Teil 2)

cars_2.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+
+#define crosses 100000
+#define Car_Number 2
+#define Bridge_Capacity 1 
+int car_on_bridge = 0;
+
+char _lock[Car_Number];
+
+int lock (int thread_id){
+    _lock[thread_id] = 1;
+
+    while (_lock[(thread_id + 1) % Car_Number] == 1){
+        usleep(100);
+    }
+    return 0;
+}
+
+int unlock(int thread_id){
+    _lock[(thread_id + 1) % Car_Number] = 0;
+    return 0;
+}
+
+void* func(void* ptr){
+    int car_id = *(int*)ptr;
+    int crosses_counter = 0;
+    //**********CRITICAL SECTION**********//
+    while (crosses_counter < crosses){
+        lock(car_id);
+        while (car_on_bridge == Bridge_Capacity){}
+        printf("Car %d has crossed the bridge\n",car_id);
+        car_on_bridge ++;
+        usleep(10000);
+        car_on_bridge --;
+        printf("Car %d has crossed the bridge\n", car_id);
+        crosses_counter++;
+        unlock(car_id);
+    //**********CRITICAL SECTION**********//
+    }
+    return NULL;
+}
+
+int main(){
+    pthread_t threads[Car_Number];
+    int thread_id[Car_Number];
+
+    for (int i = 0; i < Car_Number; i++){
+        thread_id[i] = i;
+        if (pthread_create(&threads[i],NULL,func,&thread_id[i])!=0){
+            printf("Error creating thread");
+            exit(1);
+        }
+    }
+    for (int i = 0; i < Car_Number; i++){
+        if (pthread_join(threads[i],NULL)!=0){
+            printf("Error joining threads");
+            exit(1);
+        }
+    }
+    printf("All cars have crossed %d times!",crosses);
+    return 0;
+}