sysdeps/ieee754/flt-32/s_nearbyintf.c

   1 /* s_rintf.c -- float version of s_rint.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  */
   4 /* Adapted for use as nearbyint by Ulrich Drepper <drepper@cygnus.com>.  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17
  18 #include <fenv.h>
  19 #include <math.h>
  20 #include <math_private.h>
  21
  22 static const float
  23 TWO23[2]={
  24   8.3886080000e+06, /* 0x4b000000 */
  25  -8.3886080000e+06, /* 0xcb000000 */
  26 };
  27
  28 float
  29 __nearbyintf(float x)
  30 {
  31         fenv_t env;
  32         int32_t i0,j0,sx;
  33         float w,t;
  34         GET_FLOAT_WORD(i0,x);
  35         sx = (i0>>31)&1;
  36         j0 = ((i0>>23)&0xff)-0x7f;
  37         if(j0<23) {
  38             if(j0<0) {
  39                 libc_feholdexceptf (&env);
  40                 w = TWO23[sx]+x;
  41                 t =  w-TWO23[sx];
  42                 math_force_eval (t);
  43                 libc_fesetenvf (&env);
  44                 GET_FLOAT_WORD(i0,t);
  45                 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
  46                 return t;
  47             }
  48         } else {
  49             if(__builtin_expect(j0==0x80, 0)) return x+x;       /* inf or NaN */
  50             else return x;              /* x is integral */
  51         }
  52         libc_feholdexceptf (&env);
  53         w = TWO23[sx]+x;
  54         t = w-TWO23[sx];
  55         math_force_eval (t);
  56         libc_fesetenvf (&env);
  57         return t;
  58 }
  59 weak_alias (__nearbyintf, nearbyintf)