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/*
* Copyright (c) 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_MISC_RANDOM_H
#define ARM_COMPUTE_MISC_RANDOM_H
#include "arm_compute/core/Error.h"
#include <random>
#include <type_traits>
namespace arm_compute
{
namespace utils
{
namespace random
{
/** Uniform distribution within a given number of sub-ranges
*
* @tparam T Distribution primitive type
*/
template <typename T>
class RangedUniformDistribution
{
public:
using DT = typename std::conditional<std::is_integral<T>::value,
std::uniform_int_distribution<T>,
std::uniform_real_distribution<float>>::type;
using result_type = T;
using range_pair = std::pair<result_type, result_type>;
public:
/** Constructor
*
* @param[in] low lowest value in the range (inclusive)
* @param[in] high highest value in the range (inclusive for uniform_int_distribution, exclusive for uniform_real_distribution)
* @param[in] exclude_ranges Ranges to exclude from the generator
*/
RangedUniformDistribution(result_type low, result_type high, const std::vector<range_pair> &exclude_ranges)
: _distributions(), _selector()
{
result_type clow = low;
for(const auto &erange : exclude_ranges)
{
result_type epsilon = std::is_integral<result_type>::value ? 1 : static_cast<result_type>(std::numeric_limits<float>::epsilon());
ARM_COMPUTE_ERROR_ON(clow > erange.first || clow >= erange.second);
_distributions.emplace_back(DT(clow, erange.first - epsilon));
clow = erange.second + epsilon;
}
ARM_COMPUTE_ERROR_ON(clow > high);
_distributions.emplace_back(DT(clow, high));
_selector = std::uniform_int_distribution<uint32_t>(0, _distributions.size() - 1);
}
/** Generate random number
*
* @tparam URNG Random number generator object type
*
* @param[in] g A uniform random number generator object, used as the source of randomness.
*
* @return A new random number.
*/
template <class URNG>
result_type operator()(URNG &g)
{
unsigned int rand_select = _selector(g);
return _distributions[rand_select](g);
}
private:
std::vector<DT> _distributions;
std::uniform_int_distribution<uint32_t> _selector;
};
} // namespace random
} // namespace utils
} // namespace arm_compute
#endif /* ARM_COMPUTE_MISC_RANDOM_H */
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