125 lines
3.9 KiB
C
125 lines
3.9 KiB
C
/****************************************************************************
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* libs/libc/math/lib_rintl.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdlib.h>
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#include <math.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Type Declarations
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Public Constant Data
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****************************************************************************/
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/****************************************************************************
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* Public Data
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****************************************************************************/
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/****************************************************************************
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* Private Constant Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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long double rintl(long double x)
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{
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int64_t llinteger;
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long double fremainder;
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long double ret;
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/* If the current rounding mode rounds toward negative
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* infinity, rint() is identical to floor(). If the current
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* rounding mode rounds toward positive infinity, rint() is
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* identical to ceil().
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*/
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#if defined(CONFIG_FP_ROUND_POSITIVE) && CONFIG_FP_ROUNDING_POSITIVE != 0
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ret = ceil(x);
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#elif defined(CONFIG_FP_ROUND_NEGATIVE) && CONFIG_FP_ROUNDING_NEGATIVE != 0
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ret = floor(x);
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#else
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/* In the default rounding mode (round to nearest), rint(x) is the
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* integer nearest x with the additional stipulation that if
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* |rint(x)-x|=1/2, then rint(x) is even.
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*/
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llinteger = (int64_t)x;
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fremainder = x - (long double)llinteger;
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if (x < 0.0)
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{
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/* fremainder should be in range 0 .. -1 */
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if (fremainder == -0.5)
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{
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llinteger = ((llinteger + 1) & ~1);
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}
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else if (fremainder < -0.5)
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{
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llinteger--;
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}
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}
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else
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{
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/* fremainder should be in range 0 .. 1 */
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if (fremainder == 0.5)
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{
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llinteger = ((llinteger + 1) & ~1);
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}
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else if (fremainder > 0.5)
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{
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llinteger++;
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}
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}
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ret = (long double)llinteger;
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#endif
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return ret;
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}
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