import newlib-2000-02-17 snapshot

1 files changed, 73 insertions, 0 deletions

diff --git a/newlib/libm/math/sf_tanh.c b/newlib/libm/math/sf_tanh.c
new file mode 100644
index 000000000..ba9edf5c0
--- /dev/null
+++ b/newlib/libm/math/sf_tanh.c
@@ -0,0 +1,73 @@
+/* sf_tanh.c -- float version of s_tanh.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+#include "fdlibm.h"
+
+#ifdef __STDC__
+static const float one=1.0, two=2.0, tiny = 1.0e-30;
+#else
+static float one=1.0, two=2.0, tiny = 1.0e-30;
+#endif
+
+#ifdef __STDC__
+	float tanhf(float x)
+#else
+	float tanhf(x)
+	float x;
+#endif
+{
+	float t,z;
+	__int32_t jx,ix;
+
+	GET_FLOAT_WORD(jx,x);
+	ix = jx&0x7fffffff;
+
+    /* x is INF or NaN */
+	if(ix>=0x7f800000) { 
+	    if (jx>=0) return one/x+one;    /* tanh(+-inf)=+-1 */
+	    else       return one/x-one;    /* tanh(NaN) = NaN */
+	}
+
+    /* |x| < 22 */
+	if (ix < 0x41b00000) {		/* |x|<22 */
+	    if (ix<0x24000000) 		/* |x|<2**-55 */
+		return x*(one+x);    	/* tanh(small) = small */
+	    if (ix>=0x3f800000) {	/* |x|>=1  */
+		t = expm1f(two*fabsf(x));
+		z = one - two/(t+two);
+	    } else {
+	        t = expm1f(-two*fabsf(x));
+	        z= -t/(t+two);
+	    }
+    /* |x| > 22, return +-1 */
+	} else {
+	    z = one - tiny;		/* raised inexact flag */
+	}
+	return (jx>=0)? z: -z;
+}
+
+#ifdef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+	double tanh(double x)
+#else
+	double tanh(x)
+	double x;
+#endif
+{
+	return (double) tanhf((float) x);
+}
+
+#endif /* defined(_DOUBLE_IS_32BITS) */