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- // a sorting example that uses the worst-case for conventional MSD radix sorts.
- //
- // Copyright Steven Ross 2009-2014.
- //
- // Distributed under the Boost Software License, Version 1.0.
- // (See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- // See http://www.boost.org/libs/sort for library home page.
- #include <boost/sort/spreadsort/spreadsort.hpp>
- #include <time.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <algorithm>
- #include <vector>
- #include <string>
- #include <fstream>
- #include <sstream>
- #include <iostream>
- using namespace boost::sort::spreadsort;
- using namespace std;
- #define DATA_TYPE boost::uint64_t
- #define ALR_THRESHOLD 3
- const unsigned max_count = ALR_THRESHOLD - 1;
- const unsigned bit_shift = detail::rough_log_2_size(max_count) -
- detail::int_log_mean_bin_size;
- const unsigned radix_threshold = detail::rough_log_2_size(max_count) + 1;
- //Increase this size if too fast to test accurately
- const unsigned top_splits = 12;
- const DATA_TYPE typed_one = 1;
- void
- fill_vector(vector<DATA_TYPE> & input, const DATA_TYPE base_value,
- unsigned remaining_bits)
- {
- if (remaining_bits >= radix_threshold) {
- input.push_back((base_value << remaining_bits) +
- ((typed_one << remaining_bits) - 1));
- fill_vector(input, base_value << bit_shift, remaining_bits - bit_shift);
- }
- else {
- for (unsigned u = 0; u < max_count; ++u)
- input.push_back((base_value << remaining_bits) +
- (rand() % (1 << remaining_bits)));
- }
- }
- //Tests spreadsort on the worst-case distribution for standard MSD radix sorts.
- int main(int, const char **) {
- vector<DATA_TYPE> input;
- for (int ii = (1 << top_splits) - 1; ii >= 0; --ii)
- fill_vector(input, ii, (sizeof(DATA_TYPE) * 8) - top_splits);
- //Run both std::sort and spreadsort
- for (unsigned u = 0; u < 2; ++u) {
- vector<DATA_TYPE> array = input;
- clock_t start, end;
- double elapsed;
- start = clock();
- if (u)
- std::sort(array.begin(), array.end());
- else
- boost::sort::spreadsort::spreadsort(array.begin(), array.end());
- end = clock();
- elapsed = static_cast<double>(end - start);
- if (u)
- printf("std::sort elapsed time %f\n", elapsed / CLOCKS_PER_SEC);
- else
- printf("spreadsort elapsed time %f\n", elapsed / CLOCKS_PER_SEC);
- array.clear();
- }
- return 0;
- }
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