+++ /dev/null
-/* e_logf.c -- float version of e_log.c.
- * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
- * adapted for log2 by Ulrich Drepper <drepper@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"
-
-#ifdef __STDC__
-static const float
-#else
-static float
-#endif
-ln2 = 0.69314718055994530942,
-two25 = 3.355443200e+07, /* 0x4c000000 */
-Lg1 = 6.6666668653e-01, /* 3F2AAAAB */
-Lg2 = 4.0000000596e-01, /* 3ECCCCCD */
-Lg3 = 2.8571429849e-01, /* 3E924925 */
-Lg4 = 2.2222198546e-01, /* 3E638E29 */
-Lg5 = 1.8183572590e-01, /* 3E3A3325 */
-Lg6 = 1.5313838422e-01, /* 3E1CD04F */
-Lg7 = 1.4798198640e-01; /* 3E178897 */
-
-#ifdef __STDC__
-static const float zero = 0.0;
-#else
-static float zero = 0.0;
-#endif
-
-#ifdef __STDC__
- float __log2f(float x)
-#else
- float __log2f(x)
- float x;
-#endif
-{
- float hfsq,f,s,z,R,w,t1,t2,dk;
- int32_t k,ix,i,j;
-
- GET_FLOAT_WORD(ix,x);
-
- k=0;
- if (ix < 0x00800000) { /* x < 2**-126 */
- if ((ix&0x7fffffff)==0)
- return -two25/(x-x); /* log(+-0)=-inf */
- if (ix<0) return (x-x)/(x-x); /* log(-#) = NaN */
- k -= 25; x *= two25; /* subnormal number, scale up x */
- GET_FLOAT_WORD(ix,x);
- }
- if (ix >= 0x7f800000) return x+x;
- k += (ix>>23)-127;
- ix &= 0x007fffff;
- i = (ix+(0x95f64<<3))&0x800000;
- SET_FLOAT_WORD(x,ix|(i^0x3f800000)); /* normalize x or x/2 */
- k += (i>>23);
- dk = (float)k;
- f = x-(float)1.0;
- if((0x007fffff&(15+ix))<16) { /* |f| < 2**-20 */
- if(f==zero) return dk;
- R = f*f*((float)0.5-(float)0.33333333333333333*f);
- return dk-(R-f)/ln2;
- }
- s = f/((float)2.0+f);
- z = s*s;
- i = ix-(0x6147a<<3);
- w = z*z;
- j = (0x6b851<<3)-ix;
- t1= w*(Lg2+w*(Lg4+w*Lg6));
- t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
- i |= j;
- R = t2+t1;
- if(i>0) {
- hfsq=(float)0.5*f*f;
- return dk-((hfsq-(s*(hfsq+R)))-f)/ln2;
- } else {
- return dk-((s*(f-R))-f)/ln2;
- }
-}
-weak_alias (__log2f, log2f)