how to do LRU algorithm in terms of a b c code example
Example: lru page replacement algorithm in c
/*
This code is contributed by :
Tanishq Vyas (github : https://github.com/tanishqvyas )
*/
#include <stdlib.h>
#include <stdio.h>
int main(int argc, char const *argv[])
{
int length;
int num_frames;
printf("Enter the length of the reference string : ");
scanf("%d", &length);
char ref_string[length*2];
char hold;
printf("Enter the Reference string : ");
// scanf("%[^\n]%*c", ref_string);
int reference_str[length];
for (int i = 0; i < length; i++)
{
scanf("%d ", &reference_str[i]);
}
scanf("%c", &hold);
scanf("%c", &hold);
printf("Enter the Number of Frames : ");
scanf("%d", &num_frames);
int memory[num_frames];
for (int i = 0; i < num_frames; i++)
{
memory[i] = -1;
}
// LRU
int fault_count = 0;
printf("\n\n The Page Replacement Process Is : \n");
for (int i = 0; i < length; i++)
{
// Get Current Requested Page
int cur_page = reference_str[i];
int page_found = 0;
// Look for page in memory
for(int j = 0; j < num_frames; j++)
{
if(memory[j] == cur_page)
{
page_found = 1;
break;
}
}
// If page is not found
if(!page_found)
{
// Increase Fault Count
fault_count++;
// Cached status : to check for any empty slot
int is_cached = 0;
// <-----------Cache the page --------------->
for(int j = 0; j < num_frames; j++)
{
if(memory[j] == -1)
{
memory[j] = cur_page;
break;
}
}
// If no empty slot is found then remove the LRU page
if(!is_cached)
{
int check_count = 0;
int check_status[num_frames];
for(int m = 0; m < num_frames; m++)
{
check_status[m] = 0;
}
for(int cur = i-1; cur >= 0; cur--)
{
int val = reference_str[cur];
for(int n= 0; n < num_frames; n++)
{
if(val == memory[n])
{
check_status[n] = 1;
check_count++;
break;
}
}
if(check_count == num_frames-1)
break;
}
// Put the page where check status = 0
for(int cur = 0; cur < num_frames; cur++)
{
if(check_status[cur] == 0)
{
memory[cur] = cur_page;
break;
}
}
}
// Print the current Memory snap
for(int j = 0; j < num_frames; j++)
{
printf("%d\t", memory[j]);
}
printf("\tPage Fault Num : %d\n", fault_count);
}
// When page is present in Cache
else
{
// Print the current Memory snap
for(int j = 0; j < num_frames; j++)
{
printf("%d\t", memory[j]);
}
printf("\n");
}
}
printf("\n Total Page Faults : %d\n", fault_count);
return 0;
}