Fix DMP encoder/decoder

lib/main.dart

@@ -66,7 +66,7 @@ class _MyHomePageState extends State<MyHomePage> {
   // Services
   late final DeviceCommunicationService _deviceService;
   late final NetworkService _networkService;
-  late final DataProcessingService _dataService;
+  late final DmpDecoderService _dmpDecoder;
   late final FileService _fileService;
   late final FirmwareUpdateService _firmwareService;
 
@@ -176,7 +176,7 @@ class _MyHomePageState extends State<MyHomePage> {
     // Initialize services
     _deviceService = DeviceCommunicationService();
     _networkService = NetworkService();
-    _dataService = DataProcessingService();
+    _dmpDecoder = DmpDecoderService();
     _fileService = FileService();
     _firmwareService = FirmwareUpdateService(_deviceService);
 
@@ -301,7 +301,7 @@ class _MyHomePageState extends State<MyHomePage> {
     for (final fileResult in successfulFiles) {
       if (fileResult.hasData) {
         transferBuffer = fileResult.data!;
-        final dataResult = await _dataService.processTransferBuffer(transferBuffer, unitType);
+        final dataResult = await _dmpDecoder.processTransferBuffer(transferBuffer, unitType);
 
         if (dataResult.success) {
           setState(() {
@@ -375,7 +375,7 @@ class _MyHomePageState extends State<MyHomePage> {
   }
 
   Future<void> _analyzeTransferBuffer() async {
-    final result = await _dataService.processTransferBuffer(transferBuffer, unitType);
+    final result = await _dmpDecoder.processTransferBuffer(transferBuffer, unitType);
 
     if (result.success) {
       setState(() {
@@ -533,7 +533,48 @@ class _MyHomePageState extends State<MyHomePage> {
 
   // Export handlers
   Future<void> _onSaveDMP() async {
-    await _handleExportOperation(() => _fileService.saveDMPFileFromSections(sections, unitType));
+    try {
+      final result = await _fileService.saveDMPFileFromSections(sections, unitType);
+
+      if (result.needsChoice && result.versionAnalysis != null && mounted) {
+        // Show dialog for mixed version handling
+        final choice = await MixedVersionDialog.show(context, result.versionAnalysis!);
+
+        if (choice == MixedVersionChoice.cancel) {
+          return;
+        }
+
+        // Get file path
+        final filePath = await _fileService.getSaveFilePathPublic("DMP", "dmp");
+        if (filePath == null) {
+          return;
+        }
+
+        FileResult finalResult;
+        if (choice == MixedVersionChoice.separate) {
+          finalResult = await _fileService.saveDMPFileSeparate(result.versionAnalysis!, filePath);
+        } else {
+          finalResult = await _fileService.saveDMPFileAsV6(sections.selectedSections, filePath);
+        }
+
+        if (finalResult.success && mounted) {
+          _showMessage(finalResult.message ?? 'Export completed successfully');
+        } else if (!finalResult.success && mounted) {
+          _showErrorMessage(finalResult.error ?? 'Export failed');
+        }
+      } else {
+        // Normal result handling
+        if (result.success && mounted) {
+          _showMessage(result.message ?? 'Export completed successfully');
+        } else if (!result.success && mounted) {
+          _showErrorMessage(result.error ?? 'Export failed');
+        }
+      }
+    } catch (e) {
+      if (mounted) {
+        _showErrorMessage('Export failed: $e');
+      }
+    }
   }
 
   Future<void> _onExportXLS() async {

lib/models/dmp_constants.dart

@@ -0,0 +1,120 @@
+/// DMP (Data Memory Package) file format constants
+///
+/// These constants define the binary structure of MNemo v2 DMP files.
+/// See: doc/MNemo DMP File Format - Complete Documentation.md
+class DmpConstants {
+  // Private constructor to prevent instantiation
+  DmpConstants._();
+
+  // ============================================================================
+  // FILE VERSION MAGIC BYTES (Version 5+)
+  // ============================================================================
+
+  /// Magic byte A for file version header (version 5+)
+  static const int fileVersionMagicA = 68; // 0x44
+
+  /// Magic byte B for file version header (version 5+)
+  static const int fileVersionMagicB = 89; // 0x59
+
+  /// Magic byte C for file version header (version 5+)
+  static const int fileVersionMagicC = 101; // 0x65
+
+  // ============================================================================
+  // SHOT RECORD MAGIC BYTES (Version 5+)
+  // ============================================================================
+
+  /// Magic byte A for shot record start (version 5+)
+  static const int shotStartMagicA = 57; // 0x39
+
+  /// Magic byte B for shot record start (version 5+)
+  static const int shotStartMagicB = 67; // 0x43
+
+  /// Magic byte C for shot record start (version 5+)
+  static const int shotStartMagicC = 77; // 0x4D
+
+  /// Magic byte A for shot record end (version 5+)
+  static const int shotEndMagicA = 95; // 0x5F
+
+  /// Magic byte B for shot record end (version 5+)
+  static const int shotEndMagicB = 25; // 0x19
+
+  /// Magic byte C for shot record end (version 5+)
+  static const int shotEndMagicC = 35; // 0x23
+
+  // ============================================================================
+  // LIDAR DATA MAGIC BYTES (Version 6)
+  // ============================================================================
+
+  /// Magic byte A for Lidar data block start (version 6)
+  static const int lidarStartMagicA = 32; // 0x20 - VOLSTART_VALA
+
+  /// Magic byte B for Lidar data block start (version 6)
+  static const int lidarStartMagicB = 33; // 0x21 - VOLSTART_VALB
+
+  /// Magic byte C for Lidar data block start (version 6)
+  static const int lidarStartMagicC = 34; // 0x22 - VOLSTART_VALC
+
+  // ============================================================================
+  // FORMAT VERSION LIMITS
+  // ============================================================================
+
+  /// Minimum supported DMP file version
+  static const int minSupportedVersion = 2;
+
+  /// Maximum supported DMP file version
+  static const int maxSupportedVersion = 6;
+
+  /// First version with magic byte validation
+  static const int firstVersionWithMagicBytes = 5;
+
+  /// First version with temperature and time data
+  static const int firstVersionWithTemperature = 3;
+
+  /// First version with LRUD passage measurements
+  static const int firstVersionWithLRUD = 4;
+
+  /// First version with optional Lidar data
+  static const int firstVersionWithLidar = 6;
+
+  // ============================================================================
+  // RECORD SIZES
+  // ============================================================================
+
+  /// Size of section header in bytes
+  static const int sectionHeaderSize = 13;
+
+  /// Size of shot record in bytes (v5+, excluding optional Lidar data)
+  static const int shotRecordSize = 35;
+
+  /// Size of each Lidar point in bytes
+  static const int lidarPointSize = 6;
+
+  // ============================================================================
+  // VALIDATION HELPERS
+  // ============================================================================
+
+  /// Check if a version number is valid
+  static bool isValidVersion(int version) {
+    return version >= minSupportedVersion && version <= maxSupportedVersion;
+  }
+
+  /// Check if a version uses magic bytes
+  static bool usesMagicBytes(int version) {
+    return version >= firstVersionWithMagicBytes;
+  }
+
+  /// Check if a version supports temperature data
+  static bool hasTemperature(int version) {
+    return version >= firstVersionWithTemperature;
+  }
+
+  /// Check if a version supports LRUD data
+  static bool hasLRUD(int version) {
+    return version >= firstVersionWithLRUD;
+  }
+
+  /// Check if a version supports Lidar data
+  static bool hasLidar(int version) {
+    return version >= firstVersionWithLidar;
+  }
+}

lib/models/models.dart

@@ -4,4 +4,5 @@ export 'shot.dart';
 export 'section.dart';
 export 'section_list.dart';
 export 'survey_quality.dart';
-export 'lidar_data.dart';
+export 'lidar_data.dart';
+export 'dmp_constants.dart';