swdc: first segatools added

swdcio/backend.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "swdcio/swdcio.h"
+
+struct swdc_io_backend {
+    void (*get_opbtns)(uint8_t *opbtn);
+    void (*get_gamebtns)(uint16_t *gamebtn);
+    void (*get_analogs)(struct swdc_io_analog_state *state);
+};