From 33f343caf6dfeeda34846ea6705aea3ecfcd30c2 Mon Sep 17 00:00:00 2001
From: xdrm-brackets <xdrm.brackets.dev@gmail.com>
Date: Sun, 2 Dec 2018 21:44:30 +0100
Subject: [PATCH] create 'packet' interface and 'read' from raw uint8_t[]

---
 node/main/packet.cpp | 65 ++++++++++++++++++++++++++++++++++++++++++++
 node/main/packet.h   | 37 +++++++++++++++++++++++++
 2 files changed, 102 insertions(+)
 create mode 100644 node/main/packet.cpp
 create mode 100644 node/main/packet.h

diff --git a/node/main/packet.cpp b/node/main/packet.cpp
new file mode 100644
index 0000000..67869ba
--- /dev/null
+++ b/node/main/packet.cpp
@@ -0,0 +1,65 @@
+#include "packet.h"
+
+
+/* PUBLIC
+----------------------------------------*/
+// builds a packet from raw data and returns the error code
+uint8_t Packet::read(uint8_t buf[], uint8_t size){
+	// 1. fail on invalid size
+	if( size < 1          ) return PKTREAD_EMPTY;
+	if( size > PROTO_SIZE ) return PKTREAD_OVERFLOW;
+
+	// 2. extract packet type
+	type = buf[0] == 0;
+
+	// 3. extract depending on type
+	return type ? read_discover(buf, size) : read_message(buf, size);
+
+};
+
+// writes the binary representation of the packet
+uint8_t Packet::write(uint8_t buf[], uint8_t size){
+	/* TODO */
+	return 0;
+};
+
+
+/* PRIVATE
+----------------------------------------*/
+uint8_t Packet::read_discover(uint8_t buf[], uint8_t size){
+	// 1. fail on invalid size
+	if( size != DISCOVER_SIZE )
+		return PKTREAD_INVALID_DISCOVER_FORMAT;
+
+	// 2. extract fixed
+	dsc.opcode = buf[0];
+	dsc.wave   = buf[1];
+	dsc.dist   = buf[2];
+
+	return PKTREAD_OK;
+};
+
+uint8_t Packet::read_message(uint8_t buf[], uint8_t size){
+	// 1. fail on invalid size
+	if( size < MESSAGE_MIN_SIZE || size > MESSAGE_MAX_SIZE )
+		return PKTREAD_INVALID_MESSAGE_FORMAT;
+
+	// 2. extract fixed
+	msg.opcode = buf[0];
+	msg.dist   = buf[1];
+	msg.ttl    = buf[2];
+	msg.size   = buf[3];
+
+	// 3. check message size
+	if( size - 4 - 1 != msg.size )
+		return PKTREAD_INVALID_MESSAGE_FORMAT;
+
+	// 4. extract message
+	strncpy(
+		(char*) msg.data,
+		(char*)buf+4,
+		msg.size
+	);
+
+	return PKTREAD_OK;
+};
\ No newline at end of file
diff --git a/node/main/packet.h b/node/main/packet.h
new file mode 100644
index 0000000..f15dfc1
--- /dev/null
+++ b/node/main/packet.h
@@ -0,0 +1,37 @@
+#ifndef _PACKET_H_
+	#define _PACKET_H_
+
+	#include "protocol.h"
+	#include <Wire.h>
+
+	#define PKTREAD_OK                      0
+	#define PKTREAD_EMPTY                   1
+	#define PKTREAD_OVERFLOW                2
+	#define PKTREAD_INVALID_DISCOVER_FORMAT 3
+	#define PKTREAD_INVALID_MESSAGE_FORMAT  4
+
+	class Packet {
+		private:
+			// 1. common
+			uint8_t buf[];
+			uint8_t bufsize;
+			bool type; // true = discover ; false = message
+
+			// 2. wrappers
+			struct discover dsc;
+			struct message  msg;
+
+			// 3. helpers
+			uint8_t read_discover(uint8_t buf[], uint8_t size);
+			uint8_t read_message(uint8_t buf[], uint8_t size);
+
+		public:
+			// builds a packet from raw data and returns the status code
+			uint8_t read(uint8_t buf[], uint8_t size);
+
+			// writes the binary representation of the packet
+			uint8_t write(uint8_t buf[], uint8_t size);
+
+	};
+
+#endif
\ No newline at end of file