8d1eb0a195
Currently the lookahead is disabled by default because of the time to compute and RAM usage. However it does appear to work reasonably well in testing. Further effort is required to lower RAM usage after initial computation, and explore trade-off for cheaper time to compute. Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
/*
|
|
* 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_ */
|