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

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• Hash : b72938c8
  Author :
  Date : 2015-04-20T12:22:44
  

  Windows: Always set the system timer resolution to 1ms by default.
  
  An existing hint lets apps that don't need the timer resolution changed avoid
  this, to save battery, etc, but this fixes several problems in timing, audio
  callbacks not firing fast enough, etc.
  
  Fixes Bugzilla #2944.
  

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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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