1 files changed, 97 insertions, 0 deletions
diff --git a/modules/fdlibm/src/e_expf.cpp b/modules/fdlibm/src/e_expf.cpp
new file mode 100644
index 0000000000..dd5b665d6f
--- /dev/null
+++ b/modules/fdlibm/src/e_expf.cpp
@@ -0,0 +1,97 @@
+/* e_expf.c -- float version of e_exp.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 <sys/cdefs.h>
+//__FBSDID("$FreeBSD$");
+
+#include <float.h>
+
+#include "math_private.h"
+
+static const float
+one	= 1.0,
+halF[2]	= {0.5,-0.5,},
+o_threshold=  8.8721679688e+01,  /* 0x42b17180 */
+u_threshold= -1.0397208405e+02,  /* 0xc2cff1b5 */
+ln2HI[2]   ={ 6.9314575195e-01,		/* 0x3f317200 */
+	     -6.9314575195e-01,},	/* 0xbf317200 */
+ln2LO[2]   ={ 1.4286067653e-06,  	/* 0x35bfbe8e */
+	     -1.4286067653e-06,},	/* 0xb5bfbe8e */
+invln2 =  1.4426950216e+00, 		/* 0x3fb8aa3b */
+/*
+ * Domain [-0.34568, 0.34568], range ~[-4.278e-9, 4.447e-9]:
+ * |x*(exp(x)+1)/(exp(x)-1) - p(x)| < 2**-27.74
+ */
+P1 =  1.6666625440e-1,		/*  0xaaaa8f.0p-26 */
+P2 = -2.7667332906e-3;		/* -0xb55215.0p-32 */
+
+static volatile float
+huge	= 1.0e+30,
+twom100 = 7.8886090522e-31;      /* 2**-100=0x0d800000 */
+
+float
+__ieee754_expf(float x)
+{
+	float y,hi=0.0,lo=0.0,c,t,twopk;
+	int32_t k=0,xsb;
+	u_int32_t hx;
+
+	GET_FLOAT_WORD(hx,x);
+	xsb = (hx>>31)&1;		/* sign bit of x */
+	hx &= 0x7fffffff;		/* high word of |x| */
+
+    /* filter out non-finite argument */
+	if(hx >= 0x42b17218) {			/* if |x|>=88.721... */
+	    if(hx>0x7f800000)
+		 return x+x;	 		/* NaN */
+            if(hx==0x7f800000)
+		return (xsb==0)? x:0.0;		/* exp(+-inf)={inf,0} */
+	    if(x > o_threshold) return huge*huge; /* overflow */
+	    if(x < u_threshold) return twom100*twom100; /* underflow */
+	}
+
+    /* argument reduction */
+	if(hx > 0x3eb17218) {		/* if  |x| > 0.5 ln2 */
+	    if(hx < 0x3F851592) {	/* and |x| < 1.5 ln2 */
+		hi = x-ln2HI[xsb]; lo=ln2LO[xsb]; k = 1-xsb-xsb;
+	    } else {
+		k  = invln2*x+halF[xsb];
+		t  = k;
+		hi = x - t*ln2HI[0];	/* t*ln2HI is exact here */
+		lo = t*ln2LO[0];
+	    }
+	    STRICT_ASSIGN(float, x, hi - lo);
+	}
+	else if(hx < 0x39000000)  {	/* when |x|<2**-14 */
+	    if(huge+x>one) return one+x;/* trigger inexact */
+	}
+	else k = 0;
+
+    /* x is now in primary range */
+	t  = x*x;
+	if(k >= -125)
+	    SET_FLOAT_WORD(twopk,((u_int32_t)(0x7f+k))<<23);
+	else
+	    SET_FLOAT_WORD(twopk,((u_int32_t)(0x7f+(k+100)))<<23);
+	c  = x - t*(P1+t*P2);
+	if(k==0) 	return one-((x*c)/(c-(float)2.0)-x);
+	else 		y = one-((lo-(x*c)/((float)2.0-c))-hi);
+	if(k >= -125) {
+	    if(k==128) return y*2.0F*0x1p127F;
+	    return y*twopk;
+	} else {
+	    return y*twopk*twom100;
+	}
+}