OS-practical/slip1_1.c at main · mukmal/OS-practical · GitHub

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#include<stdio.h>
#define MAX 20
int frames[MAX],ref[MAX],mem[MAX][MAX],faults,
sp,m,n,count[MAX];
void accept()
{
int i;
printf("Enter no.of frames:");
scanf("%d", &n);
printf("Enter no.of references:");
scanf("%d", &m);
printf("Enter reference string:\n");
for(i=0;i<m;i++)
{
printf("[%d]=",i);
scanf("%d",&ref[i]);
}
}
void disp()
{
int i,j;
for(i=0;i<m;i++)
printf("%3d",ref[i]);
printf("\n\n");
for(i=0;i<n;i++)
 {
  for(j=0;j<m;j++)
  {
   if(mem[i][j])
    printf("%3d",mem[i][j]);
   else
    printf("   ");
  }
  printf("\n");
 }
 printf("Total Page Faults: %d\n",faults);
}
int search(int pno)
{
 int i;
 for(i=0;i<n;i++)
 {
  if(frames[i]==pno)
   return i;
 }
 return -1;
}
int get_lfu(int sp)
{
 int i,min_i,min=9999;
 i=sp;
 do
 {
  if(count[i]<min)
  {
   min = count[i];
   min_i = i;
  }
  i=(i+1)%n;
 }while(i!=sp);
 return min_i;
}
void lfu()
{
 int i,j,k;
 for(i=0;i<m && sp<n;i++)
 {
  k=search(ref[i]);
  if(k==-1)
  {
   frames[sp]=ref[i];
   count[sp]++;
   faults++;
   sp++;
   for(j=0;j<n;j++)
    mem[j][i]=frames[j];
  }
  else
   count[k]++;
 }
 sp=0;
 for(;i<m;i++)
 {
  k = search(ref[i]);
  if(k==-1)
  {
   sp = get_lfu(sp);
   frames[sp] = ref[i];
   count[sp]=1;
   faults++;
   sp = (sp+1)%n;
   for(j=0;j<n;j++)
    mem[j][i] = frames[j];
  }
  else
   count[k]++;
 }
}
int main()
{
 accept();
 lfu();
 disp();
 return 0;
}