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> struct BusTraits;

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

template<Bus B>
inline int bus_register_one() FL_NOEXCEPT {
    BusTraits<B>::registerWithManager();
    return 0;
}
 
}  // namespace detail

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

namespace detail {
 
template<fl::Bus B>
struct BusKeepAliveImpl {
    static inline void odr_use() FL_NOEXCEPT {
        // 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>::instance;
    }
};
 
template<>
struct BusKeepAliveImpl<fl::Bus::AUTO> {
    static inline void odr_use() FL_NOEXCEPT {}  // AUTO: no pinning, no ODR-use.
};
 
}  // namespace detail
 
template<fl::Bus B>
inline void busKeepAlive() FL_NOEXCEPT {
    detail::BusKeepAliveImpl<B>::odr_use();
}
 
}  // namespace fl