I Consider the following snapshot of a system:
|
|
Allocation |
Max |
|||||||
|
|
A |
B |
C |
A |
B |
C |
|||
|
P0 |
0 |
1 |
0 |
7 |
5 |
3 |
|||
|
P1 |
2 |
0 |
0 |
3 |
2 |
2 |
|||
|
P2 |
3 |
0 |
2 |
9 |
0 |
2 |
|||
|
P3 |
2 |
1 |
1 |
2 |
2 |
2 |
|||
|
P4 |
0 |
0 |
2 |
4 |
3 |
3 |
|||
|
Available |
|
||||||||
|
A |
B |
C |
|
||||||
|
3 |
3 |
2 |
|
||||||
Add
the following functionalities in your program
1. Accept
Available
2. Display
Allocation, Max, Need matrix, Available
3. Accept
Request for a process, if a request from process P1 arrives for (1, 0, 2) can
it be immediately granted?
4. Accept
Request and Apply Banker’s Algorithm
5. Exit
Solution:
#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
int max[10][10],need[10][10],allocation[10][10];
int available[10],work[10],finish[10],request[10],Safe[10];
int np,nr,i,j,k,l,m,n,pid,pno;
int ch,cnt=0;
void accept_matrix(int A[10][10])
{
int i,j;
for(i=0;i<np;i++)
{
for(j=0;j<nr;j++)
{
scanf("%d",&A[i][j]);
}
}
}
void Accept_Vector(int A[])
{
int i;
for(i=0;i<nr;i++)
{
scanf("%d",&A[i]);
}
}
void Find_need()
{
int i, j;
for(i=0;i<np;i++)
{
for(j=0;j<nr;j++)
{
need[i][j]=max[i][j]-allocation[i][j];
}
}
printf("\nNeed Calculated Successfully\n");
}
void Display_matrix()
{
int i,j;
printf("\nAllocation\tMax\t\tNeed\n");
for(i=0; i<np;i++)
{
for(j=0; j<nr;j++)
printf(" %d",allocation[i][j]) ;
printf("\t\t");
for (j=0; j<nr;j++)
printf(" %d",max[i][j]) ;
printf("\t\t");
for (j=0; j<nr;j++)
printf(" %d",need[i][j]) ;
printf("\n");
}
printf("\n Available\n");
for (j=0; j<nr;j++)
printf(" %d",available[j]);
printf("\t");
}
int Safety_algo()
{
int over =0, i, j, k,l=0,flag=0,pflag=0;
//initialize work = available
for(i=0;i<nr;i++)
work[i]=available[i];
for(i=0;i<np;i++)
finish[i]=0;
while(!over)
{ // check for any not finished process
for(i=0;i<np; i++)
{
if(finish[i] == 0)
{
flag=0;
for(j=0;j<nr;j++)
{
if(need[i][j]>work[j])
flag=1;
}
if(flag == 0 && finish[i] == 0)
{
for(j=0;j<nr;j++)
work[j]+=available[j];
finish[i]=1;
pflag++;
Safe[l++]=i;
}
}
if(pflag == n)
{
over = 1;
return 1;
}
}
}
return 0;
}
void Bankers_algo()
{
int i,j;
j=Safety_algo();
if(j != 0 )
{
printf("\n A safety sequence has been detected.\n");
for(i=0;i<np;i++)
printf(" P%d ",Safe[i]);
}
else
{
printf("\n Deadlock has occured.\n");
}
}
void Resource_request_algo()
{
int i;
// check if requesti <= needi
for(i=0;i<nr;i++)
{
if(request[i]>need[pno][i])
{
printf("error.. process exceeds its Max demand");
exit(1);
}
}
// check if Reuest [i] <= availableable
for(i=0; i<np; i++)
{
if(request[i] > available[i])
{
printf("Process must wait , resources not available");
exit(1);
}
}
// pretend to have allocated requested resources
for(i=0;i<np;i++)
{
available[i]=available[i]-request[i];
allocation[pno][i]=allocation[pno][i]+request[i];
need[pno][i]=need[pno][i]-request[i];
}
printf("\nRun Safety\n");
//run Safety algorithm to check whether safe sequence exists or not
Bankers_algo();
}
int main()
{
//clrscr();
int result;
printf("\n Enter the no of processes:\t");
scanf("%d",&np);
printf("\n Enter the no of resources:\t");
scanf("%d",&nr);
do
{
printf("\n\n--------MENU------------");
printf("\n\n1.Accept allocation:\n2.Accept Max:\n3.Calculate need\n4.Accept available\n");
printf("5.Display Matrices\n6.Apply Bankers Algorithm\n7.Accept Request and Apply Banker’s Algorithm\n7.exit:");
printf("\n\n Enter your choice:");
scanf("%d",&ch);
switch(ch)
{
case 1: printf("\n Enter the allocation matrix:\n");
accept_matrix(allocation);
break;
case 2: printf("\n Enter the max matrix:\n");
accept_matrix(max);
break;
case 3:Find_need();
break;
case 4: printf("\n Enter the available vector:\n");
Accept_Vector(available);
break;
case 5:Display_matrix();
break;
case 6:
printf("\nApplying Bankers Algorithm\n");
Bankers_algo();
break;
case 7:
printf("\nEnter The Process Number\n");
scanf("%d",&pno);
printf("\nEnter the Request vector\n");
Accept_Vector(request);
Resource_request_algo();
break;
}
}while(ch!=8);
return 0;
}
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