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)