kc3-lang/SDL/src/libm/s_scalbn.c

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• Hash : 1e49b1ed
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  Date : 2013-08-21T09:47:10
  

  OCD fixes: Adds a space after /* (glory to regular expressions!)
  

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• src/libm/s_scalbn.c

• /* @(#)s_scalbn.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.
   * ====================================================
   */
  
  #if defined(LIBM_SCCS) && !defined(lint)
  static const char rcsid[] =
      "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
  #endif
  
  /*
   * scalbn (double x, int n)
   * scalbn(x,n) returns x* 2**n  computed by  exponent
   * manipulation rather than by actually performing an
   * exponentiation or a multiplication.
   */
  
  #include "math_libm.h"
  #include "math_private.h"
  
  libm_hidden_proto(copysign)
  #ifdef __STDC__
       static const double
  #else
       static double
  #endif
         two54 = 1.80143985094819840000e+16,      /* 0x43500000, 0x00000000 */
           twom54 = 5.55111512312578270212e-17,   /* 0x3C900000, 0x00000000 */
           huge_val = 1.0e+300, tiny = 1.0e-300;
  
  libm_hidden_proto(scalbn)
  #ifdef __STDC__
       double scalbn(double x, int n)
  #else
       double scalbn(x, n)
       double x;
       int n;
  #endif
  {
      int32_t k, hx, lx;
      EXTRACT_WORDS(hx, lx, x);
      k = (hx & 0x7ff00000) >> 20;        /* extract exponent */
      if (k == 0) {               /* 0 or subnormal x */
          if ((lx | (hx & 0x7fffffff)) == 0)
              return x;           /* +-0 */
          x *= two54;
          GET_HIGH_WORD(hx, x);
          k = ((hx & 0x7ff00000) >> 20) - 54;
          if (n < -50000)
              return tiny * x;    /* underflow */
      }
      if (k == 0x7ff)
          return x + x;           /* NaN or Inf */
      k = k + n;
      if (k > 0x7fe)
          return huge_val * copysign(huge_val, x);        /* overflow  */
      if (k > 0) {                /* normal result */
          SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
          return x;
      }
      if (k <= -54) {
          if (n > 50000)          /* in case integer overflow in n+k */
              return huge_val * copysign(huge_val, x);    /* overflow */
          else
              return tiny * copysign(tiny, x);    /* underflow */
      }
      k += 54;                    /* subnormal result */
      SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
      return x * twom54;
  }
  
  libm_hidden_def(scalbn)
  

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