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/*
* Copyright (c) 2018-2019 Arm Limited.
*
* SPDX-License-Identifier: MIT
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifndef ARM_COMPUTE_UTILS_ROUNDING_H
#define ARM_COMPUTE_UTILS_ROUNDING_H
#include "arm_compute/core/Error.h"
#include "arm_compute/core/utils/misc/Requires.h"
#include "arm_compute/core/utils/misc/Traits.h"
#include "support/ToolchainSupport.h"
#include <cmath>
namespace arm_compute
{
namespace utils
{
namespace rounding
{
/** Rounding mode */
enum class RoundingMode
{
TO_ZERO, /**< Round towards zero */
AWAY_FROM_ZERO, /**< Round away from zero */
HALF_TO_ZERO, /**< Round half towards from zero */
HALF_AWAY_FROM_ZERO, /**< Round half away from zero */
HALF_UP, /**< Round half towards positive infinity */
HALF_DOWN, /**< Round half towards negative infinity */
HALF_EVEN /**< Round half towards nearest even */
};
/** Round floating-point value with round to zero
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_to_zero(T value)
{
T res = std::floor(std::fabs(value));
return (value < 0.f) ? -res : res;
}
/** Round floating-point value with round away from zero
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_away_from_zero(T value)
{
T res = std::ceil(std::fabs(value));
return (value < 0.f) ? -res : res;
}
/** Round floating-point value with half value rounding towards zero.
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_half_to_zero(T value)
{
T res = T(std::ceil(std::fabs(value) - 0.5f));
return (value < 0.f) ? -res : res;
}
/** Round floating-point value with half value rounding away from zero.
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_half_away_from_zero(T value)
{
T res = T(std::floor(std::fabs(value) + 0.5f));
return (value < 0.f) ? -res : res;
}
/** Round floating-point value with half value rounding to positive infinity.
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_half_up(T value)
{
return std::floor(value + 0.5f);
}
/** Round floating-point value with half value rounding to negative infinity.
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_half_down(T value)
{
return std::ceil(value - 0.5f);
}
/** Round floating-point value with half value rounding to nearest even.
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
* @param[in] epsilon precision.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round_half_even(T value, T epsilon = std::numeric_limits<T>::epsilon())
{
T positive_value = std::abs(value);
T ipart = 0;
std::modf(positive_value, &ipart);
// If 'value' is exactly halfway between two integers
if(std::abs(positive_value - (ipart + 0.5f)) < epsilon)
{
// If 'ipart' is even then return 'ipart'
if(std::fmod(ipart, 2.f) < epsilon)
{
return support::cpp11::copysign(ipart, value);
}
// Else return the nearest even integer
return support::cpp11::copysign(std::ceil(ipart + 0.5f), value);
}
// Otherwise use the usual round to closest
return support::cpp11::copysign(support::cpp11::round(positive_value), value);
}
/** Round floating-point value given a rounding mode
*
* @tparam T Parameter type. Should be of floating point type.
*
* @param[in] value floating-point value to be rounded.
* @param[in] rounding_mode Rounding mode to use.
*
* @return Floating-point value of rounded @p value.
*/
template <typename T, REQUIRES_TA(traits::is_floating_point<T>::value)>
inline T round(T value, RoundingMode rounding_mode)
{
switch(rounding_mode)
{
case RoundingMode::TO_ZERO:
return round_to_zero(value);
case RoundingMode::AWAY_FROM_ZERO:
return round_away_from_zero(value);
case RoundingMode::HALF_TO_ZERO:
return round_half_to_zero(value);
case RoundingMode::HALF_AWAY_FROM_ZERO:
return round_half_away_from_zero(value);
case RoundingMode::HALF_UP:
return round_half_up(value);
case RoundingMode::HALF_DOWN:
return round_half_down(value);
case RoundingMode::HALF_EVEN:
return round_half_even(value);
default:
ARM_COMPUTE_ERROR("Unsupported rounding mode!");
}
}
} // namespace rounding
} // namespace utils
} // namespace arm_compute
#endif /*ARM_COMPUTE_UTILS_ROUNDING_H */
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