Add message protocol buffer

Makefile

@@ -2,16 +2,27 @@
 # Single lora testing app
 
 CC=g++
-CFLAGS=-c -Wall
-LIBS=-lwiringPi
+CFLAGS=-c -Wall `pkg-config --cflags 'libprotobuf-c >= 1.0.0'`
+LIBS=-lwiringPi -lprotobuf-c
 
 all: dragino_lora_app
 
-dragino_lora_app: main.o
-	$(CC) main.o  $(LIBS) -o dragino_lora_app
+dragino_lora_app: main.o protobuf.o message.pb-c.o
+	$(CC) main.o protobuf.o message.pb-c.o $(LIBS) -o dragino_lora_app
 
-main.o: main.c
+main.o: main.c protobuf.h
 	$(CC) $(CFLAGS) main.c
 
+protobuf.o: message.pb-c.h protobuf.c protobuf.h
+	$(CC) $(CFLAGS) protobuf.c -o protobuf.o
+
+protobuf.h: message.pb-c.h
+
+message.pb-c.o: message.pb-c.h message.pb-c.c
+	$(CC) $(CFLAGS) message.pb-c.c -o message.pb-c.o
+
+message.pb-c.h message.pb-c.c: message.proto
+	protoc-c --c_out=. message.proto
+
 clean:
-	rm *.o dragino_lora_app	
+	rm *.o dragino_lora_app	message.pb-c.c message.pb-c.h

message.proto

@@ -0,0 +1,12 @@
+syntax = "proto2";
+
+package Fenceless;
+
+message Coordinate {
+    required double x = 1;
+    required double y = 2;
+}
+
+message CollarResponse {
+    required Coordinate loc = 1;
+}

protobuf.c

@@ -0,0 +1,32 @@
+#include "message.pb-c.h"
+#include "protobuf.h"
+#include <stdlib.h>
+
+void* _allocator_alloc(void*, size_t count) {
+    return malloc(count);
+}
+
+void _allocator_free(void*, void* data) {
+    free(data);
+}
+
+static ProtobufCAllocator malloc_allocator = {
+    _allocator_alloc, _allocator_free, NULL
+};
+
+void encode_update(double x, double y, uint8_t* buffer) {
+    Fenceless__Coordinate coord;
+    Fenceless__CollarResponse response;
+
+    fenceless__coordinate__init(&coord);
+    coord.x = x;
+    coord.y = y;
+
+    fenceless__collar_response__init(&response);
+    response.loc = &coord;
+    fenceless__collar_response__pack(&response, buffer);
+}
+
+Fenceless__CollarResponse* decode_update(size_t len, uint8_t* buffer) {
+    return fenceless__collar_response__unpack(&malloc_allocator, len, buffer);
+}

protobuf.h

@@ -0,0 +1,4 @@
+#include "message.pb-c.h"
+
+void encode_update(double x, double y, uint8_t* buffer);
+Fenceless__CollarResponse* decode_update(size_t len, uint8_t* buffer);