Generalise and better factor bit reversal and TMS drawing.

Numeric/BitReverse.hpp

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+//
+//  BitReverse.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 05/01/2023.
+//  Copyright © 2023 Thomas Harte. All rights reserved.
+//
+
+#ifndef BitReverse_hpp
+#define BitReverse_hpp
+
+#include <cstdint>
+
+namespace Numeric {
+
+/// @returns @c source with the order of its bits reversed. E.g. if @c IntT is @c uint8_t then
+/// the reverse of bit pattern abcd efgh is hgfd dcba.
+template <typename IntT> constexpr IntT bit_reverse(IntT source);
+
+// The single-byte specialisation uses a lookup table.
+template<> constexpr uint8_t bit_reverse<uint8_t>(uint8_t source) {
+    struct ReverseTable {
+		static constexpr std::array<uint8_t, 256> reverse_table() {
+			std::array<uint8_t, 256> map{};
+			for(std::size_t c = 0; c < 256; ++c) {
+				map[c] = uint8_t(
+					((c & 0x80) >> 7) |
+					((c & 0x40) >> 5) |
+					((c & 0x20) >> 3) |
+					((c & 0x10) >> 1) |
+					((c & 0x08) << 1) |
+					((c & 0x04) << 3) |
+					((c & 0x02) << 5) |
+					((c & 0x01) << 7)
+				);
+			}
+			return map;
+		}
+    };
+
+	const std::array<uint8_t, 256> map = ReverseTable::reverse_table();
+	return map[source];
+}
+
+// All other versions just call the byte-level reverse the appropriate number of times.
+template <typename IntT> constexpr IntT bit_reverse(IntT source) {
+	IntT result;
+
+	uint8_t *src = reinterpret_cast<uint8_t *>(&source);
+	uint8_t *dest = reinterpret_cast<uint8_t *>(&result) + sizeof(result) - 1;
+	for(size_t c = 0; c < sizeof(source); c++) {
+		*dest = bit_reverse(*src);
+		++src;
+		--dest;
+	}
+
+	return result;
+}
+
+}
+
+#endif /* BitReverse_hpp */