[Beignet] [PATCH] backend: add double version of tanh

[rander]

	cp from fdlibm and pass the cft after refined

Signed-off-by: rander <rander.wang at intel.com>
---
 backend/src/libocl/tmpl/ocl_math_common.tmpl.cl | 34 +++++++++++++++++++++++++
 backend/src/libocl/tmpl/ocl_math_common.tmpl.h  |  1 +
 2 files changed, 35 insertions(+)

diff --git a/backend/src/libocl/tmpl/ocl_math_common.tmpl.cl b/backend/src/libocl/tmpl/ocl_math_common.tmpl.cl
index a705e2f..c370864 100644
--- a/backend/src/libocl/tmpl/ocl_math_common.tmpl.cl
+++ b/backend/src/libocl/tmpl/ocl_math_common.tmpl.cl
@@ -1999,6 +1999,40 @@ OVERLOADABLE double tan(double x)
 	}
 }
 
+OVERLOADABLE double tanh(double x)
+{
+	double one=1.0, two=2.0, tiny = 1.0e-300;
+	double t,z;
+	int jx,ix;
+
+	/* High word of |x|. */
+	jx = __HI(x);
+	ix = jx&0x7fffffff;
+
+	/* x is INF or NaN */
+	if(ix>=0x7ff00000) {
+		if (jx>=0) return one/x+one;	/* tanh(+-inf)=+-1 */
+		else	   return one/x-one;	/* tanh(NaN) = NaN */
+	}
+
+	/* |x| < 22 */
+	if (ix < 0x40360000) {		/* |x|<22 */
+		if (ix<0x3c800000) 		/* |x|<2**-55 */
+		return x*(one+x);		/* tanh(small) = small */
+		if (ix>=0x3ff00000) {	/* |x|>=1  */
+		t = expm1(two*fabs(x));
+		z = one - two/(t+two);
+		} else {
+			t = expm1(-two*fabs(x));
+			z= -t/(t+two);
+		}
+	/* |x| > 22, return +-1 */
+	} else {
+		z = one - tiny;		/* raised inexact flag */
+	}
+	return (jx>=0)? z: -z;
+}
+
 OVERLOADABLE double trunc(double x)
 {
 	double ret = floor(fabs(x));
diff --git a/backend/src/libocl/tmpl/ocl_math_common.tmpl.h b/backend/src/libocl/tmpl/ocl_math_common.tmpl.h
index 9ac3b31..471f866 100644
--- a/backend/src/libocl/tmpl/ocl_math_common.tmpl.h
+++ b/backend/src/libocl/tmpl/ocl_math_common.tmpl.h
@@ -58,6 +58,7 @@ OVERLOADABLE double sin(double x);
 OVERLOADABLE double sinh(double x);
 OVERLOADABLE double sqrt(double x);
 OVERLOADABLE double tan(double x);
+OVERLOADABLE double tanh(double x);
 OVERLOADABLE double trunc(double x);
 
 
-- 
2.7.4