web_synchronization_tool/lib/windows/little_extension.dart

import 'dart:convert';
import 'dart:typed_data';

/// 添加小端序头
extension MapLittle on Map {

  /// 在转成 Uint8List 的数据前面添加 小端序
  Uint8List toLittle({dynamic value = 0, int length = 4}){

    /// map 转 json
    String mapJson = jsonEncode(this);
    /// json 转 Uint8List
    final mapData = utf8.encode(mapJson);

    /// 添加小端序
    final data = mapData.toLittle(value: value,length: length);

    return data;
  }

}


extension ListIntLittle on List<int> {

  List<int> toLittle({int? value, int length = 4}){

    List<int> ret = [];
    /// 初始化 定义数据长度
    final little = ByteData(4);
    /// 设置小端序数据
    little.setInt32(0, value ?? this.length, Endian.little);

    for (int i = 0; i < little.lengthInBytes; i++) {
      ret.add(little.getUint8(i));
    }

    ret.addAll(this);

    return ret;
  }


}



extension Uint8ListLittle on Uint8List {

  /// 在转成 Uint8List 的数据前面添加 小端序
  Uint8List toLittle({dynamic value = 0, int length = 4}){

    var mapData = this;

    /// 初始化 定义数据长度
    final little = ByteData(length);
    /// 设置小端序数据
    little.setInt32(0, value,Endian.little);
    /// 小端序 转 Uint8List
    var littleData = little.buffer.asUint8List();

    /// 初始化 Uint8List
    Uint8List data = Uint8List(littleData.length + mapData.length );

    /// 组装 map Uint8List 和 小端序 Uint8List
    data.setRange(0, littleData.length, littleData);
    data.setRange(littleData.length, mapData.length + littleData.length, mapData);

    /// 返回组合数据
    return data;
  }

  // Uint8List转int 从前4位转小端序
  int? fromLittle({int start = 0,int length  = 4}) {
    if (this.length < length){
      print('转小端序的数据长度不足');
      return null;
    }

    final littleData = sublist(start,start + length);
    // 创建ByteData
    ByteData byteData = littleData.buffer.asByteData();

    // 读取小端序的32位整数
    int little = byteData.getInt32(0, Endian.little);

    return little;
  }



}