Implement much of the core Stage2 loader logic for Fusee

fusee/fusee-secondary/src/loader.h

@@ -3,6 +3,22 @@
 
 typedef void (*entrypoint_t)(int argc, void **argv); 
 
+typedef struct {
+    char path[0x300];
+    const char *key;
+    uintptr_t load_address;
+} load_file_t;
+
+typedef struct {
+    entrypoint_t entrypoint;
+} loader_ctx_t;
+
+#define LOADER_ENTRYPOINT_KEY "entrypoint"
+#define LOADER_LOADLIST_KEY "loadlist"
+
+/* TODO: Should we allow files bigger than 16 MB? */
+#define LOADER_FILESIZE_MAX 0x01000000
+
 entrypoint_t load_payload(const char *bct0);
 
 #endif