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Viewing changes to android/bionic/libm/src/e_acosf.c

  • Committer: Package Import Robot
  • Author(s): Dmitrijs Ledkovs
  • Date: 2013-07-05 10:12:24 UTC
  • Revision ID: package-import@ubuntu.com-20130705101224-6qo3e8jbz8p31aa1
Tags: upstream-0.20130705.1
Import upstream version 0.20130705.1

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android/bionic/libm/src/e_acosf.c
 
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/* e_acosf.c -- float version of e_acos.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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#ifndef lint
 
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static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_acosf.c,v 1.7 2002/05/28 17:03:12 alfred Exp $";
 
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#endif
 
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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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one =  1.0000000000e+00, /* 0x3F800000 */
 
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pi =  3.1415925026e+00, /* 0x40490fda */
 
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pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
 
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pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
 
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pS0 =  1.6666667163e-01, /* 0x3e2aaaab */
 
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pS1 = -3.2556581497e-01, /* 0xbea6b090 */
 
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pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
 
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pS3 = -4.0055535734e-02, /* 0xbd241146 */
 
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pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
 
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pS5 =  3.4793309169e-05, /* 0x3811ef08 */
 
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qS1 = -2.4033949375e+00, /* 0xc019d139 */
 
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qS2 =  2.0209457874e+00, /* 0x4001572d */
 
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qS3 = -6.8828397989e-01, /* 0xbf303361 */
 
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qS4 =  7.7038154006e-02; /* 0x3d9dc62e */
 
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float
 
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__ieee754_acosf(float x)
 
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{
 
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        float z,p,q,r,w,s,c,df;
 
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        int32_t hx,ix;
 
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        GET_FLOAT_WORD(hx,x);
 
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        ix = hx&0x7fffffff;
 
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        if(ix==0x3f800000) {            /* |x|==1 */
 
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            if(hx>0) return 0.0;        /* acos(1) = 0  */
 
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            else return pi+(float)2.0*pio2_lo;  /* acos(-1)= pi */
 
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        } else if(ix>0x3f800000) {      /* |x| >= 1 */
 
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            return (x-x)/(x-x);         /* acos(|x|>1) is NaN */
 
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        }
 
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        if(ix<0x3f000000) {     /* |x| < 0.5 */
 
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            if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
 
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            z = x*x;
 
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            p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
 
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            q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
 
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            r = p/q;
 
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            return pio2_hi - (x - (pio2_lo-x*r));
 
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        } else  if (hx<0) {             /* x < -0.5 */
 
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            z = (one+x)*(float)0.5;
 
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            p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
 
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            q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
 
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            s = __ieee754_sqrtf(z);
 
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            r = p/q;
 
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            w = r*s-pio2_lo;
 
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            return pi - (float)2.0*(s+w);
 
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        } else {                        /* x > 0.5 */
 
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            int32_t idf;
 
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            z = (one-x)*(float)0.5;
 
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            s = __ieee754_sqrtf(z);
 
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            df = s;
 
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            GET_FLOAT_WORD(idf,df);
 
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            SET_FLOAT_WORD(df,idf&0xfffff000);
 
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            c  = (z-df*df)/(s+df);
 
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            p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
 
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            q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
 
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            r = p/q;
 
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            w = r*s+c;
 
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            return (float)2.0*(df+w);
 
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        }
 
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}