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-barriers.h>
  21 #include <math_private.h>
  22 #include <fenv_private.h>
  23 #include <libm-alias-float.h>
  24 #include <math-use-builtins.h>
  25
  26 float
  27 __nearbyintf(float x)
  28 {
  29 #if USE_NEARBYINTF_BUILTIN
  30   return __builtin_nearbyintf (x);
  31 #else
  32   /* Use generic implementation.  */
  33   static const float
  34     TWO23[2] = {
  35                 8.3886080000e+06, /* 0x4b000000 */
  36                 -8.3886080000e+06, /* 0xcb000000 */
  37   };
  38         fenv_t env;
  39         int32_t i0,j0,sx;
  40         float w,t;
  41         GET_FLOAT_WORD(i0,x);
  42         sx = (i0>>31)&1;
  43         j0 = ((i0>>23)&0xff)-0x7f;
  44         if(j0<23) {
  45             if(j0<0) {
  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         } else {
  56             if(__builtin_expect(j0==0x80, 0)) return x+x;       /* inf or NaN */
  57             else return x;              /* x is integral */
  58         }
  59         libc_feholdexceptf (&env);
  60         w = TWO23[sx] + math_opt_barrier (x);
  61         t = w-TWO23[sx];
  62         math_force_eval (t);
  63         libc_fesetenvf (&env);
  64         return t;
  65 #endif /* ! USE_NEARBYINT_BUILTIN  */
  66 }
  67 libm_alias_float (__nearbyint, nearbyint)