extended code to advanced input functionality

OS/C/theory/sync/withsema.c

@@ -1,32 +1,33 @@
+#include <stdatomic.h>
 #include <stdio.h>
 #include <pthread.h>
 #include <semaphore.h>
-#include <sys/semaphore.h>
+#include <dispatch/dispatch.h>
 
-int counter = 0; // shared resource
-sem_t semaphore; // semaphore declaration
+atomic_int counter = 0; // shared resource
+dispatch_semaphore_t semaphore; // semaphore declaration
 
 void* increment(void* arg) {
     for (int i = 0; i < 100000; i++) {
-        sem_wait(&semaphore); // lock
-        counter++; // critical section
-        sem_post(&semaphore); // unlock
+        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER); // lock
+        atomic_fetch_add(&counter, 1); // critical section
+        dispatch_semaphore_signal(semaphore); // unlock
     }
     return NULL;
 }
 
 int main() {
     pthread_t t1, t2;
-    sem_init(&semaphore, 0, 1); // initialize semaphore with value 1
+    semaphore = dispatch_semaphore_create(1); // initialize semaphore with value 1
 
     pthread_create(&t1, NULL, increment, NULL);
     pthread_create(&t2, NULL, increment, NULL);
     pthread_join(t1, NULL);
     pthread_join(t2, NULL);
 
-    sem_destroy(&semaphore);
+    dispatch_release(semaphore);
 
-    printf("Final Counter Value (with semaphores): %d\n", counter);
+    printf("Final Counter Value (with semaphores): %d\n", atomic_load(&counter));
 
     return 0;
 }