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

   1 // flexible random number generator providing multiple distributions.
   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/random/mersenne_twister.hpp>
  12 #include <boost/random/uniform_int_distribution.hpp>
  13 #include <stdio.h>
  14 #include "stdlib.h"
  15 #include <fstream>
  16 #include <iostream>
  17 using namespace boost;
  18
  19 int main(int argc, const char ** argv) {
  20   random::mt19937 generator;
  21   random::uniform_int_distribution<unsigned> distribution;
  22   //defaults
  23   unsigned high_shift = 16;
  24   unsigned low_shift = 16;
  25   unsigned count = 1000000;
  26   //Reading in user arguments
  27   if (argc > 1)
  28     high_shift = atoi(argv[1]);
  29   if (argc > 2)
  30     low_shift = atoi(argv[2]);
  31   if (argc > 3)
  32     count = atoi(argv[3]);
  33   if (high_shift > 16)
  34     high_shift = 16;
  35   if (low_shift > 16)
  36     low_shift = 16;
  37   std::ofstream ofile;
  38   ofile.open("input.txt", std::ios_base::out | std::ios_base::binary |
  39              std::ios_base::trunc);
  40   if (ofile.bad()) {
  41     printf("could not open input.txt for writing!\n");
  42     return 1;
  43   }
  44   //buffering file output for speed
  45   unsigned uDivideFactor = 1000;
  46   //Skipping buffering for small files
  47   if (count < uDivideFactor * 100)
  48     uDivideFactor = count;
  49   unsigned * pNumbers = static_cast<unsigned *>(malloc(uDivideFactor *
  50                                                        sizeof(unsigned)));
  51   //Generating semirandom numbers
  52   unsigned mask = 0;
  53   unsigned one = 1;
  54   for (unsigned u = 0; u < low_shift; ++u) {
  55     mask += one << u;
  56   }
  57   for (unsigned u = 0; u < high_shift; ++u) {
  58     mask += one << (16 + u);
  59   }
  60   for (unsigned u = 0; u < count/uDivideFactor; ++u) {
  61     unsigned i = 0;
  62     for (; i< uDivideFactor; ++i) {
  63       pNumbers[i] = distribution(generator) & mask;
  64     }
  65     ofile.write(reinterpret_cast<char *>(pNumbers), uDivideFactor * 4 );
  66   }
  67   ofile.close();
  68   return 0;
  69 }