as5047u_spi_interface.hpp

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#pragma once
#include <cstddef>
#include <cstdint>
#include <type_traits>
#include <utility>
 
namespace as5047u {
 
namespace detail {
 
template <typename Port>
using TransferResult = decltype(std::declval<Port&>().transfer(
    std::declval<const uint8_t*>(), std::declval<uint8_t*>(), std::declval<std::size_t>()));
 
template <typename Port>
inline constexpr bool kTransferReportsStatus =
    std::is_same_v<std::remove_cv_t<std::remove_reference_t<TransferResult<Port>>>, bool>;
 
template <typename Port>
inline bool Transfer(Port& port, const uint8_t* tx, uint8_t* rx, std::size_t len) {
  using Result = TransferResult<Port>;
  static_assert(std::is_void_v<Result> || kTransferReportsStatus<Port>,
                "as5047u: the port's transfer(tx, rx, len) must return bool (true = frame "
                "clocked, false = bus error), or void for a port that never reports errors");
  if constexpr (std::is_void_v<Result>) {
    port.transfer(tx, rx, len);
    return true;
  } else {
    return static_cast<bool>(port.transfer(tx, rx, len));
  }
}
 
} // namespace detail
 
template <typename Derived> class SpiInterface {
public:
  bool transfer(const uint8_t* tx, uint8_t* rx, std::size_t len) {
    return detail::Transfer(*static_cast<Derived*>(this), tx, rx, len);
  }
 
  // Prevent copying
  SpiInterface(const SpiInterface &) = delete;
  SpiInterface &operator=(const SpiInterface &) = delete;
 
protected:
  SpiInterface() = default;
 
  // Allow moving
  SpiInterface(SpiInterface &&) = default;
  SpiInterface &operator=(SpiInterface &&) = default;
 
  ~SpiInterface() = default;
};
 
} // namespace as5047u