#include <iostream>
using namespace std;
struct Semaphore {
int value;
// q contains all Process Control Blocks(PCBs)
// corresponding to processes got blocked
// while performing down operation.
Queue<process> q;
} P(Semaphore s)
{
s.value = s.value - 1;
if (s.value < 0) {
// add process to queue
// here p is a process which is currently executing
q.push(p);
block();
}
else
return;
}
V(Semaphore s)
{
s.value = s.value + 1;
if (s.value <= 0) {
// remove process p from queue
Process p = q.pop();
wakeup(p);
}
else
return;
}
