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src/runtime/LockStep.hpp

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+#pragma once
+
+#include <chrono>
+#include <thread>
+#include <print>
+
+namespace tw {
+
+/**
+ * Controls thread sleep to run exactly `n` times per second
+ */
+class LockStep {
+    using Clock = std::chrono::steady_clock;
+    using Millis = std::chrono::microseconds;
+    const uint64_t IN_SECOND = std::chrono::duration_cast<Millis>(std::chrono::seconds(1)).count();
+
+    uint64_t milliseconds;
+
+    std::chrono::time_point<Clock> m_last_point;
+
+    uint64_t m_last_interval_ms;
+
+    bool m_popped;
+
+public:
+    LockStep(uint32_t steps_per_second) {
+        m_last_point = Clock::now();
+        set_steps_per_second(steps_per_second);
+    }
+
+    inline uint64_t milliseconds_per_frame() const {
+        return milliseconds;
+    }
+
+    inline void set_steps_per_second(uint32_t steps_per_second) {
+        milliseconds = IN_SECOND / steps_per_second;
+    }
+
+    inline uint64_t wait_time_in_ms() {
+        return m_last_interval_ms;
+    }
+
+    inline uint64_t fps() {
+        if(m_last_interval_ms == 0) {
+            return IN_SECOND;
+        }
+        return IN_SECOND / m_last_interval_ms;
+    }
+
+    inline double delta_time() const {
+        return m_last_interval_ms / (double)IN_SECOND;
+    }
+
+    bool update() {
+        auto now = Clock::now();
+
+        m_last_interval_ms = duration_cast<Millis>(now - m_last_point).count();
+
+        if(m_last_interval_ms >= milliseconds) {
+            m_last_point = now;
+            return true;
+        }
+
+        return false;
+    }
+    
+    /**
+     * Waits if time interval from previous call is less than time between two steps
+     */
+    bool wait_for_next_step() {
+        auto now = Clock::now();
+
+        m_last_interval_ms = duration_cast<Millis>(now - m_last_point).count();
+
+        if(m_last_interval_ms < milliseconds) {
+            std::this_thread::sleep_for(Millis(milliseconds - m_last_interval_ms));
+            return true;
+        }
+
+        m_last_point = now;
+        return false;
+    }
+};
+
+}