initial check-in, version 0.5.0 v0.5.0

1 files changed, 122 insertions, 0 deletions

diff --git a/src/math/s_expm1f.c b/src/math/s_expm1f.c
new file mode 100644
index 00000000..b22cf0f9
--- /dev/null
+++ b/src/math/s_expm1f.c
@@ -0,0 +1,122 @@
+/* s_expm1f.c -- float version of s_expm1.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 <math.h>
+#include "math_private.h"
+
+static const float
+one             = 1.0,
+huge            = 1.0e+30,
+tiny            = 1.0e-30,
+o_threshold     = 8.8721679688e+01,/* 0x42b17180 */
+ln2_hi          = 6.9313812256e-01,/* 0x3f317180 */
+ln2_lo          = 9.0580006145e-06,/* 0x3717f7d1 */
+invln2          = 1.4426950216e+00,/* 0x3fb8aa3b */
+        /* scaled coefficients related to expm1 */
+Q1  =  -3.3333335072e-02, /* 0xbd088889 */
+Q2  =   1.5873016091e-03, /* 0x3ad00d01 */
+Q3  =  -7.9365076090e-05, /* 0xb8a670cd */
+Q4  =   4.0082177293e-06, /* 0x36867e54 */
+Q5  =  -2.0109921195e-07; /* 0xb457edbb */
+
+float
+expm1f(float x)
+{
+        float y,hi,lo,c=0.0,t,e,hxs,hfx,r1;
+        int32_t k,xsb;
+        uint32_t hx;
+
+        GET_FLOAT_WORD(hx,x);
+        xsb = hx&0x80000000;            /* sign bit of x */
+        if(xsb==0) y=x; else y= -x;     /* y = |x| */
+        hx &= 0x7fffffff;               /* high word of |x| */
+
+    /* filter out huge and non-finite argument */
+        if(hx >= 0x4195b844) {                  /* if |x|>=27*ln2 */
+            if(hx >= 0x42b17218) {              /* if |x|>=88.721... */
+                if(hx>0x7f800000)
+                    return x+x;          /* NaN */
+                if(hx==0x7f800000)
+                    return (xsb==0)? x:-1.0;/* exp(+-inf)={inf,-1} */
+                if(x > o_threshold) return huge*huge; /* overflow */
+            }
+            if(xsb!=0) { /* x < -27*ln2, return -1.0 with inexact */
+                if(x+tiny<(float)0.0)   /* raise inexact */
+                return tiny-one;        /* return -1 */
+            }
+        }
+
+    /* argument reduction */
+        if(hx > 0x3eb17218) {           /* if  |x| > 0.5 ln2 */
+            if(hx < 0x3F851592) {       /* and |x| < 1.5 ln2 */
+                if(xsb==0)
+                    {hi = x - ln2_hi; lo =  ln2_lo;  k =  1;}
+                else
+                    {hi = x + ln2_hi; lo = -ln2_lo;  k = -1;}
+            } else {
+                k  = invln2*x+((xsb==0)?(float)0.5:(float)-0.5);
+                t  = k;
+                hi = x - t*ln2_hi;      /* t*ln2_hi is exact here */
+                lo = t*ln2_lo;
+            }
+            x  = hi - lo;
+            c  = (hi-x)-lo;
+        }
+        else if(hx < 0x33000000) {      /* when |x|<2**-25, return x */
+            t = huge+x; /* return x with inexact flags when x!=0 */
+            return x - (t-(huge+x));
+        }
+        else k = 0;
+
+    /* x is now in primary range */
+        hfx = (float)0.5*x;
+        hxs = x*hfx;
+        r1 = one+hxs*(Q1+hxs*(Q2+hxs*(Q3+hxs*(Q4+hxs*Q5))));
+        t  = (float)3.0-r1*hfx;
+        e  = hxs*((r1-t)/((float)6.0 - x*t));
+        if(k==0) return x - (x*e-hxs);          /* c is 0 */
+        else {
+            e  = (x*(e-c)-c);
+            e -= hxs;
+            if(k== -1) return (float)0.5*(x-e)-(float)0.5;
+            if(k==1) {
+                if(x < (float)-0.25) return -(float)2.0*(e-(x+(float)0.5));
+                else          return  one+(float)2.0*(x-e);
+            }
+            if (k <= -2 || k>56) {   /* suffice to return exp(x)-1 */
+                int32_t i;
+                y = one-(e-x);
+                GET_FLOAT_WORD(i,y);
+                SET_FLOAT_WORD(y,i+(k<<23));    /* add k to y's exponent */
+                return y-one;
+            }
+            t = one;
+            if(k<23) {
+                int32_t i;
+                SET_FLOAT_WORD(t,0x3f800000 - (0x1000000>>k)); /* t=1-2^-k */
+                y = t-(e-x);
+                GET_FLOAT_WORD(i,y);
+                SET_FLOAT_WORD(y,i+(k<<23));    /* add k to y's exponent */
+           } else {
+                int32_t i;
+                SET_FLOAT_WORD(t,((0x7f-k)<<23));       /* 2^-k */
+                y = x-(e+t);
+                y += one;
+                GET_FLOAT_WORD(i,y);
+                SET_FLOAT_WORD(y,i+(k<<23));    /* add k to y's exponent */
+            }
+        }
+        return y;
+}