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 #ifdef __STDC__
  31 static const long double
  32 #else
  33 static long double
  34 #endif
  35 TWO112[2]={
  36   5.19229685853482762853049632922009600E+33L, /* 0x406F000000000000, 0 */
  37  -5.19229685853482762853049632922009600E+33L  /* 0xC06F000000000000, 0 */
  38 };
  39
  40 #ifdef __STDC__
  41         long double __nearbyintl(long double x)
  42 #else
  43         long double __nearbyintl(x)
  44         long double x;
  45 #endif
  46 {
  47         fenv_t env;
  48         int64_t i0,j0,sx;
  49         u_int64_t i,i1;
  50         long double w,t;
  51         GET_LDOUBLE_WORDS64(i0,i1,x);
  52         sx = (((u_int64_t)i0)>>63);
  53         j0 = ((i0>>48)&0x7fff)-0x3fff;
  54         if(j0<48) {
  55             if(j0<0) {
  56                 if(((i0&0x7fffffffffffffffLL)|i1)==0) return x;
  57                 i1 |= (i0&0x0000ffffffffffffLL);
  58                 i0 &= 0xffffe00000000000ULL;
  59                 i0 |= ((i1|-i1)>>16)&0x0000800000000000LL;
  60                 SET_LDOUBLE_MSW64(x,i0);
  61                 feholdexcept (&env);
  62                 w = TWO112[sx]+x;
  63                 t = w-TWO112[sx];
  64                 fesetenv (&env);
  65                 GET_LDOUBLE_MSW64(i0,t);
  66                 SET_LDOUBLE_MSW64(t,(i0&0x7fffffffffffffffLL)|(sx<<63));
  67                 return t;
  68             } else {
  69                 i = (0x0000ffffffffffffLL)>>j0;
  70                 if(((i0&i)|i1)==0) return x; /* x is integral */
  71                 i>>=1;
  72                 if(((i0&i)|i1)!=0) {
  73                     if(j0==47) i1 = 0x4000000000000000ULL; else
  74                     i0 = (i0&(~i))|((0x0000200000000000LL)>>j0);
  75                 }
  76             }
  77         } else if (j0>111) {
  78             if(j0==0x4000) return x+x;  /* inf or NaN */
  79             else return x;              /* x is integral */
  80         } else {
  81             i = -1ULL>>(j0-48);
  82             if((i1&i)==0) return x;     /* x is integral */
  83             i>>=1;
  84             if((i1&i)!=0) i1 = (i1&(~i))|((0x4000000000000000LL)>>(j0-48));
  85         }
  86         SET_LDOUBLE_WORDS64(x,i0,i1);
  87         feholdexcept (&env);
  88         w = TWO112[sx]+x;
  89         t = w-TWO112[sx];
  90         fesetenv (&env);
  91         return t;
  92 }
  93 weak_alias (__nearbyintl, nearbyintl)