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/************************************************************
* lib_rint.c
*
* Copyright (C) 2007 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 Gregory Nutt 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>
/************************************************************
* Definitions
************************************************************/
/************************************************************
* Private Type Declarations
************************************************************/
/************************************************************
* Private Function Prototypes
************************************************************/
/**********************************************************
* Global Constant Data
**********************************************************/
/************************************************************
* Global Variables
************************************************************/
/**********************************************************
* Private Constant Data
**********************************************************/
/************************************************************
* Private Variables
************************************************************/
double_t rint(double_t x)
{
double_t 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.
*/
long dwinteger = (long)x;
double_t fremainder = x - (double_t)dwinteger;
if (x < 0.0)
{
/* fremainder should be in range 0 .. -1 */
if (fremainder == -0.5)
{
dwinteger = ((dwinteger+1)&~1);
}
else if (fremainder < -0.5)
{
dwinteger--;
}
}
else
{
/* fremainder should be in range 0 .. 1 */
if (fremainder == 0.5)
{
dwinteger = ((dwinteger+1)&~1);
}
else if (fremainder > 0.5)
{
dwinteger++;
}
}
ret = (double_t)dwinteger;
#endif
return ret;
}
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