text: /****************************************************************************
   * libc/fixedmath/lib_rint.c
   *
   *   Copyright (C) 2007, 2011, 2014 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Compilation Switches
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/types.h>
  #include <stdlib.h>
  #include <math.h>
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /****************************************************************************
   * Private Type Declarations
   ****************************************************************************/
  
  /****************************************************************************
   * Private Function Prototypes
   ****************************************************************************/
  
  /****************************************************************************
   * Public Constant Data
   ****************************************************************************/
  
  /****************************************************************************
   * Public Data
   ****************************************************************************/
  
  /****************************************************************************
   * Private Constant Data
   ****************************************************************************/
  
  /****************************************************************************
   * Private Variables
   ****************************************************************************/
  
  double rint(double x)
  {
    long   linteger;
    double fremainder;
    double ret;
  
    /* If the current rounding mode rounds toward negative
     * infinity, rint() is identical to floor().  If the current
     * rounding mode rounds toward positive infinity, rint() is
     * identical to ceil().
     */
  
  #if defined(CONFIG_FP_ROUND_POSITIVE) && CONFIG_FP_ROUNDING_POSITIVE != 0
  
    ret = ceil(x);
  
  #elif defined(CONFIG_FP_ROUND_NEGATIVE) && CONFIG_FP_ROUNDING_NEGATIVE != 0
  
    ret = floor(x);
  
  #else
  
    /* In the default rounding mode (round to nearest), rint(x) is the
     * integer nearest x with the additional stipulation that if
     * |rint(x)-x|=1/2, then rint(x) is even.
     */
  
    linteger  = (long)x;
    fremainder = x - (double)linteger;
  
    if (x < 0.0)
      {
        /* fremainder should be in range 0 .. -1 */
  
        if (fremainder == -0.5)
          {
            linteger = ((linteger + 1) & ~1);
          }
        else if (fremainder < -0.5)
          {
            linteger--;
          }
      }
    else
      {
        /* fremainder should be in range 0 .. 1 */
  
        if (fremainder == 0.5)
          {
            linteger = ((linteger + 1) & ~1);
          }
        else if (fremainder > 0.5)
          {
            linteger++;
          }
      }
  
    ret = (double)linteger;
  #endif
  
    return ret;
  }
  