J.T. Conklin's latest version of the Sun math library.

-- Begin comments from J.T. Conklin:
The most significant improvement is the addition of "float" versions
of the math functions that take float arguments, return floats, and do
all operations in floating point.  This doesn't help (performance)
much on the i386, but they are still nice to have.

The float versions were orginally done by Cygnus' Ian Taylor when
fdlibm was integrated into the libm we support for embedded systems.
I gave Ian a copy of my libm as a starting point since I had already
fixed a lot of bugs & problems in Sun's original code.  After he was
done, I cleaned it up a bit and integrated the changes back into my
libm.
-- End comments

Reviewed by:	jkh
Submitted by:	jtc

1 files changed, 312 insertions, 0 deletions

diff --git a/lib/msun/src/e_pow.c b/lib/msun/src/e_pow.c
new file mode 100644
index 0000000..80ac795
--- /dev/null
+++ b/lib/msun/src/e_pow.c
@@ -0,0 +1,312 @@
+/* @(#)e_pow.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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[] = "$Id: e_pow.c,v 1.5 1994/08/18 23:05:51 jtc Exp $";
+#endif
+
+/* __ieee754_pow(x,y) return x**y
+ *
+ *		      n
+ * Method:  Let x =  2   * (1+f)
+ *	1. Compute and return log2(x) in two pieces:
+ *		log2(x) = w1 + w2,
+ *	   where w1 has 53-24 = 29 bit trailing zeros.
+ *	2. Perform y*log2(x) = n+y' by simulating muti-precision 
+ *	   arithmetic, where |y'|<=0.5.
+ *	3. Return x**y = 2**n*exp(y'*log2)
+ *
+ * Special cases:
+ *	1.  (anything) ** 0  is 1
+ *	2.  (anything) ** 1  is itself
+ *	3.  (anything) ** NAN is NAN
+ *	4.  NAN ** (anything except 0) is NAN
+ *	5.  +-(|x| > 1) **  +INF is +INF
+ *	6.  +-(|x| > 1) **  -INF is +0
+ *	7.  +-(|x| < 1) **  +INF is +0
+ *	8.  +-(|x| < 1) **  -INF is +INF
+ *	9.  +-1         ** +-INF is NAN
+ *	10. +0 ** (+anything except 0, NAN)               is +0
+ *	11. -0 ** (+anything except 0, NAN, odd integer)  is +0
+ *	12. +0 ** (-anything except 0, NAN)               is +INF
+ *	13. -0 ** (-anything except 0, NAN, odd integer)  is +INF
+ *	14. -0 ** (odd integer) = -( +0 ** (odd integer) )
+ *	15. +INF ** (+anything except 0,NAN) is +INF
+ *	16. +INF ** (-anything except 0,NAN) is +0
+ *	17. -INF ** (anything)  = -0 ** (-anything)
+ *	18. (-anything) ** (integer) is (-1)**(integer)*(+anything**integer)
+ *	19. (-anything except 0 and inf) ** (non-integer) is NAN
+ *
+ * Accuracy:
+ *	pow(x,y) returns x**y nearly rounded. In particular
+ *			pow(integer,integer)
+ *	always returns the correct integer provided it is 
+ *	representable.
+ *
+ * Constants :
+ * The hexadecimal values are the intended ones for the following 
+ * constants. The decimal values may be used, provided that the 
+ * compiler will convert from decimal to binary accurately enough 
+ * to produce the hexadecimal values shown.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double 
+#else
+static double 
+#endif
+bp[] = {1.0, 1.5,},
+dp_h[] = { 0.0, 5.84962487220764160156e-01,}, /* 0x3FE2B803, 0x40000000 */
+dp_l[] = { 0.0, 1.35003920212974897128e-08,}, /* 0x3E4CFDEB, 0x43CFD006 */
+zero    =  0.0,
+one	=  1.0,
+two	=  2.0,
+two53	=  9007199254740992.0,	/* 0x43400000, 0x00000000 */
+huge	=  1.0e300,
+tiny    =  1.0e-300,
+	/* poly coefs for (3/2)*(log(x)-2s-2/3*s**3 */
+L1  =  5.99999999999994648725e-01, /* 0x3FE33333, 0x33333303 */
+L2  =  4.28571428578550184252e-01, /* 0x3FDB6DB6, 0xDB6FABFF */
+L3  =  3.33333329818377432918e-01, /* 0x3FD55555, 0x518F264D */
+L4  =  2.72728123808534006489e-01, /* 0x3FD17460, 0xA91D4101 */
+L5  =  2.30660745775561754067e-01, /* 0x3FCD864A, 0x93C9DB65 */
+L6  =  2.06975017800338417784e-01, /* 0x3FCA7E28, 0x4A454EEF */
+P1   =  1.66666666666666019037e-01, /* 0x3FC55555, 0x5555553E */
+P2   = -2.77777777770155933842e-03, /* 0xBF66C16C, 0x16BEBD93 */
+P3   =  6.61375632143793436117e-05, /* 0x3F11566A, 0xAF25DE2C */
+P4   = -1.65339022054652515390e-06, /* 0xBEBBBD41, 0xC5D26BF1 */
+P5   =  4.13813679705723846039e-08, /* 0x3E663769, 0x72BEA4D0 */
+lg2  =  6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
+lg2_h  =  6.93147182464599609375e-01, /* 0x3FE62E43, 0x00000000 */
+lg2_l  = -1.90465429995776804525e-09, /* 0xBE205C61, 0x0CA86C39 */
+ovt =  8.0085662595372944372e-0017, /* -(1024-log2(ovfl+.5ulp)) */
+cp    =  9.61796693925975554329e-01, /* 0x3FEEC709, 0xDC3A03FD =2/(3ln2) */
+cp_h  =  9.61796700954437255859e-01, /* 0x3FEEC709, 0xE0000000 =(float)cp */
+cp_l  = -7.02846165095275826516e-09, /* 0xBE3E2FE0, 0x145B01F5 =tail of cp_h*/
+ivln2    =  1.44269504088896338700e+00, /* 0x3FF71547, 0x652B82FE =1/ln2 */
+ivln2_h  =  1.44269502162933349609e+00, /* 0x3FF71547, 0x60000000 =24b 1/ln2*/
+ivln2_l  =  1.92596299112661746887e-08; /* 0x3E54AE0B, 0xF85DDF44 =1/ln2 tail*/
+
+#ifdef __STDC__
+	double __ieee754_pow(double x, double y)
+#else
+	double __ieee754_pow(x,y)
+	double x, y;
+#endif
+{
+	double z,ax,z_h,z_l,p_h,p_l;
+	double y1,t1,t2,r,s,t,u,v,w;
+	int32_t i,j,k,yisint,n;
+	int32_t hx,hy,ix,iy;
+	u_int32_t lx,ly;
+
+	EXTRACT_WORDS(hx,lx,x);
+	EXTRACT_WORDS(hy,ly,y);
+	ix = hx&0x7fffffff;  iy = hy&0x7fffffff;
+
+    /* y==zero: x**0 = 1 */
+	if((iy|ly)==0) return one; 	
+
+    /* +-NaN return x+y */
+	if(ix > 0x7ff00000 || ((ix==0x7ff00000)&&(lx!=0)) ||
+	   iy > 0x7ff00000 || ((iy==0x7ff00000)&&(ly!=0))) 
+		return x+y;	
+
+    /* determine if y is an odd int when x < 0
+     * yisint = 0	... y is not an integer
+     * yisint = 1	... y is an odd int
+     * yisint = 2	... y is an even int
+     */
+	yisint  = 0;
+	if(hx<0) {	
+	    if(iy>=0x43400000) yisint = 2; /* even integer y */
+	    else if(iy>=0x3ff00000) {
+		k = (iy>>20)-0x3ff;	   /* exponent */
+		if(k>20) {
+		    j = ly>>(52-k);
+		    if((j<<(52-k))==ly) yisint = 2-(j&1);
+		} else if(ly==0) {
+		    j = iy>>(20-k);
+		    if((j<<(20-k))==iy) yisint = 2-(j&1);
+		}
+	    }		
+	} 
+
+    /* special value of y */
+	if(ly==0) { 	
+	    if (iy==0x7ff00000) {	/* y is +-inf */
+	        if(((ix-0x3ff00000)|lx)==0)
+		    return  y - y;	/* inf**+-1 is NaN */
+	        else if (ix >= 0x3ff00000)/* (|x|>1)**+-inf = inf,0 */
+		    return (hy>=0)? y: zero;
+	        else			/* (|x|<1)**-,+inf = inf,0 */
+		    return (hy<0)?-y: zero;
+	    } 
+	    if(iy==0x3ff00000) {	/* y is  +-1 */
+		if(hy<0) return one/x; else return x;
+	    }
+	    if(hy==0x40000000) return x*x; /* y is  2 */
+	    if(hy==0x3fe00000) {	/* y is  0.5 */
+		if(hx>=0)	/* x >= +0 */
+		return sqrt(x);	
+	    }
+	}
+
+	ax   = fabs(x);
+    /* special value of x */
+	if(lx==0) {
+	    if(ix==0x7ff00000||ix==0||ix==0x3ff00000){
+		z = ax;			/*x is +-0,+-inf,+-1*/
+		if(hy<0) z = one/z;	/* z = (1/|x|) */
+		if(hx<0) {
+		    if(((ix-0x3ff00000)|yisint)==0) {
+			z = (z-z)/(z-z); /* (-1)**non-int is NaN */
+		    } else if(yisint==1) 
+			z = -z;		/* (x<0)**odd = -(|x|**odd) */
+		}
+		return z;
+	    }
+	}
+    
+    /* (x<0)**(non-int) is NaN */
+    /* CYGNUS LOCAL: This used to be
+	if((((hx>>31)+1)|yisint)==0) return (x-x)/(x-x);
+       but ANSI C says a right shift of a signed negative quantity is
+       implementation defined.  */
+	if(((((u_int32_t)hx>>31)-1)|yisint)==0) return (x-x)/(x-x);
+
+    /* |y| is huge */
+	if(iy>0x41e00000) { /* if |y| > 2**31 */
+	    if(iy>0x43f00000){	/* if |y| > 2**64, must o/uflow */
+		if(ix<=0x3fefffff) return (hy<0)? huge*huge:tiny*tiny;
+		if(ix>=0x3ff00000) return (hy>0)? huge*huge:tiny*tiny;
+	    }
+	/* over/underflow if x is not close to one */
+	    if(ix<0x3fefffff) return (hy<0)? huge*huge:tiny*tiny;
+	    if(ix>0x3ff00000) return (hy>0)? huge*huge:tiny*tiny;
+	/* now |1-x| is tiny <= 2**-20, suffice to compute 
+	   log(x) by x-x^2/2+x^3/3-x^4/4 */
+	    t = x-1;		/* t has 20 trailing zeros */
+	    w = (t*t)*(0.5-t*(0.3333333333333333333333-t*0.25));
+	    u = ivln2_h*t;	/* ivln2_h has 21 sig. bits */
+	    v = t*ivln2_l-w*ivln2;
+	    t1 = u+v;
+	    SET_LOW_WORD(t1,0);
+	    t2 = v-(t1-u);
+	} else {
+	    double s2,s_h,s_l,t_h,t_l;
+	    n = 0;
+	/* take care subnormal number */
+	    if(ix<0x00100000)
+		{ax *= two53; n -= 53; GET_HIGH_WORD(ix,ax); }
+	    n  += ((ix)>>20)-0x3ff;
+	    j  = ix&0x000fffff;
+	/* determine interval */
+	    ix = j|0x3ff00000;		/* normalize ix */
+	    if(j<=0x3988E) k=0;		/* |x|<sqrt(3/2) */
+	    else if(j<0xBB67A) k=1;	/* |x|<sqrt(3)   */
+	    else {k=0;n+=1;ix -= 0x00100000;}
+	    SET_HIGH_WORD(ax,ix);
+
+	/* compute s = s_h+s_l = (x-1)/(x+1) or (x-1.5)/(x+1.5) */
+	    u = ax-bp[k];		/* bp[0]=1.0, bp[1]=1.5 */
+	    v = one/(ax+bp[k]);
+	    s = u*v;
+	    s_h = s;
+	    SET_LOW_WORD(s_h,0);
+	/* t_h=ax+bp[k] High */
+	    t_h = zero;
+	    SET_HIGH_WORD(t_h,((ix>>1)|0x20000000)+0x00080000+(k<<18));
+	    t_l = ax - (t_h-bp[k]);
+	    s_l = v*((u-s_h*t_h)-s_h*t_l);
+	/* compute log(ax) */
+	    s2 = s*s;
+	    r = s2*s2*(L1+s2*(L2+s2*(L3+s2*(L4+s2*(L5+s2*L6)))));
+	    r += s_l*(s_h+s);
+	    s2  = s_h*s_h;
+	    t_h = 3.0+s2+r;
+	    SET_LOW_WORD(t_h,0);
+	    t_l = r-((t_h-3.0)-s2);
+	/* u+v = s*(1+...) */
+	    u = s_h*t_h;
+	    v = s_l*t_h+t_l*s;
+	/* 2/(3log2)*(s+...) */
+	    p_h = u+v;
+	    SET_LOW_WORD(p_h,0);
+	    p_l = v-(p_h-u);
+	    z_h = cp_h*p_h;		/* cp_h+cp_l = 2/(3*log2) */
+	    z_l = cp_l*p_h+p_l*cp+dp_l[k];
+	/* log2(ax) = (s+..)*2/(3*log2) = n + dp_h + z_h + z_l */
+	    t = (double)n;
+	    t1 = (((z_h+z_l)+dp_h[k])+t);
+	    SET_LOW_WORD(t1,0);
+	    t2 = z_l-(((t1-t)-dp_h[k])-z_h);
+	}
+
+	s = one; /* s (sign of result -ve**odd) = -1 else = 1 */
+	if(((((u_int32_t)hx>>31)-1)|(yisint-1))==0)
+	    s = -one;/* (-ve)**(odd int) */
+
+    /* split up y into y1+y2 and compute (y1+y2)*(t1+t2) */
+	y1  = y;
+	SET_LOW_WORD(y1,0);
+	p_l = (y-y1)*t1+y*t2;
+	p_h = y1*t1;
+	z = p_l+p_h;
+	EXTRACT_WORDS(j,i,z);
+	if (j>=0x40900000) {				/* z >= 1024 */
+	    if(((j-0x40900000)|i)!=0)			/* if z > 1024 */
+		return s*huge*huge;			/* overflow */
+	    else {
+		if(p_l+ovt>z-p_h) return s*huge*huge;	/* overflow */
+	    }
+	} else if((j&0x7fffffff)>=0x4090cc00 ) {	/* z <= -1075 */
+	    if(((j-0xc090cc00)|i)!=0) 		/* z < -1075 */
+		return s*tiny*tiny;		/* underflow */
+	    else {
+		if(p_l<=z-p_h) return s*tiny*tiny;	/* underflow */
+	    }
+	}
+    /*
+     * compute 2**(p_h+p_l)
+     */
+	i = j&0x7fffffff;
+	k = (i>>20)-0x3ff;
+	n = 0;
+	if(i>0x3fe00000) {		/* if |z| > 0.5, set n = [z+0.5] */
+	    n = j+(0x00100000>>(k+1));
+	    k = ((n&0x7fffffff)>>20)-0x3ff;	/* new k for n */
+	    t = zero;
+	    SET_HIGH_WORD(t,n&~(0x000fffff>>k));
+	    n = ((n&0x000fffff)|0x00100000)>>(20-k);
+	    if(j<0) n = -n;
+	    p_h -= t;
+	} 
+	t = p_l+p_h;
+	SET_LOW_WORD(t,0);
+	u = t*lg2_h;
+	v = (p_l-(t-p_h))*lg2+t*lg2_l;
+	z = u+v;
+	w = v-(z-u);
+	t  = z*z;
+	t1  = z - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
+	r  = (z*t1)/(t1-two)-(w+z*w);
+	z  = one-(r-z);
+	GET_HIGH_WORD(j,z);
+	j += (n<<20);
+	if((j>>20)<=0) z = scalbn(z,n);	/* subnormal output */
+	else SET_HIGH_WORD(z,j);
+	return s*z;
+}