sysdeps/ieee754/ldbl-128/s_nearbyintl.c

   1 /* s_nearbyintl.c -- long double version of s_nearbyint.c.
   2  */
   3
   4 /*
   5  * ====================================================
   6  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   7  *
   8  * Developed at SunPro, a Sun Microsystems, Inc. business.
   9  * Permission to use, copy, modify, and distribute this
  10  * software is freely granted, provided that this notice
  11  * is preserved.
  12  * ====================================================
  13  */
  14
  15 /*
  16  * nearbyintl(x)
  17  * Return x rounded to integral value according to the prevailing
  18  * rounding mode.
  19  * Method:
  20  *      Using floating addition.
  21  * Exception:
  22  *      Inexact flag raised if x not equal to rintl(x).
  23  */
  24
  25 #include <fenv.h>
  26 #include <math.h>
  27 #include <math-barriers.h>
  28 #include <math_private.h>
  29 #include <libm-alias-ldouble.h>
  30 #include <math-use-builtins.h>
  31
  32 _Float128
  33 __nearbyintl (_Float128 x)
  34 {
  35 #if USE_NEARBYINTL_BUILTIN
  36   return __builtin_nearbyintl (x);
  37 #else
  38   /* Use generic implementation.  */
  39   static const _Float128
  40     TWO112[2] = {
  41                  L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
  42                  L(-5.19229685853482762853049632922009600E+33)  /* 0xC06F000000000000, 0 */
  43   };
  44   fenv_t env;
  45   int64_t i0, j0, sx;
  46   uint64_t i1 __attribute__ ((unused));
  47   _Float128 w, t;
  48   GET_LDOUBLE_WORDS64 (i0, i1, x);
  49   sx = (((uint64_t) i0) >> 63);
  50   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  51   if (j0 < 112)
  52     {
  53       if (j0 < 0)
  54         {
  55           feholdexcept (&env);
  56           w = TWO112[sx] + math_opt_barrier (x);
  57           t = w - TWO112[sx];
  58           math_force_eval (t);
  59           fesetenv (&env);
  60           GET_LDOUBLE_MSW64 (i0, t);
  61           SET_LDOUBLE_MSW64 (t, (i0 & 0x7fffffffffffffffLL) | (sx << 63));
  62           return t;
  63         }
  64     }
  65   else
  66     {
  67       if (j0 == 0x4000)
  68         return x + x;           /* inf or NaN  */
  69       else
  70         return x;               /* x is integral  */
  71     }
  72   feholdexcept (&env);
  73   w = TWO112[sx] + math_opt_barrier (x);
  74   t = w - TWO112[sx];
  75   math_force_eval (t);
  76   fesetenv (&env);
  77   return t;
  78 #endif /* ! USE_NEARBYINTL_BUILTIN  */
  79 }
  80 libm_alias_ldouble (__nearbyint, nearbyint)