//======================================================== file = lec5b.c =====
//=  Program to generate simulated page counts for print jobs                 =
//=============================================================================
//=  Build: bcc32 lec5b.c, cl lec5b.c, gcc lec5b.c                            =
//=---------------------------------------------------------------------------=
//=  Execute: lec5b                                                           =
//=---------------------------------------------------------------------------=
//=  History: KJC (05/30/13) - Refresh from old version                       =
//=============================================================================
#include <stdio.h>              // Needed for printf()
#include <stdlib.h>             // Needed for rand() and RAND_MAX

//----- Constants -------------------------------------------------------------
#define NUM_MEAS      10        // Number of measurements in "bins"
#define NUM_SAMPLES   20        // Number of print job samples to simulate

//----- Globals ---------------------------------------------------------------
struct print_job                // Structure for holding print job samples
{
  int    print_size;            //  ** Page count for this print job
  double ratio_observed;        //  ** Observed ratio (0 to 1) for this sample
};

// Observed print job samples where sum of ratios must equal one
struct print_job size[NUM_MEAS] = { {2,  0.22}, {3,  0.31}, {4,  0.16},
                                    {5,  0.09}, {6,  0.07}, {7,  0.05},
                                    {8,  0.04}, {9,  0.03}, {10, 0.02},
                                    {11, 0.01} };

//===== Main program ==========================================================
void main(void)
{
  double dist_func[NUM_MEAS];   // The CDF for the print job samples
  double z;                     // Uniform random number from 0 to 1
  int bin_num;                  // Measurement "bin" number
  int page_count;               // Final page count for this sample
  int i;                        // Loop counter

  // <#1> Build the CDF for the observed measurements
  dist_func[0] = size[0].ratio_observed;
  for (i=1; i<NUM_MEAS; i++)
    dist_func[i] = dist_func[i-1] + size[i].ratio_observed;

  // <#2> Output the CDF values
  for (i=0; i<NUM_MEAS; i++)
    printf("dist_func[%ld] = %f \n", i, dist_func[i]);

  // <#3> Generate NUM_SAMPLES print jobs
  for (i=0; i<NUM_SAMPLES; i++)
  {
    // <#3a> Pull a uniform RV (0 < z < 1)
    do
    {
      z = ((double) rand() / RAND_MAX);
    }
    while ((z == 0) || (z == 1));

    // <#3b> Map z to a bin number
    for (bin_num=0; bin_num<NUM_MEAS; bin_num++)
      if (z < dist_func[bin_num])
      {
        // <#3c> Get page_count as print_size from selected bin
        page_count = size[bin_num].print_size;
        break;
      }

    // <#3d> Output simulated page count
    printf("Sample #%d -- page count = %d \n", i, page_count);
  }
}