Add small blink example as bootloader payload test

blink/bootloader.cpp

@@ -0,0 +1,46 @@
+#include "bootloader.hpp"
+
+#include <avr/io.h>
+#include <avr/pgmspace.h>
+#include <avr/wdt.h>
+
+namespace {
+
+typedef void (*jmp_fn)() __attribute__((noreturn));
+
+jmp_fn boot = reinterpret_cast<jmp_fn>(0x0000);
+jmp_fn bootloader = reinterpret_cast<jmp_fn>(0x7800 / 2);
+
+} // namespace
+
+bool Bootloader::handleReset()
+{
+	wdt_reset();
+	uint8_t mcuStatus = MCUSR;
+	MCUSR &= ~(1 << WDRF);
+	wdt_disable();
+	return (mcuStatus & (1 << WDRF));
+}
+
+void Bootloader::reset()
+{
+	wdt_enable(WDTO_15MS);
+	while (true)
+		;
+}
+
+bool Bootloader::check()
+{
+	if (pgm_read_byte(reinterpret_cast<uint16_t>(bootloader) * 2) != 0xFF)
+		return true;
+
+	return false;
+}
+
+void Bootloader::call()
+{
+	if (check())
+		bootloader();
+	else
+		boot();
+}