/*
* Copyright (c) 2015 Jiri Svoboda
* Copyright (c) 2014 Martin Decky
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/** @addtogroup libmath
* @{
*/
/** @file
*/
#include <math.h>
#include <float.h>
#include <stdint.h>
/**
* Rounds its argument to the nearest integer value in floating-point format,
* rounding halfway cases away from zero, regardless of the current rounding
* direction.
*/
float roundf(float val)
{
const int exp_bias = FLT_MAX_EXP - 1;
const int mant_bits = FLT_MANT_DIG - 1;
union {
float f;
uint32_t i;
} u = { .f = fabsf(val) };
int exp = (u.i >> mant_bits) - exp_bias;
/* If value is less than 0.5, return zero with appropriate sign. */
if (exp < -1)
return copysignf(0.0f, val);
/* If exponent is exactly mant_bits, adding 0.5 could change the result. */
if (exp >= mant_bits)
return val;
/* Use trunc with adjusted value to do the rounding. */
return copysignf(truncf(u.f + 0.5), val);
}
/**
* Rounds its argument to the nearest integer value in floating-point format,
* rounding halfway cases away from zero, regardless of the current rounding
* direction.
*/
double round(double val)
{
const int exp_bias = DBL_MAX_EXP - 1;
const int mant_bits = DBL_MANT_DIG - 1;
union {
double f;
uint64_t i;
} u = { .f = fabs(val) };
int exp = ((int)(u.i >> mant_bits)) - exp_bias;
/* If value is less than 0.5, return zero with appropriate sign. */
if (exp < -1)
return copysign(0.0, val);
/* If exponent is exactly mant_bits, adding 0.5 could change the result. */
if (exp >= mant_bits)
return val;
/* Use trunc with adjusted value to do the rounding. */
return copysign(trunc(u.f + 0.5), val);
}
/** @}
*/