// Test-fixture application for the pureboot protocol test: prints "APP" on
// the chip's serial link (the same link the loader uses) and idles — the
// proof that the loader's hand-over, and on the tinies the host's
// reset-vector surgery, actually launched it. Linked normally (crt, vectors
// at 0); on the tinies its reset vector is the rjmp the host re-homes.
#include <libavr/libavr.hpp>

using namespace avr::literals;

namespace {

consteval avr::hertz_t clock()
{
	if (avr::hw::db.name == "ATtiny13A")
		return 9.6_MHz;
	if (avr::hw::db.name == "ATtiny85")
		return 8_MHz;
	return 16_MHz;
}

using dev = avr::device<{.clock = clock()}>;

template <avr::hertz_t C, bool Hardware = avr::hw::db.has_reg("UDR0")>
struct link {
	using tx_t = avr::uart::usart0<C, {.baud = 115200_Bd, .max_baud_error = 2.5_pct}>;
	static void tx(char c)
	{
		tx_t::write(static_cast<std::uint8_t>(c));
	}
};

template <avr::hertz_t C>
struct link<C, false> {
	using tx_t = avr::uart::software_tx<C, avr::pb1, 57600_Bd>;
	static void tx(char c)
	{
		tx_t::write(static_cast<std::uint8_t>(c));
	}
};

} // namespace

int main()
{
	avr::init<typename link<dev::clock>::tx_t>();
	link<dev::clock>::tx('A');
	link<dev::clock>::tx('P');
	link<dev::clock>::tx('P');
	while (true) {
	}
}