1// spreadsort double sorting example.
2//
3// Copyright Steven Ross 2009-2014.
4//
5// Distributed under the Boost Software License, Version 1.0.
6// (See accompanying file LICENSE_1_0.txt or copy at
7// http://www.boost.org/LICENSE_1_0.txt)
8
9// See http://www.boost.org/libs/sort for library home page.
10
11#include <boost/sort/spreadsort/spreadsort.hpp>
12#include <time.h>
13#include <stdio.h>
14#include <stdlib.h>
15#include <algorithm>
16#include <vector>
17#include <string>
18#include <fstream>
19#include <iostream>
20using namespace boost::sort::spreadsort;
21
22#define DATA_TYPE double
23#define CAST_TYPE boost::int64_t
24
25//Pass in an argument to test std::sort
26//Note that this converts NaNs and -0.0 to 0.0, so that sorting results are
27//identical every time
28int main(int argc, const char ** argv) {
29 size_t uCount,uSize=sizeof(DATA_TYPE);
30 bool stdSort = false;
31 unsigned loopCount = 1;
32 for (int u = 1; u < argc; ++u) {
33 if (std::string(argv[u]) == "-std")
34 stdSort = true;
35 else
36 loopCount = atoi(nptr: argv[u]);
37 }
38 std::ifstream input("input.txt", std::ios_base::in | std::ios_base::binary);
39 if (input.fail()) {
40 printf(format: "input.txt could not be opened\n");
41 return 1;
42 }
43 double total = 0.0;
44 std::vector<DATA_TYPE> array;
45 input.seekg (0, std::ios_base::end);
46 size_t length = input.tellg();
47 uCount = length/uSize;
48 //Using this to support compilers that don't support 64-bit constants
49 CAST_TYPE exponent_mask = 0x7ff00000;
50 exponent_mask <<= 32;
51 CAST_TYPE top_exponent_bit = 0x40000000;
52 top_exponent_bit <<= 32;
53 //Run multiple loops, if requested
54 for (unsigned u = 0; u < loopCount; ++u) {
55 input.seekg (0, std::ios_base::beg);
56 //Conversion to a vector
57 array.resize(new_size: uCount);
58 unsigned v = 0;
59 while (input.good() && v < uCount) {
60 input.read(s: reinterpret_cast<char *>(&(array[v])), n: uSize );
61 //Checking for denormalized numbers
62 if (!(float_mem_cast<DATA_TYPE, CAST_TYPE>(data: array[v]) & exponent_mask)) {
63 //Make the top exponent bit high
64 CAST_TYPE temp = top_exponent_bit |
65 float_mem_cast<DATA_TYPE, CAST_TYPE>(data: array[v]);
66 memcpy(dest: &(array[v]), src: &temp, n: sizeof(DATA_TYPE));
67 }
68 //Testcase doesn't sort NaNs; they just cause confusion
69 if (!(array[v] < 0.0) && !(0.0 < array[v]))
70 array[v] = 0.0;
71 ++v;
72 }
73 clock_t start, end;
74 double elapsed;
75 start = clock();
76 if (stdSort)
77 //std::sort(&(array[0]), &(array[0]) + uCount);
78 std::sort(first: array.begin(), last: array.end());
79 else
80 //float_sort(&(array[0]), &(array[0]) + uCount);
81 float_sort(first: array.begin(), last: array.end());
82 end = clock();
83 elapsed = static_cast<double>(end - start) ;
84 std::ofstream ofile;
85 if (stdSort)
86 ofile.open(s: "standard_sort_out.txt", mode: std::ios_base::out |
87 std::ios_base::binary | std::ios_base::trunc);
88 else
89 ofile.open(s: "boost_sort_out.txt", mode: std::ios_base::out |
90 std::ios_base::binary | std::ios_base::trunc);
91 if (ofile.good()) {
92 for (unsigned v = 0; v < array.size(); ++v) {
93 ofile.write(s: reinterpret_cast<char *>(&(array[v])), n: sizeof(array[v]) );
94 }
95 ofile.close();
96 }
97 total += elapsed;
98 array.clear();
99 }
100 if (stdSort)
101 printf(format: "std::sort elapsed time %f\n", total / CLOCKS_PER_SEC);
102 else
103 printf(format: "spreadsort elapsed time %f\n", total / CLOCKS_PER_SEC);
104 return 0;
105}
106

source code of boost/libs/sort/example/double.cpp