (lsrc): Define.
	(libcomplex_la_SOURCES): Add lsrc.
	(lib_a_SOURCES): Add lsrc.
	* libm/complex/Makefile.in: Regenerate.
	* libm/complex/cabs.c: Add documentation of cabsl function.
	* libm/complex/cimag.c: Add documentation of cimagl function.
	* libm/complex/creall.c: Add documentation of creall function.
	* libm/complex/cabsl.c: New file.  Adds implementation of the
	cabsl function.
	* libm/complex/cimagl.c: New file.  Adds implementation of the
	cimagl function.
	* libm/complex/creakl.c: New file.  Adds implementation of the
	creall function.
	* libm/math/Makefile.am (lsrc): Define.
	(libmath_la_SOURCES): Add lsrc.
	(lib_a_SOURCES): Add lsrc.
	* libm/math/Makefile.in: Regenerate.
	* libm/math/el_hypot.c: New file.  Adds implementation of the
	__ieee754_hypotl function.

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