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