+struct Thread;
+
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
+
+#if !defined(NO_SPINLOCK)
+/// Spinlock class wraps low level atomic operations to provide a spin lock
+
+class Spinlock {
+
+ std::atomic_int lock;
+
+public:
+ Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+ void acquire() {
+ while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+ while (lock.load(std::memory_order_relaxed) <= 0) {}
+ }
+ void release() { lock.store(1, std::memory_order_release); }
+};
+
+#else
+
+class Spinlock {
+
+ std::mutex mutex;
+
+public:
+ void acquire() { mutex.lock(); }
+ void release() { mutex.unlock(); }
+};
+
+#endif
+
+/// SplitPoint struct stores information shared by the threads searching in
+/// parallel below the same split point. It is populated at splitting time.