Sketched out a template for clock-receiving components to allow them to be implemented in terms of either half or whole cycles.

Components/ClockReceiver.hpp

@@ -0,0 +1,55 @@
+//
+//  ClockReceiver.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 22/07/2017.
+//  Copyright © 2017 Thomas Harte. All rights reserved.
+//
+
+#ifndef ClockReceiver_hpp
+#define ClockReceiver_hpp
+
+/*! Describes an integer number of whole cycles — pairs of clock signal transitions. */
+class Cycles {
+	public:
+		Cycles(int l) : length_(l) {}
+		operator int() const { return length_; }
+
+	private:
+		int length_;
+};
+
+/*! Describes an integer number of half cycles — single clock signal transitions. */
+class HalfCycles {
+	public:
+		HalfCycles(int l) : length_(l) {}
+		HalfCycles(const Cycles &cycles) : length_(int(cycles) << 1) {}
+		operator int() const { return length_; }
+
+	private:
+		int length_;
+};
+
+/*!
+	ClockReceiver is a template for components that receove a clock, measured either
+	in cycles or in half cycles. They are expected to implement either of the run_for
+	methods; buying into the template means that the other run_for will automatically
+	map appropriately to the implemented one, so callers may use either.
+*/
+template <class T> class ClockReceiver {
+	public:
+		void run_for(const Cycles &cycles) {
+			static_cast<T *>(this)->run_for(HalfCycles(cycles));
+		}
+
+		void run_for(const HalfCycles &half_cycles) {
+			int cycles = int(half_cycles) + half_cycle_carry;
+			half_cycle_carry = cycles & 1;
+			run_for(Cycles(cycles >> 1));
+		}
+
+	private:
+		int half_cycle_carry;
+};
+
+#endif /* ClockReceiver_hpp */

OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj

@@ -563,6 +563,7 @@
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+		4B4EA7E01F24349400C216B4 /* ClockReceiver.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = ClockReceiver.hpp; sourceTree = "<group>"; };
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@@ -1988,6 +1989,7 @@
 		4BC9DF4A1D04691600F44158 /* Components */ = {
 			isa = PBXGroup;
 			children = (
+				4B4EA7E01F24349400C216B4 /* ClockReceiver.hpp */,
 				4BD468F81D8DF4290084958B /* 1770 */,
 				4BC9DF4B1D04691600F44158 /* 6522 */,
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