CommonFuncs: Generify rotation functions and move them to BitUtils.h

These are bit manipulation functions, so they belong within BitUtils.

This also gets rid of duplicated code and avoids relying on compiler
reserved names existing or not existing to determine whether or not we
define a set of functions.

Optimizers are smart enough in GCC and clang to transform the code to a
ROR or ROL instruction in the respective functions.

Source/Core/Common/BitUtils.h

@@ -100,6 +100,50 @@ constexpr Result ExtractBits(const T src) noexcept
   return ExtractBits<T, Result>(src, begin, end);
 }
 
+///
+/// Rotates a value left (ROL).
+///
+/// @param  value  The value to rotate.
+/// @param  amount The number of bits to rotate the value.
+/// @tparam T      An unsigned type.
+///
+/// @return The rotated value.
+///
+template <typename T>
+constexpr T RotateLeft(const T value, size_t amount) noexcept
+{
+  static_assert(std::is_unsigned<T>(), "Can only rotate unsigned types left.");
+
+  amount %= BitSize<T>();
+
+  if (amount == 0)
+    return value;
+
+  return static_cast<T>((value << amount) | (value >> (BitSize<T>() - amount)));
+}
+
+///
+/// Rotates a value right (ROR).
+///
+/// @param  value  The value to rotate.
+/// @param  amount The number of bits to rotate the value.
+/// @tparam T      An unsigned type.
+///
+/// @return The rotated value.
+///
+template <typename T>
+constexpr T RotateRight(const T value, size_t amount) noexcept
+{
+  static_assert(std::is_unsigned<T>(), "Can only rotate unsigned types right.");
+
+  amount %= BitSize<T>();
+
+  if (amount == 0)
+    return value;
+
+  return static_cast<T>((value >> amount) | (value << (BitSize<T>() - amount)));
+}
+
 ///
 /// Verifies whether the supplied value is a valid bit mask of the form 0b00...0011...11.
 /// Both edge cases of all zeros and all ones are considered valid masks, too.