GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libm/src/e_log2f.c Lines: 0 33 0.0 %
Date: 2017-11-13 Branches: 0 14 0.0 %

Line Branch Exec Source
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/* e_logf.c -- float version of e_log.c.
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 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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 */
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/*
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunPro, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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#include "math.h"
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#include "math_private.h"
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static const float
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ln2 = 0.6931471805599452862268,
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two25 =    3.355443200e+07,	/* 0x4c000000 */
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Lg1 = 6.6666668653e-01,	/* 3F2AAAAB */
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Lg2 = 4.0000000596e-01,	/* 3ECCCCCD */
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Lg3 = 2.8571429849e-01, /* 3E924925 */
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Lg4 = 2.2222198546e-01, /* 3E638E29 */
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Lg5 = 1.8183572590e-01, /* 3E3A3325 */
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Lg6 = 1.5313838422e-01, /* 3E1CD04F */
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Lg7 = 1.4798198640e-01; /* 3E178897 */
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static const float zero   =  0.0;
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float
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log2f(float x)
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{
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	float hfsq,f,s,z,R,w,t1,t2,dk;
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	int32_t k,ix,i,j;
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	GET_FLOAT_WORD(ix,x);
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	k=0;
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	if (ix < 0x00800000) {			/* x < 2**-126  */
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	    if ((ix&0x7fffffff)==0)
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		return -two25/zero;		/* log(+-0)=-inf */
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	    if (ix<0) return (x-x)/zero;	/* log(-#) = NaN */
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	    k -= 25; x *= two25; /* subnormal number, scale up x */
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	    GET_FLOAT_WORD(ix,x);
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	}
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	if (ix >= 0x7f800000) return x+x;
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	k += (ix>>23)-127;
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	ix &= 0x007fffff;
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	i = (ix+(0x95f64<<3))&0x800000;
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	SET_FLOAT_WORD(x,ix|(i^0x3f800000));	/* normalize x or x/2 */
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	k += (i>>23);
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	dk = (float)k;
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	f = x-(float)1.0;
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	if((0x007fffff&(15+ix))<16) {	/* |f| < 2**-20 */
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	    if (f==zero)
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		    return (dk);
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	    R = f*f*((float)0.5-(float)0.33333333333333333*f);
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	    return (dk-(R-f)/ln2);
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	}
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 	s = f/((float)2.0+f);
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	z = s*s;
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	i = ix-(0x6147a<<3);
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	w = z*z;
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	j = (0x6b851<<3)-ix;
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	t1= w*(Lg2+w*(Lg4+w*Lg6));
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	t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
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	i |= j;
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	R = t2+t1;
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	if(i>0) {
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	    hfsq=(float)0.5*f*f;
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	    return (dk-(hfsq-s*(hfsq+R)-f)/ln2);
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	} else
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		return (dk-((s*(f-R))-f)/ln2);
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}