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ping-pong.cpp
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ping-pong.cpp
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#include <iostream>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sched.h>
using namespace std;
int main(int argc, char *argv[]) {
volatile int* counter = (int *)mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE , MAP_SHARED | MAP_ANONYMOUS, -1, 0);
*counter = 1;
int n = strtoul(argv[1], NULL, 10);
if (!fork()) {
while (*counter <= n) {
while ((*counter) % 2 == 0) {
sched_yield();
}
if (*counter > n)
break;
cout << 1 << " " << *counter << endl;
++(*counter);
}
exit(0);
} else if (!fork()) {
while (*counter <= n) {
while ((*counter) % 2 == 1) {
sched_yield();
}
if (*counter > n)
break;
cout << 2 << " " << *counter << endl;
++(*counter);
}
exit(0);
}
wait(NULL);
wait(NULL);
munmap((void *)counter, getpagesize());
return 0;
}