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[/] [openrisc/] [trunk/] [gnu-old/] [gcc-4.2.2/] [gcc/] [testsuite/] [gcc.c-torture/] [execute/] [cbrt.c] - Blame information for rev 816

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Line No. Rev Author Line
1 149 jeremybenn
/*
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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 __vax__
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static const unsigned long
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        B1 = 715094163, /* B1 = (682-0.03306235651)*2**20 */
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        B2 = 696219795; /* B2 = (664-0.03306235651)*2**20 */
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static const double
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        C =  5.42857142857142815906e-01, /* 19/35     = 0x3FE15F15, 0xF15F15F1 */
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        D = -7.05306122448979611050e-01, /* -864/1225 = 0xBFE691DE, 0x2532C834 */
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        E =  1.41428571428571436819e+00, /* 99/70     = 0x3FF6A0EA, 0x0EA0EA0F */
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        F =  1.60714285714285720630e+00, /* 45/28     = 0x3FF9B6DB, 0x6DB6DB6E */
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        G =  3.57142857142857150787e-01; /* 5/14      = 0x3FD6DB6D, 0xB6DB6DB7 */
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double
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cbrtl (double x)
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{
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  long hx;
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  double r,s,w;
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  double lt;
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  unsigned sign;
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  typedef unsigned unsigned32 __attribute__((mode(SI)));
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  union {
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    double t;
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    unsigned32 pt[2];
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  } ut, ux;
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  int n0;
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  ut.t = 1.0;
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  n0 = (ut.pt[0] == 0);
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  ut.t = 0.0;
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  ux.t = x;
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  hx = ux.pt[n0];                       /* high word of x */
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  sign=hx&0x80000000;                   /* sign= sign(x) */
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  hx  ^=sign;
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  if(hx>=0x7ff00000) return(x+x);       /* cbrt(NaN,INF) is itself */
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  if((hx| ux.pt[1-n0])==0)
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    return(ux.t);                       /* cbrt(0) is itself */
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  ux.pt[n0] = hx;
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  /* rough cbrt to 5 bits */
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  if(hx<0x00100000)                     /* subnormal number */
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    {ut.pt[n0]=0x43500000;              /* set t= 2**54 */
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     ut.t*=x; ut.pt[n0]=ut.pt[n0]/3+B2;
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   }
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  else
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    ut.pt[n0]=hx/3+B1;
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  /* new cbrt to 23 bits, may be implemented in single precision */
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  r=ut.t*ut.t/ux.t;
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  s=C+r*ut.t;
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  ut.t*=G+F/(s+E+D/s);
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  /* chopped to 20 bits and make it larger than cbrt(x) */
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  ut.pt[1-n0]=0; ut.pt[n0]+=0x00000001;
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  /* one step newton iteration to 53 bits with error less than 0.667 ulps */
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  s=ut.t*ut.t;                          /* t*t is exact */
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  r=ux.t/s;
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  w=ut.t+ut.t;
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  r=(r-ut.t)/(w+r);                     /* r-s is exact */
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  ut.t=ut.t+ut.t*r;
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  /* restore the sign bit */
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  ut.pt[n0] |= sign;
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  lt = ut.t;
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  lt -= (lt - (x/(lt*lt))) * 0.333333333333333333333;
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  return lt;
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}
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main ()
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{
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  if ((int) (cbrtl (27.0) + 0.5) != 3)
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    abort ();
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  exit (0);
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}
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#else
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main () { exit (0); }
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#endif

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