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cscan.c
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cscan.c
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#include<stdio.h>
#include<stdlib.h>
#include<time.h>
void main()
{
srand(time(0));
int n, tr[20],init,i,j,seek=0,current,next=-1,count,max,r,oneseek;
char dir;
double avg;
//printf("\nEnter l for left r for right:\t");
//scanf("%c",&dir);
r=rand()%2;
oneseek=rand()%3+1;
if(r==0)
{
printf("\nDirection:\tLeft");
dir='l';
}
else
{
printf("\nDirection:\tRight");
dir='r';
}
printf("\nSeek time for each track:\t%dms",oneseek);
//printf("\nEnter number of requests:\t");
//scanf("%d",&n);
n=rand()%5+2;
printf("\nNo. of requests:\t%d",n);
//printf("\nEnter range of disk:\t");
//scanf("%d",&max);
max=rand()%(200-100+1)+100;
printf("\nMaximum range of disk:\t%d",max);
//printf("\nEnter initial head postition:\t");
//scanf("%d",&init);
init=rand()%(max+1);
printf("\nInitial head position:\t%d",init);
printf("\n\nRequests:\t");
for(i=0;i<n;i++)
{
//scanf("%d",&tr[i]);
tr[i]=rand()%max;
printf("%d\t",tr[i]);
}
for(i=0;i<n;i++)
{
current=i;
for(j=i+1;j<n;j++)
{
if(tr[j]<tr[current])
current=j;
}
int temp=tr[current];
tr[current]=tr[i];
tr[i]=temp;
}
current=init;
printf("\n\nSequence is:\t%d\t",init);
switch(dir)
{
case 'l':
for(i=n-1;i>=0;i--)
if(tr[i]<current)
{next=i;break;}
if(next==-1)//case that all requests are >current
{
printf("0\t%d\t",max);
seek+=current;
next=n-1;
current=max;
}
break;
case 'r':
for(i=0;i<n;i++)
if(tr[i]>current)
{next=i;break;}
if(next==-1)//case that all requests are <current
{
printf("%d\t0\t",max);
seek+=abs(current-max);
current=0;
next=0;
}
break;
}
count=n;
//printf("\ncount:%d",count);
while(count>0)
{
//printf("\ncount:%d",count);
switch(dir)
{
case 'l': //printf("\nGoing left");
for(j=next;j>=0;j--)
{
count--;
printf("%d\t",tr[j]);
seek+=abs(tr[j]-current);
current=tr[j];
if(count==0)
break;
}
if(tr[0]!=0 && count!=0)//to avoid printing duplicate
{
//printf("tr%d",tr[0]);
seek+=current;
printf("0\t");
if(tr[n-1]!=max)
printf("%d\t",max);
current=max;
}
next=n-1;
break;
case 'r': //printf("\nGoing right");
for(j=next;j<n;j++)
{
count--;
printf("%d\t",tr[j]);
seek+=abs(tr[j]-current);
current=tr[j];
if(count==0)
break;
}
if(tr[n-1]!=max && count!=0)//to avoid printing duplicate
{
seek+=abs(current-max);
printf("%d\t",max);
if(tr[0]!=0)
printf("0\t");
current=0;
}
next=0;
break;
default:printf("\nInvalid choice");
}
}
printf("\nTotal head movement:\t%d\n",seek);
avg=oneseek*seek/(1.0*n);
printf("\nAverage seek time:\t%.2f\n",avg);
}