1 files changed, 107 insertions, 0 deletions
diff --git a/libm/src/s_log1pf.c b/libm/src/s_log1pf.c
new file mode 100644
index 0000000..8364da0
--- /dev/null
+++ b/libm/src/s_log1pf.c
@@ -0,0 +1,107 @@
+/* s_log1pf.c -- float version of s_log1p.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.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_log1pf.c,v 1.9 2005/12/04 12:30:44 bde Exp $";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+static const float
+ln2_hi =   6.9313812256e-01,	/* 0x3f317180 */
+ln2_lo =   9.0580006145e-06,	/* 0x3717f7d1 */
+two25 =    3.355443200e+07,	/* 0x4c000000 */
+Lp1 = 6.6666668653e-01,	/* 3F2AAAAB */
+Lp2 = 4.0000000596e-01,	/* 3ECCCCCD */
+Lp3 = 2.8571429849e-01, /* 3E924925 */
+Lp4 = 2.2222198546e-01, /* 3E638E29 */
+Lp5 = 1.8183572590e-01, /* 3E3A3325 */
+Lp6 = 1.5313838422e-01, /* 3E1CD04F */
+Lp7 = 1.4798198640e-01; /* 3E178897 */
+
+static const float zero = 0.0;
+
+float
+log1pf(float x)
+{
+	float hfsq,f,c,s,z,R,u;
+	int32_t k,hx,hu,ax;
+
+	GET_FLOAT_WORD(hx,x);
+	ax = hx&0x7fffffff;
+
+	k = 1;
+	if (hx < 0x3ed413d0) {			/* 1+x < sqrt(2)+  */
+	    if(ax>=0x3f800000) {		/* x <= -1.0 */
+		if(x==(float)-1.0) return -two25/zero; /* log1p(-1)=+inf */
+		else return (x-x)/(x-x);	/* log1p(x<-1)=NaN */
+	    }
+	    if(ax<0x31000000) {			/* |x| < 2**-29 */
+		if(two25+x>zero			/* raise inexact */
+	            &&ax<0x24800000) 		/* |x| < 2**-54 */
+		    return x;
+		else
+		    return x - x*x*(float)0.5;
+	    }
+	    if(hx>0||hx<=((int32_t)0xbe95f619)) {
+		k=0;f=x;hu=1;}		/* sqrt(2)/2- <= 1+x < sqrt(2)+ */
+	}
+	if (hx >= 0x7f800000) return x+x;
+	if(k!=0) {
+	    if(hx<0x5a000000) {
+		*(volatile float *)&u = (float)1.0+x;
+		GET_FLOAT_WORD(hu,u);
+	        k  = (hu>>23)-127;
+		/* correction term */
+	        c  = (k>0)? (float)1.0-(u-x):x-(u-(float)1.0);
+		c /= u;
+	    } else {
+		u  = x;
+		GET_FLOAT_WORD(hu,u);
+	        k  = (hu>>23)-127;
+		c  = 0;
+	    }
+	    hu &= 0x007fffff;
+	    /*
+	     * The approximation to sqrt(2) used in thresholds is not
+	     * critical.  However, the ones used above must give less
+	     * strict bounds than the one here so that the k==0 case is
+	     * never reached from here, since here we have committed to
+	     * using the correction term but don't use it if k==0.
+	     */
+	    if(hu<0x3504f4) {			/* u < sqrt(2) */
+	        SET_FLOAT_WORD(u,hu|0x3f800000);/* normalize u */
+	    } else {
+	        k += 1;
+		SET_FLOAT_WORD(u,hu|0x3f000000);	/* normalize u/2 */
+	        hu = (0x00800000-hu)>>2;
+	    }
+	    f = u-(float)1.0;
+	}
+	hfsq=(float)0.5*f*f;
+	if(hu==0) {	/* |f| < 2**-20 */
+	    if(f==zero) if(k==0) return zero;
+			else {c += k*ln2_lo; return k*ln2_hi+c;}
+	    R = hfsq*((float)1.0-(float)0.66666666666666666*f);
+	    if(k==0) return f-R; else
+	    	     return k*ln2_hi-((R-(k*ln2_lo+c))-f);
+	}
+ 	s = f/((float)2.0+f);
+	z = s*s;
+	R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7))))));
+	if(k==0) return f-(hfsq-s*(hfsq+R)); else
+		 return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f);
+}