semaphore.cpp

#include <thread>
#include <mutex>

class semaphore {
public:
        semaphore(unsigned int count) : count_(count) {}
        
        void wait() {
                std::lock_guard<std::mutex> lock(mutex_);
                while (!count_)
                        condition_.wait(mutex_);
                --count_;
        }
        
        void signal() {
                std::lock_guard<std::mutex> lock(mutex_);
                ++count_;
                condition_.notify_one();
        }
private:
        std::mutex mutex_;
        std::condition_variable condition_;
        unsigned int count_;
};