sysdeps/ieee754/flt-32/s_nearbyintf.c

   1 /* s_rintf.c -- float version of s_rint.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 #include <fenv.h>
  17 #include <math.h>
  18 #include <math-barriers.h>
  19 #include <math_private.h>
  20 #include <fenv_private.h>
  21 #include <libm-alias-float.h>
  22 #include <math-use-builtins.h>
  23
  24 float
  25 __nearbyintf (float x)
  26 {
  27 #if USE_NEARBYINTF_BUILTIN
  28   return __builtin_nearbyintf (x);
  29 #else
  30   /* Use generic implementation.  */
  31   static const float
  32     TWO23[2] = {
  33                 8.3886080000e+06, /* 0x4b000000 */
  34                 -8.3886080000e+06, /* 0xcb000000 */
  35   };
  36   fenv_t env;
  37   int32_t i0, j0, sx;
  38   float w, t;
  39   GET_FLOAT_WORD (i0, x);
  40   sx = (i0 >> 31) & 1;
  41   j0 = ((i0 >> 23) & 0xff) - 0x7f;
  42   if (j0 < 23)
  43     {
  44       if (j0 < 0)
  45         {
  46           libc_feholdexceptf (&env);
  47           w = TWO23[sx] + math_opt_barrier (x);
  48           t =  w - TWO23[sx];
  49           math_force_eval (t);
  50           libc_fesetenvf (&env);
  51           GET_FLOAT_WORD (i0, t);
  52           SET_FLOAT_WORD (t, (i0 & 0x7fffffff) | (sx << 31));
  53           return t;
  54         }
  55     }
  56   else
  57     {
  58       if (__glibc_unlikely (j0 == 0x80))
  59         return x + x;           /* inf or NaN  */
  60       else
  61         return x;               /* x is integral  */
  62   }
  63   libc_feholdexceptf (&env);
  64   w = TWO23[sx] + math_opt_barrier (x);
  65   t = w - TWO23[sx];
  66   math_force_eval (t);
  67   libc_fesetenvf (&env);
  68   return t;
  69 #endif /* ! USE_NEARBYINT_BUILTIN  */
  70 }
  71 libm_alias_float (__nearbyint, nearbyint)