sysdeps/ieee754/ldbl-128/s_nearbyintl.c

   1 /* s_nearbyintl.c -- long double version of s_nearbyint.c.
   2  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 /*
  17  * nearbyintl(x)
  18  * Return x rounded to integral value according to the prevailing
  19  * rounding mode.
  20  * Method:
  21  *      Using floating addition.
  22  * Exception:
  23  *      Inexact flag raised if x not equal to rintl(x).
  24  */
  25
  26 #include <fenv.h>
  27 #include <math.h>
  28 #include <math_private.h>
  29
  30 static const long double
  31 TWO112[2]={
  32   5.19229685853482762853049632922009600E+33L, /* 0x406F000000000000, 0 */
  33  -5.19229685853482762853049632922009600E+33L  /* 0xC06F000000000000, 0 */
  34 };
  35
  36 long double __nearbyintl(long double x)
  37 {
  38         fenv_t env;
  39         int64_t i0,j0,sx;
  40         u_int64_t i1 __attribute__ ((unused));
  41         long double w,t;
  42         GET_LDOUBLE_WORDS64(i0,i1,x);
  43         sx = (((u_int64_t)i0)>>63);
  44         j0 = ((i0>>48)&0x7fff)-0x3fff;
  45         if(j0<112) {
  46             if(j0<0) {
  47                 feholdexcept (&env);
  48                 w = TWO112[sx]+x;
  49                 t = w-TWO112[sx];
  50                 math_force_eval (t);
  51                 fesetenv (&env);
  52                 GET_LDOUBLE_MSW64(i0,t);
  53                 SET_LDOUBLE_MSW64(t,(i0&0x7fffffffffffffffLL)|(sx<<63));
  54                 return t;
  55             }
  56         } else {
  57             if(j0==0x4000) return x+x;  /* inf or NaN */
  58             else return x;              /* x is integral */
  59         }
  60         feholdexcept (&env);
  61         w = TWO112[sx]+x;
  62         t = w-TWO112[sx];
  63         math_force_eval (t);
  64         fesetenv (&env);
  65         return t;
  66 }
  67 weak_alias (__nearbyintl, nearbyintl)