As for each client there is different message no. so in case of message queue technique there is no need of synchronization the clients.

in semaphore we use system calls- up and down
before entering into critical section the integer semaphore value is decremented by using down and it is incremented using call up after critical section.

Completion is another kernel level synchronization technique that has advantage over semaphore that it is light weight operation. It does not require any weight queue…….the calls used in completion are- wait_for_copmletion and complete and also complete_all.

Spinlock is used in process that cannot sleep such as interrupt handler. In spinlock execution in critical section is atomic,non_interruptable.The calls used in spinlock are spin_lock and spin_unlock.

The NULL pointer is a constant with a value of zero defined in several standard libraries ex.-

On most of the operating systems, programs are not permitted to access memory at address 0 because that memory is reserved by the operating system. However, the memory address 0 has special significance; it signals that the pointer is not intended to point to an accessible memory location. But by convention, if a pointer contains the null (zero) value, it is assumed to point to nothing.

1.1
date 2014.03.27.10.47.56; author root; state Exp;
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1.1
log
@Initial revision
@
text
@#include
#include
struct node
{
int data;
struct node * next;
};
struct node * create_ll( );
struct node * insert_ll(struct node * );
struct node * insert_beg(struct node * );
struct node * insert_pos(struct node * );
struct node * insert_end(struct node * );
struct node * delete_ll(struct node * );
struct node * delete_beg(struct node * );
struct node * delete_pos(struct node * );
struct node * delete_end(struct node * );
struct node * display_ll(struct node * );
int main()
{
struct node * start;
int ch;
do
{
printf(“\n1 create linklist”);
printf(“\n2 insert linklist”);
printf(“\n3 delete linklist”);
printf(“\n4 display linklist”);
printf(“\n5 quit”);
printf(“\n enter the choice”);
scanf(“%d”,&ch);

switch(ch)
{
case 1:
start=create_ll();
break;
case 2:
start=insert_ll(start);
break;
case 3:
start=delete_ll(start);
break;
case 4:
start=display_ll(start);
break;
}
}while(ch != 5);
return 0;
}
struct node * create_ll()
{
struct node * temp;
temp=malloc(sizeof(struct node));
printf(“enter the data”);
scanf(“%d”,&temp->data);
temp->next=NULL;
return temp;
}
struct node * insert_ll(struct node * start )
{
int ch;
printf(“\n1 insert at the beg”);
printf(“\n2 insert at the pos”);
printf(“\n3 insert at the end”);
printf(“\n enter the choice”);
scanf(“%d”,&ch);
switch(ch)
{
case 1:
start=insert_beg(start);
break;
case 2:
start=insert_pos(start);
break;
case 3:
start=insert_end(start);
break;

}

return start;
}
struct node * delete_ll(struct node * start )
{
int ch;
printf(“\n1 delete at the beg”);
printf(“\n2 delete at the pos”);
printf(“\n3 delete at the end”);
printf(“\n enter the choice”);
scanf(“%d”,&ch);
switch(ch)
{
case 1:
start=delete_beg(start);
break;
case 2:
start=delete_pos(start);
break;
case 3:
start=delete_end(start);
break;
}
return start;
}

struct node * display_ll(struct node * start)
{
struct node * temp;
temp=start;
while(temp!=NULL)
{
printf(“entered data is %d”,temp->data);
temp=temp->next;

}
return start;
}
struct node * insert_beg(struct node * start)
{
struct node * temp;
temp=create_ll();
temp->next=start;
start=temp;
return start;

}
struct node * insert_pos(struct node * start)
{
int i,n;
struct node * temp,* new;
temp=start;
new=create_ll();
printf(“enter the position to be inserted”);
scanf(“%d”,&n);
for(i=0;inext;
}
new->next=temp->next;
temp->next=new;
return start;

}
struct node * insert_end(struct node * start)
{
struct node * temp,* new;
temp=start;
new=create_ll();
while(temp->next!=NULL)
{
temp=temp->next;
}
temp->next=new;
new->next=NULL;
return start;
}
struct node * delete_beg(struct node * start)
{
struct node * temp;
temp=start;
start=start->next;;
free(temp);
return start;
}
struct node * delete_pos(struct node * start)
{
struct node * temp,* pre;
int i,m;
temp=start;
printf(“\nenter the position”);
scanf(“%d”,&m);
for(i=0;inext;
}
pre->next=temp->next;
free(temp);
return start;
}
struct node * delete_end(struct node * start)
{
struct node * temp,*pre;
temp=start;
while(temp->next!=NULL)
{
pre=temp;
temp=temp->next;
}
free(temp);
pre->next=NULL;
return start;

}