BatteryStatusArray

数据结构

字节索引	类型	字段含义
0-1	uint16	电池数量
2-3	uint16	保留字段，必须为 0
4-...	BatteryStatus 数组	电池状态数组，按顺序连续存放

单个 BatteryStatus 是变长结构，因此数组不能按固定步长随机访问，需要从第一个元素开始按每个元素的 temp_count 顺序解析。总长度为 $4 + \sum_{i=0}^{battery\_count-1}(20 + temp\_count_i \times 4)$ 字节

示例

C++ 示例

struct BatteryStatusArrayHeader {
  uint16_t battery_count;
  uint16_t reserved;
};

struct BatteryStatusHeader {
  uint32_t fault_code;
  float voltage;
  float current;
  float soc;
  uint16_t temp_count;
  uint16_t reserved;
};

// payload = BatteryStatusArrayHeader + battery_count * variable-length BatteryStatus

Rust 示例

#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct BatteryStatusArrayHeader {
    pub battery_count: u16,
    pub reserved: u16,
}

#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct BatteryStatusHeader {
    pub fault_code: u32,
    pub voltage: f32,
    pub current: f32,
    pub soc: f32,
    pub temp_count: u16,
    pub reserved: u16,
}

const _: () = {
    assert!(core::mem::size_of::<BatteryStatusArrayHeader>() == 4);
    assert!(core::mem::size_of::<BatteryStatusHeader>() == 20);
};

Dart 示例

import 'dart:typed_data';

final class BatteryStatusArrayView {
  static const int headerLength = 4;
  static const int batteryStatusHeaderLength = 20;
  static const int tempLength = Float32List.bytesPerElement;

  final ByteBuffer buffer;
  final ByteData header;
  final int offsetInBytes;

  BatteryStatusArrayView(this.buffer, [this.offsetInBytes = 0])
      : header = ByteData.view(buffer, offsetInBytes, headerLength);

  int get batteryCount => header.getUint16(0, Endian.little);

  int batteryStatusOffset(int index) {
    var currentOffset = offsetInBytes + headerLength;
    for (var i = 0; i < index; i++) {
      final data = ByteData.view(buffer, currentOffset, batteryStatusHeaderLength);
      final tempCount = data.getUint16(16, Endian.little);
      currentOffset += batteryStatusHeaderLength + tempCount * tempLength;
    }
    return currentOffset;
  }
}

Java 示例

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public final class BatteryStatusArrayView {
  public static final int HEADER_LENGTH = 4;
  public static final int BATTERY_STATUS_HEADER_LENGTH = 20;
  public static final int TEMP_LENGTH = Float.BYTES;

  private final ByteBuffer buffer;
  private final int offset;

  public BatteryStatusArrayView(ByteBuffer buffer, int offset) {
    this.buffer = buffer.order(ByteOrder.LITTLE_ENDIAN);
    this.offset = offset;
  }

  public int batteryCount() { return Short.toUnsignedInt(buffer.getShort(offset)); }

  public int batteryStatusOffset(int index) {
    int currentOffset = offset + HEADER_LENGTH;
    for (int i = 0; i < index; i++) {
      int tempCount = Short.toUnsignedInt(buffer.getShort(currentOffset + 16));
      currentOffset += BATTERY_STATUS_HEADER_LENGTH + tempCount * TEMP_LENGTH;
    }
    return currentOffset;
  }
}