libquadmath/math/nearbyintq.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  * nearbyintq(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 rintq(x).
  24  */
  25
  26 #include "quadmath-imp.h"
  27
  28 static const __float128
  29 TWO112[2]={
  30   5.19229685853482762853049632922009600E+33Q, /* 0x406F000000000000, 0 */
  31  -5.19229685853482762853049632922009600E+33Q  /* 0xC06F000000000000, 0 */
  32 };
  33
  34 __float128 nearbyintq(__float128 x)
  35 {
  36         fenv_t env;
  37         int64_t i0,j0,sx;
  38         uint64_t i1 __attribute__ ((unused));
  39         __float128 w,t;
  40         GET_FLT128_WORDS64(i0,i1,x);
  41         sx = (((uint64_t)i0)>>63);
  42         j0 = ((i0>>48)&0x7fff)-0x3fff;
  43         if(j0<112) {
  44             if(j0<0) {
  45                 feholdexcept (&env);
  46                 w = TWO112[sx] + math_opt_barrier (x);
  47                 t = w-TWO112[sx];
  48                 math_force_eval (t);
  49                 fesetenv (&env);
  50                 GET_FLT128_MSW64(i0,t);
  51                 SET_FLT128_MSW64(t,(i0&0x7fffffffffffffffLL)|(sx<<63));
  52                 return t;
  53             }
  54         } else {
  55             if(j0==0x4000) return x+x;  /* inf or NaN */
  56             else return x;              /* x is integral */
  57         }
  58         feholdexcept (&env);
  59         w = TWO112[sx] + math_opt_barrier (x);
  60         t = w-TWO112[sx];
  61         math_force_eval (t);
  62         fesetenv (&env);
  63         return t;
  64 }