/* Round to nearest integer value, rounding halfway cases to even.

   flt-32 version.

   Copyright (C) 2016-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <math.h>

#include <math_private.h>

#include <libm-alias-float.h>

#include <stdint.h>

#define BIAS 0x7f

#define MANT_DIG 24

#define MAX_EXP (2 * BIAS + 1)

float

__roundevenf (float x)

{

  uint32_t ix, ux;

  GET_FLOAT_WORD (ix, x);

  ux = ix & 0x7fffffff;

  int exponent = ux >> (MANT_DIG - 1);

  if (exponent >= BIAS + MANT_DIG - 1)

    {

      /* Integer, infinity or NaN.  */

      if (exponent == MAX_EXP)

	/* Infinity or NaN; quiet signaling NaNs.  */

	return x + x;

      else

	return x;

    }

  else if (exponent >= BIAS)

    {

      /* At least 1; not necessarily an integer.  Locate the bits with

	 exponents 0 and -1 (when the unbiased exponent is 0, the bit

	 with exponent 0 is implicit, but as the bias is odd it is OK

	 to take it from the low bit of the exponent).  */

      int int_pos = (BIAS + MANT_DIG - 1) - exponent;

      int half_pos = int_pos - 1;

      uint32_t half_bit = 1U << half_pos;

      uint32_t int_bit = 1U << int_pos;

      if ((ix & (int_bit | (half_bit - 1))) != 0)

	/* Carry into the exponent works correctly.  No need to test

	   whether HALF_BIT is set.  */

	ix += half_bit;

      ix &= ~(int_bit - 1);

    }

  else if (exponent == BIAS - 1 && ux > 0x3f000000)

    /* Interval (0.5, 1).  */

    ix = (ix & 0x80000000) | 0x3f800000;

  else

    /* Rounds to 0.  */

    ix &= 0x80000000;

  SET_FLOAT_WORD (x, ix);

  return x;

}

libm_alias_float (__roundeven, roundeven)