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random.c
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random.c
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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int parse_arguments(int argc, char *argv[])
{
int table_size;
if (argc == 2 && (table_size = atoi(argv[1])))
{
return table_size;
}
fprintf(stderr, "Wrong arguments, Pass table_size as an argument\n");
exit(-1);
}
struct Page
{
int value;
struct Page *next;
};
struct Page *head = NULL;
struct Page *current = NULL; // current - last page in list
int list_size()
{
struct Page *ptr = head;
int counter=0;
while(ptr != head)
{
counter++;
ptr = ptr->next;
}
return counter;
}
// search list for a specific page
struct Page* search_list(int value, struct Page **previous)
{
struct Page *ptr = head;
struct Page *temp = NULL;
while (ptr != NULL)
{
if (ptr->value == value)
{
if(previous)
*previous = temp;
return ptr;
}
else
{
temp = ptr;
ptr = ptr->next;
}
}
return NULL;
}
// create a linked list
struct Page* create_list(int value)
{
struct Page *ptr = (struct Page*) malloc(sizeof(struct Page));
if (ptr == NULL)
{
fprintf(stderr, "Could not create the page!");
return NULL;
}
ptr->value = value;
ptr->next = NULL;
head = current = ptr;
return ptr;
}
// insert page to head
struct Page* insert_front(int value)
{
if(head == NULL)
{
return (create_list(value));
}
struct Page *ptr = (struct Page*)malloc(sizeof(struct Page));
if (ptr == NULL)
{
fprintf(stderr, "Could not create the Page!");
return NULL;
}
ptr->value = value;
ptr->next = head;
head = ptr;
return ptr;
}
// search list for a specific page and delete it
int remove_list(int value)
{
struct Page *delet = NULL;
struct Page *previous = NULL;
delet = search_list(value, &previous);
if(delet == NULL)
return -1;
else
{
if(previous != NULL)
previous->next = delet->next;
if(delet == current)
current = previous;
if (delet == head)
head = delet->next;
}
free(delet);
delet = NULL;
return 0;
}
// insert page to tail
struct Page* insert_tail(int value)
{
if(head == NULL)
{
return (create_list(value));
}
struct Page *ptr = (struct Page*)malloc(sizeof(struct Page));
if (ptr == NULL)
{
fprintf(stderr, "Page creation failed!");
return NULL;
}
ptr->value = value;
ptr->next = NULL;
current->next = ptr;
current = ptr;
return ptr;
}
// pre: a table size and a page request
// post: TRUE or FALSE -> TRUE if page fault, FALSE if no page fault
int random_page(int table_size, int page_request)
{
struct Page *ptr = NULL;
struct Page *previous = NULL;
int count = 0;
srand((int) time(NULL));
ptr = search_list(page_request, &previous);
// page fault
if (ptr == NULL)
{
ptr = head;
// Track count of size
while (ptr != NULL)
{
ptr = ptr->next;
count++;
}
if (count == table_size)
{
ptr = head;
int num = rand()%(list_size() - 1);
while(num > 0)
{
ptr = ptr->next;
--num;
}
int val = ptr->value;
ptr = head;
insert_tail(page_request);
remove_list(val);
}
// Insert at back
else
{
insert_tail(page_request);
}
return 1;
}
return 0;
}
int main(int argc, char*argv[])
{
int table_size = parse_arguments(argc, argv);
int page_request;
int num_requests = 0;
int num_misses = 0;
int *page_table = (int *) malloc(sizeof(int)*table_size);
char *input = NULL;
size_t input_allocated = 0;
ssize_t bytes_read;
while ((bytes_read = getline(&input, &input_allocated, stdin)) != -1)
{
page_request = atoi(input);
num_requests++;
if (page_request == 0)
continue;
// Here is where we make use of the P.R.A.
// The P.R.A. will return 1 if there is a page fault, helping us count misses
if(random_page(table_size,page_request))
{
printf("Page %d caused a page fault\n", page_request);
num_misses++;
}
}
// number of hits = num_requests-num_misses
// hit rate = hits/requests
printf("Hit rate: %f\n", (num_requests-num_misses)/(double)num_requests);
free(input);
free(page_table);
return 0;
return 0;
}