ceph/src/boost/libs/sort/example/floatsample.cpp

   1 // spreadsort float 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>
  20 using namespace boost::sort::spreadsort;
  21
  22 #define DATA_TYPE float
  23 #define CAST_TYPE int
  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
  28 int 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(argv[u]);
  37   }
  38   std::ifstream input("input.txt", std::ios_base::in | std::ios_base::binary);
  39   if (input.fail()) {
  40     printf("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   //Run multiple loops, if requested
  49   for (unsigned u = 0; u < loopCount; ++u) {
  50     input.seekg (0, std::ios_base::beg);
  51     //Conversion to a vector
  52     array.resize(uCount);
  53     unsigned v = 0;
  54     while (input.good() && v < uCount) {
  55       input.read(reinterpret_cast<char *>(&(array[v])), uSize );
  56      //Checking for denormalized numbers
  57      if (!(float_mem_cast<float, int>(array[v]) & 0x7f800000)) {
  58        //Make the top exponent bit high
  59        CAST_TYPE temp = 0x40000000 | float_mem_cast<float, int>(array[v]);
  60        memcpy(&(array[v]), &temp, sizeof(DATA_TYPE));
  61      }
  62      //Testcase doesn't sort NaNs; they just cause confusion
  63      if (!(array[v] < 0.0) && !(0.0 < array[v]))
  64       array[v] = 0.0;
  65      ++v;
  66     }
  67     clock_t start, end;
  68     double elapsed;
  69     start = clock();
  70     if (stdSort)
  71       //std::sort(&(array[0]), &(array[0]) + uCount);
  72       std::sort(array.begin(), array.end());
  73     else
  74       //boost::sort::spreadsort::spreadsort(&(array[0]), &(array[0]) + uCount);
  75       boost::sort::spreadsort::spreadsort(array.begin(), array.end());
  76     end = clock();
  77     elapsed = static_cast<double>(end - start) ;
  78     std::ofstream ofile;
  79     if (stdSort)
  80       ofile.open("standard_sort_out.txt", std::ios_base::out |
  81                  std::ios_base::binary | std::ios_base::trunc);
  82     else
  83       ofile.open("boost_sort_out.txt", std::ios_base::out |
  84                  std::ios_base::binary | std::ios_base::trunc);
  85     if (ofile.good()) {
  86       for (unsigned v = 0; v < array.size(); ++v) {
  87         ofile.write(reinterpret_cast<char *>(&(array[v])), sizeof(array[v]) );
  88       }
  89       ofile.close();
  90     }
  91     total += elapsed;
  92     array.clear();
  93   }
  94   input.close();
  95   if (stdSort)
  96     printf("std::sort elapsed time %f\n", total / CLOCKS_PER_SEC);
  97   else
  98     printf("spreadsort elapsed time %f\n", total / CLOCKS_PER_SEC);
  99   return 0;
 100 }