diff -r aa7dc7faf1bb -r 358a601bfe81 MessageCodec.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MessageCodec.cpp	Sun May 11 00:30:03 2025 +0200
@@ -0,0 +1,118 @@
+/**
+ * djm-fix
+ * Copyright © 2025 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <iostream>
+#include <iomanip>
+
+#include "MessageCodec.h"
+
+Message MessageCodec::decode(std::vector<uint8_t> data) {
+	using ERR = std::invalid_argument;
+
+	if (data.empty() || data.front() != 0xf0 || data.back() != 0xf7)
+		throw ERR("not a MIDI SysEx message");
+
+	// Manufacturer MIDI SysEx ID Numbers:
+	//   00H 40H 05H = AlphaTheta Corporation
+	//   00H 40H 06H = Pioneer Corporation
+	if (data.size() < 4
+			|| data[1] != 0x00
+			|| data[2] != 0x40
+			|| data[3] != 0x05)
+		throw ERR("wrong message Manufacturer MIDI SysEx ID");
+
+	if (data.size() < 8) throw ERR("missing message version");
+
+	uint8_t msgVersion = data[7];
+
+	if (data.size() < 10) throw ERR("missing message type");
+
+	MessageType msgType;
+	if /**/ (data[9] == 0x11) msgType = MessageType::D11_GREETING;
+	else if (data[9] == 0x12) msgType = MessageType::H12_SEED1;
+	else if (data[9] == 0x13) msgType = MessageType::D13_HASH1_SEED2;
+	else if (data[9] == 0x14) msgType = MessageType::H14_HASH2;
+	else if (data[9] == 0x15) msgType = MessageType::D15_CONFIRMATION;
+	else throw ERR("unsupported message type");
+
+	if (data.size() < 11) throw ERR("missing message length");
+	if (data[10] != data.size() - 10) throw ERR("wrong message length");
+
+	std::vector<Field> fields;
+
+	for (size_t start = 11; data.size() > start + 1;) {
+		FieldType fieldType;
+		if /**/ (data[start] == 0x01) fieldType = FieldType::F01;
+		else if (data[start] == 0x02) fieldType = FieldType::F02;
+		else if (data[start] == 0x03) fieldType = FieldType::F03;
+		else if (data[start] == 0x04) fieldType = FieldType::F04;
+		else if (data[start] == 0x05) fieldType = FieldType::F05;
+		else throw ERR("unsupported field type");
+
+		size_t fieldSize = data[start + 1];
+
+		if (data.size() < start + fieldSize + 1) throw ERR("field overflow");
+		//                                    ^ 0xf7 messsage end
+
+		std::vector<uint8_t> fieldData(
+				data.begin() + start + 2,
+				data.begin() + start + fieldSize);
+
+		fields.push_back({fieldType, fieldData});
+
+		start += fieldSize;
+	}
+
+	return Message(msgType, msgVersion, fields);
+}
+
+std::vector<uint8_t> MessageCodec::encode(Message msg) {
+	using ERR = std::invalid_argument;
+
+	std::vector<uint8_t> data;
+
+	data.push_back(0xf0);
+
+	data.push_back(0x00);
+	data.push_back(0x40);
+	data.push_back(0x05);
+
+	data.push_back(0x00);
+	data.push_back(0x00);
+	data.push_back(0x00);
+
+	data.push_back(msg.version);
+	data.push_back(0x00);
+	data.push_back((uint8_t) msg.type);
+
+	uint8_t msgLength = 2; // 2 = type + lenght
+	for (const auto& field : msg.fields) msgLength += field.data.size() + 2;
+
+	data.push_back(msgLength);
+
+	for (const auto& field : msg.fields) {
+		size_t fieldSize = field.data.size() + 2;
+		if (fieldSize > 256) throw ERR("message field too long");
+		data.push_back((uint8_t) field.type);
+		data.push_back((uint8_t) (fieldSize));
+		data.insert(data.end(), field.data.begin(), field.data.end());
+	}
+
+	data.push_back(0xf7);
+
+	return data;
+}