bus_traits.h

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#pragma once

 
#include "fl/channels/bus.h"
#include "fl/stl/noexcept.h"
#include "fl/stl/type_traits.h"
 
namespace fl {

template<fl::Bus B, fl::u8 Which = 0> struct BusTraits;

template<fl::Bus B, typename Chipset, fl::u8 Which = 0>
struct BusSupports : fl::false_type {};
 
namespace detail {

template<typename Traits>
inline auto enable_clockless_impl(int) FL_NO_EXCEPT
    -> decltype(Traits::enableClockless(), void()) {
    Traits::enableClockless();
}
template<typename Traits>
inline void enable_clockless_impl(long) FL_NO_EXCEPT {}
template<typename Traits>
inline void enable_clockless() FL_NO_EXCEPT {
    enable_clockless_impl<Traits>(0);
}

template<typename Chipset, typename Traits>
struct enable_clockless_for {
    static void apply() FL_NO_EXCEPT {}
};
template<typename Traits>
struct enable_clockless_for<ClocklessChipset, Traits> {
    static void apply() FL_NO_EXCEPT { enable_clockless<Traits>(); }
};

 
template<Bus B, fl::u8 Which = 0>
inline int bus_register_one() FL_NO_EXCEPT {
    // Explicitly enabling a bus makes it eligible for clockless channels too.
    enable_clockless<BusTraits<B, Which>>();
    BusTraits<B, Which>::registerWithManager();
    return 0;
}
 
}  // namespace detail

template<Bus... Buses>
inline void enableDrivers() FL_NO_EXCEPT {
    // C++11-compatible pack expansion via array initializer trick.
    using expand = int[];
    (void)expand{0, detail::bus_register_one<Buses>()...};
}
 
template<Bus B, fl::u8 Which = 0>
inline void enableDriver() FL_NO_EXCEPT {
    detail::bus_register_one<B, Which>();
}

namespace detail {
 
template<fl::Bus B, fl::u8 Which = 0>
struct BusKeepAliveImpl {
    static inline void odr_use() FL_NO_EXCEPT {
        // ODR-use the singleton accessor's address — sufficient to keep
        // the driver TU alive. We do NOT call `instance()` here because
        // some platforms construct the driver eagerly inside the Meyers
        // singleton and we want `Bus::X`-tagged `addLeds<>` to behave as
        // a pure compile-time annotation (no runtime side effect beyond
        // the linker keep-alive itself).
        (void)&BusTraits<B, Which>::instance;
    }
};
 
template<fl::u8 Which>
struct BusKeepAliveImpl<fl::Bus::AUTO, Which> {
    static inline void odr_use() FL_NO_EXCEPT {}  // AUTO: no pinning, no ODR-use.
};
 
}  // namespace detail
 
template<fl::Bus B, fl::u8 Which = 0>
inline void busKeepAlive() FL_NO_EXCEPT {
    detail::BusKeepAliveImpl<B, Which>::odr_use();
}
 
}  // namespace fl