binary semaphore code

threads-sema/binary.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+
+#include "common.h"
+#include "common_threads.h"
+
+sem_t mutex;
+volatile int counter = 0;
+
+void *child(void *arg) {
+    int i;
+    for (i = 0; i < 10000000; i++) {
+	Sem_wait(&mutex);
+	counter++;
+	Sem_post(&mutex);
+    }
+    return NULL;
+}
+
+int main(int argc, char *argv[]) {
+    Sem_init(&mutex, 1); 
+    pthread_t c1, c2;
+    Pthread_create(&c1, NULL, child, NULL);
+    Pthread_create(&c2, NULL, child, NULL);
+    Pthread_join(c1, NULL);
+    Pthread_join(c2, NULL);
+    printf("result: %d\n", counter);
+    return 0;
+}
+