Factor out the stuff of being a circular counter.

Numeric/CircularCounter.hpp

@@ -0,0 +1,48 @@
+//
+//  CircularCounter.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 15/02/2026.
+//  Copyright © 2026 Thomas Harte. All rights reserved.
+//
+
+#include <cassert>
+
+namespace Numeric {
+
+template <typename IntT, IntT limit>
+class CircularCounter {
+public:
+	constexpr CircularCounter() noexcept = default;
+	constexpr CircularCounter(const IntT value) noexcept : value_(value) {
+		assert(value < limit);
+	}
+
+	CircularCounter &operator ++() {
+		++value_;
+		if(value_ == limit) {
+			value_ = 0;
+		}
+		return *this;
+	}
+
+	CircularCounter operator ++(int) {
+		const auto result = *this;
+		++*this;
+		return result;
+	}
+
+	operator IntT() const {
+		return value_;
+	}
+
+	CircularCounter &operator = (const IntT rhs) {
+		value_ = rhs;
+		return *this;
+	}
+
+private:
+	IntT value_{};
+};
+
+}