Add missing long double functions to Cygwin

This patch adds the long double functions missing in newlib to Cygwin.
Apart from some self-written additions (exp10l, finite{f,l}, isinf{f,l},
isnan{f,l}, pow10l) the files are taken from the Mingw-w64 math lib.
Minor changes were required, e.g. substitue _WIN64 with __x86_64__ and
fixing __FLT_RPT_DOMAIN/__FLT_RPT_ERANGE for Cygwin.

Cygwin:
	* math: New subdir with math functions.
	* Makefile.in (VPATH): Add math subdir.
	(MATH_OFILES): List of object files collected from building files in
	math subdir.
	(DLL_OFILES): Add $(MATH_OFILES).
	${CURDIR}/libm.a: Add $(MATH_OFILES) to build.
	* common.din: Add new functions from math subdir.
	* i686.din: Align to new math subdir.  Remove functions now commonly
	available.
	* x86_64.din: Ditto.
	* math.h: math.h wrapper to define mingw structs used in some files in
	math subdir.
	* include/cygwin/version.h: Bump API minor version.

newlib:
	* libc/include/complex.h: Add prototypes for complex long double
	functions.  Only define for Cygwin.
	* libc/include/math.h: Additionally enable prototypes of long double
	functions for Cygwin.  Add Cygwin-only prototypes for dreml, sincosl,
	exp10l and pow10l.  Explain why we don't add them to newlib.
	* libc/include/tgmath.h: Enable long double handling on Cygwin.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

1 files changed, 34 insertions, 0 deletions

diff --git a/winsup/cygwin/math/atanhl.c b/winsup/cygwin/math/atanhl.c
new file mode 100644
index 000000000..59eb1bd91
--- /dev/null
+++ b/winsup/cygwin/math/atanhl.c
@@ -0,0 +1,34 @@
+/**
+ * This file has no copyright assigned and is placed in the Public Domain.
+ * This file is part of the mingw-w64 runtime package.
+ * No warranty is given; refer to the file DISCLAIMER.PD within this package.
+ */
+#include <math.h>
+#include <errno.h>
+#include "fastmath.h"
+
+/* atanh (x) = 0.5 * log ((1.0 + x)/(1.0 - x)) */
+long double atanhl (long double x)
+{
+  long double z;
+  if (isnan (x))
+    return x;
+  z = fabsl (x);
+  if (z == 1.0L)
+    {
+      errno  = ERANGE;
+      return (x > 0 ? INFINITY : -INFINITY);
+    }
+  if ( z > 1.0L)
+    {
+      errno = EDOM;
+      return nanl("");
+    }
+  /* Rearrange formula to avoid precision loss for small x.
+  atanh(x) = 0.5 * log ((1.0 + x)/(1.0 - x))
+ 	   = 0.5 * log1p ((1.0 + x)/(1.0 - x) - 1.0)
+           = 0.5 * log1p ((1.0 + x - 1.0 + x) /(1.0 - x)) 
+           = 0.5 * log1p ((2.0 * x ) / (1.0 - x))  */
+  z = 0.5L * __fast_log1pl ((z + z) / (1.0L - z));
+  return x >= 0 ? z : -z;
+}