Clean up backend detection flow.

common.h

@@ -1,12 +1,8 @@
+#include <stdbool.h>
 #include <stdint.h>
 #include <unistd.h>
 
 
-//////// misc
-
-#define PARSER_STATE_LEN 256
-
-
 //////// buf
 
 #define BUF_LEN_MAX 256
@@ -15,6 +11,10 @@ struct buf {
 	size_t start;
 	size_t length;
 };
+#define BUF_INIT { \
+	.start = 0, \
+	.length = 0, \
+}
 
 #define buf_chr(buff, at) ((buff)->buf[(buff)->start + (at)])
 #define buf_at(buff, at) (&buf_chr(buff, at))
@@ -40,6 +40,23 @@ struct packet {
 };
 
 
+//////// backend
+
+#define PARSER_STATE_LEN 256
+struct backend;
+typedef bool (*parser)(struct backend *, struct packet *);
+struct backend {
+	struct buf buf;
+	char parser_state[PARSER_STATE_LEN];
+	parser parser;
+};
+#define BACKEND_INIT { \
+	.buf = BUF_INIT, \
+	.parser_state = { 0 }, \
+	.parser = backend_autodetect_parse, \
+}
+
+
 //////// hex
 void hex_init();
 void hex_to_bin(char *, char *, size_t);