glibc/sysdeps/ieee754/ldbl-128/s_nearbyintl.c

/* s_nearbyintl.c -- long double version of s_nearbyint.c.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*
 * nearbyintl(x)
 * Return x rounded to integral value according to the prevailing
 * rounding mode.
 * Method:
 *	Using floating addition.
 * Exception:
 *	Inexact flag raised if x not equal to rintl(x).
 */

#include <fenv.h>
#include <math.h>
#include <math-barriers.h>
#include <math_private.h>
#include <libm-alias-ldouble.h>
#include <math-use-builtins.h>

_Float128
__nearbyintl (_Float128 x)
{
#if USE_NEARBYINTL_BUILTIN
  return __builtin_nearbyintl (x);
#else
  /* Use generic implementation.  */
  static const _Float128
    TWO112[2] = {
		 L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
		 L(-5.19229685853482762853049632922009600E+33)  /* 0xC06F000000000000, 0 */
  };
  fenv_t env;
  int64_t i0, j0, sx;
  uint64_t i1 __attribute__ ((unused));
  _Float128 w, t;
  GET_LDOUBLE_WORDS64 (i0, i1, x);
  sx = (((uint64_t) i0) >> 63);
  j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  if (j0 < 112)
    {
      if (j0 < 0)
	{
	  feholdexcept (&env);
	  w = TWO112[sx] + math_opt_barrier (x);
	  t = w - TWO112[sx];
	  math_force_eval (t);
	  fesetenv (&env);
	  GET_LDOUBLE_MSW64 (i0, t);
	  SET_LDOUBLE_MSW64 (t, (i0 & 0x7fffffffffffffffLL) | (sx << 63));
	  return t;
	}
    }
  else
    {
      if (j0 == 0x4000)
	return x + x;		/* inf or NaN  */
      else
	return x;		/* x is integral  */
    }
  feholdexcept (&env);
  w = TWO112[sx] + math_opt_barrier (x);
  t = w - TWO112[sx];
  math_force_eval (t);
  fesetenv (&env);
  return t;
#endif /* ! USE_NEARBYINTL_BUILTIN  */
}
libm_alias_ldouble (__nearbyint, nearbyint)