FIFO.c

#include <stdio.h>
#include <stdbool.h>
#include <string.h>

struct PageTable
{
  int frame_no;
  bool valid;
};

bool isPagePresent(struct PageTable PT[], int page, int n)
{
  if (PT[page].valid == 1)
    return true;
  return false;
}

void updatePageTable(struct PageTable PT[], int page, int fr_no, int status)
{
  PT[page].valid = status;

  PT[page].frame_no = fr_no;
}

void printFrameContents(int frame[], int no_of_frames)
{
  for (int i = 0; i < no_of_frames; i++)
    printf("%d ", frame[i]);
  printf("\n");
}

int main()
{
  int i, n, no_of_frames, page_fault = 0, current = 0;
  bool flag = false;
  printf("\n Enter the no. of pages:\n");
  scanf("%d", &n);

  int reference_string[n];
  printf("\n Enter the reference string(different page numbers) :\n");
  for (int i = 0; i < n; i++)
    scanf("%d", &reference_string[i]);
  printf("\n Enter the no. of frames you want to give to the process :");
  scanf("%d", &no_of_frames);

  int frame[no_of_frames];
  memset(frame, -1, no_of_frames * sizeof(int));
  struct PageTable PT[50];
  for (int i = 0; i < 50; i++)
    PT[i].valid = 0;

  printf("\n****The Contents inside the Frame array at different time:****\n");
  for (int i = 0; i < n; i++)
  {

    if (!(isPagePresent(PT, reference_string[i], n)))
    {
      page_fault++;
      if (flag == false && current < no_of_frames)
      {
        frame[current] = reference_string[i];
        printFrameContents(frame, no_of_frames);
        updatePageTable(PT, reference_string[i], current, 1);
        current = current + 1;
        if (current == no_of_frames)
        {
          current = 0;
          flag = true;
        }
      }

      else
      {

        updatePageTable(PT, frame[current], -1, 0);
        frame[current] = reference_string[i];
        printFrameContents(frame, no_of_frames);
        updatePageTable(PT, reference_string[i], current, 1);
        current = (current + 1) % no_of_frames;
      }
    }
  }

  printf("\nTotal No. of Page Faults = %d\n", page_fault);
  printf("\nPage Fault ratio = %.2f\n", (float)page_fault / n);
  printf("\nPage Hit Ratio = %.2f\n", (float)(n - page_fault) / n);
  return 0;
}