1 files changed, 29 insertions, 0 deletions
diff --git a/lib/nes/common/fps-counter.cc b/lib/nes/common/fps-counter.cc
new file mode 100644
index 0000000..ef6169b
--- /dev/null
+++ b/lib/nes/common/fps-counter.cc
@@ -0,0 +1,29 @@
+#include "nes/common/fps-counter.hh"
+
+namespace nes
+{
+	auto fps_counter::frame(std::chrono::microseconds const elapsed_time) -> void
+	{
+		if (elapsed_time.count() <= 0) { return; }
+
+		if (buffer_position_ == 0)
+		{
+			// Update fps count.
+			auto sum = u32{ 0 };
+			for (auto i = u32{ 0 }; i < buffer_size; ++i) { sum += frame_times_[i]; }
+			if (sum > 0)
+			{
+				buffered_fps_ = (buffer_size * 1000000) / sum;
+			}
+			else
+			{
+				buffered_fps_ = 0;
+			}
+		}
+
+		// Add the frame time to the buffer, replacing any existing content in the ring buffer.
+		auto const frame_time = static_cast<u32>(elapsed_time.count());
+		frame_times_[buffer_position_] = frame_time;
+		buffer_position_ = (buffer_position_ + 1) % buffer_size;
+	}
+} // namespace nes
+\ No newline at end of file