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/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2021 Symbiflow Authors
*
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#ifndef SAMPLER_H_
#define SAMPLER_H_
#include <cstdint>
#include <functional>
#include <stdexcept>
#include <vector>
#include "nextpnr_namespaces.h"
NEXTPNR_NAMESPACE_BEGIN
// Given a set of coordinates, generates random samples that are geometric
// distributed.
struct Sampler
{
void divide_samples(size_t target_sample_count, const std::vector<std::pair<int32_t, int32_t>> &samples);
size_t number_of_regions() const { return splits.size() - 1; }
size_t get_sample_from_region(size_t region, std::function<int32_t()> rng) const
{
if (region >= (splits.size() - 1)) {
throw std::runtime_error("region out of range");
}
size_t split_begin = splits[region];
size_t split_end = splits[region + 1];
if (split_begin == split_end) {
throw std::runtime_error("Splits should never be empty!");
}
// Pick a random element from that region.
return indicies[split_begin + (rng() % (split_end - split_begin))];
}
size_t get_sample(std::function<int32_t()> rng) const
{
size_t region = rng() % number_of_regions();
return get_sample_from_region(region, rng);
}
std::vector<size_t> indicies;
std::vector<size_t> splits;
};
NEXTPNR_NAMESPACE_END
#endif /* SAMPLER_H_ */
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