Relocated RegisterSizes to Numeric.

Numeric/RegisterSizes.hpp

@@ -0,0 +1,42 @@
+//
+//  RegisterSizes.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 14/05/2017.
+//  Copyright 2017 Thomas Harte. All rights reserved.
+//
+
+#ifndef RegisterSizes_hpp
+#define RegisterSizes_hpp
+
+#include <cstdint>
+
+namespace CPU {
+
+/// Provides a union that — on most compilers for modern consumer architectures,
+/// and therefore this project assumes universally — provides access to the low and
+/// high halves of some larger integer type.
+template <typename Full, typename Half> union RegisterPair {
+	RegisterPair(Full v) : full(v) {}
+	RegisterPair() {}
+
+	Full full;
+#pragma pack(push, 1)
+#if TARGET_RT_BIG_ENDIAN
+	struct {
+		Half high, low;
+	} halves;
+#else
+	struct {
+		Half low, high;
+	} halves;
+#endif
+#pragma pack(pop)
+};
+
+typedef RegisterPair<uint16_t, uint8_t> RegisterPair16;
+typedef RegisterPair<uint32_t, RegisterPair16> RegisterPair32;
+
+}
+
+#endif /* RegisterSizes_hpp */