#first commit

lib/core/network/protocol_decoder.dart

@@ -0,0 +1,59 @@
+import 'dart:typed_data';
+
+class RawPacket {
+  final int command; // 第三位指令位
+  final Uint8List payload; // 数据位
+  RawPacket({required this.command, required this.payload});
+}
+
+class ProtocolDecoder {
+  static const head = [0xAB, 0xAA];
+  static const tail = [0xAA, 0xAB];
+  final List<int> _buffer = [];
+
+  List<RawPacket> decode(List<int> newData) {
+    _buffer.addAll(newData);
+    List<RawPacket> packets = [];
+
+    while (_buffer.length >= 5) {
+      // 最小包长度：头2+指令1+尾2 = 5，加1位数据=6，但是心跳包是AB AA FF AA AB
+      // 1. 找头
+      int headIdx = -1;
+      for (int i = 0; i < _buffer.length - 1; i++) {
+        if (_buffer[i] == head[0] && _buffer[i + 1] == head[1]) {
+          headIdx = i;
+          break;
+        }
+      }
+
+      if (headIdx == -1) {
+        _buffer.clear(); // 没头，全是垃圾数据
+        break;
+      }
+
+      // 2. 找尾
+      int tailIdx = -1;
+      for (int i = headIdx + 2; i < _buffer.length - 1; i++) {
+        if (_buffer[i] == tail[0] && _buffer[i + 1] == tail[1]) {
+          tailIdx = i;
+          break;
+        }
+      }
+
+      if (tailIdx != -1) {
+        // 3. 提取
+        int cmd = _buffer[headIdx + 2];
+        Uint8List payload = Uint8List.fromList(
+          _buffer.sublist(headIdx + 3, tailIdx),
+        );
+        packets.add(RawPacket(command: cmd, payload: payload));
+
+        // 4. 移除已处理部分
+        _buffer.removeRange(0, tailIdx + 2);
+      } else {
+        break; // 还没传完
+      }
+    }
+    return packets;
+  }
+}