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- // spreadsort float functor sorting example.
- //
- // Copyright Steven Ross 2009.
- //
- // 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.
- // Caution: this file contains Quickbook markup as well as code
- // and comments, don't change any of the special comment markups!
- #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;
- //[float_functor_types
- #define CAST_TYPE int
- #define KEY_TYPE float
- //] [/float_functor_types]
- //[float_functor_datatypes
- struct DATA_TYPE {
- KEY_TYPE key;
- std::string data;
- };
- //] [/float_functor_datatypes]
- //[float_functor_rightshift
- // Casting to an integer before bitshifting
- struct rightshift {
- int operator()(const DATA_TYPE &x, const unsigned offset) const {
- return float_mem_cast<KEY_TYPE, CAST_TYPE>(x.key) >> offset;
- }
- };
- //] [/float_functor_rightshift]
- //[float_functor_lessthan
- struct lessthan {
- bool operator()(const DATA_TYPE &x, const DATA_TYPE &y) const {
- return x.key < y.key;
- }
- };
- //] [/float_functor_lessthan]
- // Pass in an argument to test std::sort
- // Note that this converts NaNs and -0.0 to 0.0, so that sorting results are
- // identical every time
- int main(int argc, const char ** argv) {
- size_t uCount,uSize=sizeof(DATA_TYPE);
- bool stdSort = false;
- unsigned loopCount = 1;
- for (int u = 1; u < argc; ++u) {
- if (std::string(argv[u]) == "-std")
- stdSort = true;
- else
- loopCount = atoi(argv[u]);
- }
- std::ifstream input("input.txt", std::ios_base::in | std::ios_base::binary);
- if (input.fail()) {
- printf("input.txt could not be opened\n");
- return 1;
- }
- double total = 0.0;
- std::vector<DATA_TYPE> array;
- input.seekg (0, std::ios_base::end);
- size_t length = input.tellg();
- uCount = length/uSize;
- //Run multiple loops, if requested
- for (unsigned u = 0; u < loopCount; ++u) {
- input.seekg (0, std::ios_base::beg);
- //Conversion to a vector
- array.resize(uCount);
- unsigned v = 0;
- while (input.good() && v < uCount) {
- input.read(reinterpret_cast<char *>(&(array[v].key)),
- sizeof(array[v].key));
- //Checking for denormalized numbers; float_sort looks too fast on them.
- if (!(float_mem_cast<KEY_TYPE, CAST_TYPE>(array[v].key) & 0x7f800000)) {
- //Make the top exponent bit high
- CAST_TYPE temp = 0x40000000 |
- float_mem_cast<KEY_TYPE, CAST_TYPE>(array[v].key);
- memcpy(&(array[v].key), &temp, sizeof(KEY_TYPE));
- }
- //Testcase doesn't sort NaNs; they just cause confusion
- if (!(array[v].key < 0.0) && !(0.0 < array[v].key))
- array[v].key = 0.0;
- //Adding the data, in this case a string
- std::stringstream intstr;
- intstr << array[v].key;
- array[v].data = intstr.str();
- ++v;
- }
- clock_t start, end;
- double elapsed;
- start = clock();
- if (stdSort)
- std::sort(array.begin(), array.end(), lessthan());
- else
- float_sort(array.begin(), array.end(), rightshift(), lessthan());
- end = clock();
- elapsed = static_cast<double>(end - start) ;
- std::ofstream ofile;
- if (stdSort)
- ofile.open("standard_sort_out.txt", std::ios_base::out |
- std::ios_base::binary | std::ios_base::trunc);
- else
- ofile.open("boost_sort_out.txt", std::ios_base::out |
- std::ios_base::binary | std::ios_base::trunc);
- if (ofile.good()) {
- for (unsigned v = 0; v < array.size(); ++v) {
- ofile.write(reinterpret_cast<char *>(&(array[v].key)),
- sizeof(array[v].key));
- ofile << array[v].data;
- }
- ofile.close();
- }
- total += elapsed;
- array.clear();
- }
- if (stdSort)
- printf("std::sort elapsed time %f\n", total / CLOCKS_PER_SEC);
- else
- printf("spreadsort elapsed time %f\n", total / CLOCKS_PER_SEC);
- return 0;
- }
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