/*
* 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>
/** Truncate fractional part (round towards zero)
*
* Truncate the fractional part of IEEE 754 single
* precision floating point number by zeroing fraction
* bits, effectively rounding the number towards zero
* to the nearest whole number.
*
* If the argument is infinity or NaN, an exception
* should be indicated. This is not implemented yet.
*
* @param val Floating point number.
*
* @return Number rounded towards zero.
*
*/
float truncf(float val)
{
const int exp_bias = FLT_MAX_EXP - 1;
const int mant_bits = FLT_MANT_DIG - 1;
const uint32_t mant_mask = (UINT32_C(1) << mant_bits) - 1;
union {
float f;
uint32_t i;
} u = { .f = fabsf(val) };
int exp = (u.i >> mant_bits) - exp_bias;
/* If value is less than one, return zero with appropriate sign. */
if (exp < 0)
return copysignf(0.0f, val);
if (exp >= mant_bits)
return val;
/* Truncate irrelevant fraction bits */
u.i &= ~(mant_mask >> exp);
return copysignf(u.f, val);
}
/** Truncate fractional part (round towards zero)
*
* Truncate the fractional part of IEEE 754 double
* precision floating point number by zeroing fraction
* bits, effectively rounding the number towards zero
* to the nearest whole number.
*
* If the argument is infinity or NaN, an exception
* should be indicated. This is not implemented yet.
*
* @param val Floating point number.
*
* @return Number rounded towards zero.
*
*/
double trunc(double val)
{
const int exp_bias = DBL_MAX_EXP - 1;
const int mant_bits = DBL_MANT_DIG - 1;
const uint64_t mant_mask = (UINT64_C(1) << mant_bits) - 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 one, return zero with appropriate sign. */
if (exp < 0)
return copysign(0.0, val);
if (exp >= mant_bits)
return val;
/* Truncate irrelevant fraction bits */
u.i &= ~(mant_mask >> exp);
return copysign(u.f, val);
}
/** @}
*/