适配c2;新版设计稿;对战切换手势;主逻辑接通;使用think的阻力值,修改影子模式船位置
This commit is contained in:
1 parent
e6f3e2ecfa
commit
ab653b994f
82 files changed
+25241
-8988
No files matched your search
@@ -9,6 +9,7 @@ namespace Assets.Scripts.Devices.Ant.Interfaces
|
||||
{
|
||||
interface IRowerDevice
|
||||
{
|
||||
C2RowerData c2RowerData { get; }
|
||||
FtmsRowerData rowerData { get; }
|
||||
void Reset();
|
||||
void SetResistanceLevel(ushort v);
|
||||
|
||||
@@ -0,0 +1,82 @@
|
||||
using Assets.Scripts.Ble;
|
||||
using Assets.Scripts.Devices.Ble.Interfaces;
|
||||
using System;
|
||||
using System.Collections.Generic;
|
||||
using System.Linq;
|
||||
using System.Text;
|
||||
using System.Threading.Tasks;
|
||||
using UnityEngine;
|
||||
|
||||
namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
{
|
||||
public class C2RowerData : ICharacteristic, IRowerCommonData
|
||||
{
|
||||
public Guid Uuid => ServiceUuids.Characteristics.C2RowerData;
|
||||
|
||||
public Guid ServiceUuid => ServiceUuids.Characteristics.C2Service;
|
||||
|
||||
public bool IsOptional => false;
|
||||
|
||||
public static event EventHandler EnableChanged;
|
||||
private static bool? _isEnabled;
|
||||
public static bool? IsEnabled
|
||||
{
|
||||
get => _isEnabled;
|
||||
set
|
||||
{
|
||||
_isEnabled = value;
|
||||
if (EnableChanged != null)
|
||||
{
|
||||
EnableChanged(_isEnabled, new EventArgs());
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//0.1 lbs of force, max=6553.5m 单位0.1磅
|
||||
public double PeakDriveForce { get; set; }
|
||||
public double AverageDriveForce { get; set; }
|
||||
|
||||
public event EventHandler PullChanged;
|
||||
private ushort _pullValue;
|
||||
public ushort PullValue
|
||||
{
|
||||
get { return _pullValue; }
|
||||
set
|
||||
{
|
||||
_pullValue = value;
|
||||
if (this.PullChanged != null)
|
||||
{
|
||||
this.PullChanged(this, new EventArgs());
|
||||
}
|
||||
}
|
||||
}
|
||||
public void HandleAttributeReceived(byte[] data)
|
||||
{
|
||||
Debug.Log("数据" + string.Join(",", data));
|
||||
if (data[0] == 53)
|
||||
{
|
||||
PeakDriveForce = LbsToNewton(Convert.ToDouble(BitConvertHelper.ToUInt16(data, 13)) / 10);
|
||||
AverageDriveForce = LbsToNewton(Convert.ToDouble(BitConvertHelper.ToUInt16(data, 15)) / 10);
|
||||
Debug.Log($"峰力值:{PeakDriveForce} 均力值{AverageDriveForce}");
|
||||
}
|
||||
else if (data[0] == 61)
|
||||
{
|
||||
List<ushort> r = new List<ushort>();
|
||||
for (int i = 3; i < data.Length; i += 2)
|
||||
{
|
||||
ushort pull = data[i] < 10 ? (ushort)0 : Convert.ToUInt16(Math.Round(LbsToNewton(data[i])));
|
||||
r.Add(pull);
|
||||
PullValue = pull;
|
||||
}
|
||||
|
||||
Debug.Log("拉力曲线:"+ string.Join(",",r));
|
||||
}
|
||||
}
|
||||
private double LbsToNewton(double lbs) => 4.4482216 * lbs;
|
||||
public void SetUnavailable()
|
||||
{
|
||||
//throw new NotImplementedException();
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
@@ -0,0 +1,11 @@
|
||||
fileFormatVersion: 2
|
||||
guid: 64ae3a6d26480b04c8fed17cc833d179
|
||||
MonoImporter:
|
||||
externalObjects: {}
|
||||
serializedVersion: 2
|
||||
defaultReferences: []
|
||||
executionOrder: 0
|
||||
icon: {instanceID: 0}
|
||||
userData:
|
||||
assetBundleName:
|
||||
assetBundleVariant:
|
||||
@@ -1,4 +1,5 @@
|
||||
using Assets.Scripts.Ble;
|
||||
using Assets.Scripts.Devices.Ant;
|
||||
using Assets.Scripts.Devices.Ble.Interfaces;
|
||||
using System;
|
||||
using System.Collections.Generic;
|
||||
@@ -9,7 +10,7 @@ using UnityEngine;
|
||||
|
||||
namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
{
|
||||
public class FtmsRowerData : ICharacteristic
|
||||
public class FtmsRowerData : ICharacteristic, IRowerCommonData
|
||||
{
|
||||
/// <summary>
|
||||
/// 划桨频率
|
||||
@@ -37,8 +38,26 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
public int InstantaneousPower { get; private set; } = 0;
|
||||
|
||||
public int AveragePower { get; private set; } = 0;
|
||||
|
||||
public int ResistanceLevel { get; private set; } = 0;
|
||||
public static event EventHandler RowerResChanged;
|
||||
private int commonRes = 50;
|
||||
private int thinkRes = 50;
|
||||
|
||||
public int ResistanceLevel
|
||||
{
|
||||
get
|
||||
{
|
||||
var device = App.MainDeviceAdapter.GetDevices().FirstOrDefault(d => (d.State == DeviceState.Connected) && d.Sensor == SensorType.Rower);
|
||||
if (device == null) return 0;
|
||||
if (device.Name.Contains("Think"))
|
||||
{
|
||||
return thinkRes;
|
||||
}
|
||||
else
|
||||
{
|
||||
return commonRes;
|
||||
}
|
||||
}
|
||||
}
|
||||
/// <summary>
|
||||
/// 运行时间
|
||||
/// </summary>
|
||||
@@ -49,6 +68,8 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
public int EnergyPerHour { get; private set; } = 0;
|
||||
|
||||
public int EnergyPerMinute { get; private set; } = 0;
|
||||
public double PeakDriveForce { get; set; } = 0;
|
||||
public double AverageDriveForce { get; set; } = 0;
|
||||
|
||||
public Guid Uuid => ServiceUuids.Characteristics.RowerData;
|
||||
|
||||
@@ -152,7 +173,12 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
}
|
||||
if (this.Flags.HasFlag(RowerDataFlag.ResistanceLevel))
|
||||
{
|
||||
this.ResistanceLevel = BitConvertHelper.ToInt16(data, b);
|
||||
this.commonRes = BitConvertHelper.ToInt16(data, b);
|
||||
var device = App.MainDeviceAdapter.GetDevices().FirstOrDefault(d => (d.State == DeviceState.Connected) && d.Sensor == SensorType.Rower);
|
||||
if (device != null && !device.Name.Contains("Think") && RowerResChanged != null)
|
||||
{
|
||||
RowerResChanged.Invoke(this.commonRes, null);
|
||||
}
|
||||
b += this.SizeOfDataForFlag(RowerDataFlag.ResistanceLevel);
|
||||
}
|
||||
if (this.Flags.HasFlag(RowerDataFlag.ExpendedEnergy))
|
||||
@@ -184,6 +210,16 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
{
|
||||
b += this.SizeOfDataForFlag(RowerDataFlag.RemainingTime);
|
||||
}
|
||||
if (this.Flags.HasFlag(RowerDataFlag.ThinkDragFactor))
|
||||
{
|
||||
this.thinkRes = BitConvertHelper.ToInt16(data, b + 1);
|
||||
var device = App.MainDeviceAdapter.GetDevices().FirstOrDefault(d => (d.State == DeviceState.Connected) && d.Sensor == SensorType.Rower);
|
||||
if (device != null && device.Name.Contains("Think") && RowerResChanged != null)
|
||||
{
|
||||
RowerResChanged.Invoke(this.thinkRes, null);
|
||||
}
|
||||
b += this.SizeOfDataForFlag(RowerDataFlag.ThinkDragFactor);
|
||||
}
|
||||
if (this.Flags.HasFlag(RowerDataFlag.Pull))
|
||||
{
|
||||
List<ushort> list = new List<ushort>();
|
||||
@@ -194,10 +230,24 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
PullValue = val;
|
||||
|
||||
}
|
||||
if (pullList == null) pullList = new List<ushort>();
|
||||
foreach (var pull in list)
|
||||
{
|
||||
if (pull == 0)
|
||||
{
|
||||
if (pullList.Count != 0)
|
||||
{
|
||||
PeakDriveForce = pullList.Max();
|
||||
AverageDriveForce = (double)pullList.Average(x=>x);
|
||||
}
|
||||
pullList.Clear();
|
||||
}
|
||||
pullList.Add(pull);
|
||||
}
|
||||
Debug.Log("拉力:" + string.Join(",",list));
|
||||
}
|
||||
//Debug.Log("原始数据:" + string.Join(",", data));
|
||||
}
|
||||
List<ushort> pullList;
|
||||
public void Reset()
|
||||
{
|
||||
this.StrokeRate = 0;
|
||||
@@ -208,7 +258,9 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
this.AveragePace = 0;
|
||||
this.InstantaneousPower = 0;
|
||||
this.AveragePower = 0;
|
||||
this.ResistanceLevel = 0;
|
||||
this.commonRes = 50;
|
||||
this.thinkRes = 50;
|
||||
//this.ResistanceLevel = 0;
|
||||
this.TotalEnergy = 0;
|
||||
this.EnergyPerHour = 0;
|
||||
this.EnergyPerMinute = 0;
|
||||
@@ -258,6 +310,9 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
case RowerDataFlag.RemainingTime:
|
||||
num = 2;
|
||||
break;
|
||||
case RowerDataFlag.ThinkDragFactor:
|
||||
num = 5;
|
||||
break;
|
||||
default:
|
||||
break;
|
||||
}
|
||||
@@ -288,7 +343,9 @@ namespace Assets.Scripts.Devices.Ble.Characteristic
|
||||
//单周期能耗
|
||||
SingleEnergy = 8192,
|
||||
//拉力曲綫
|
||||
Pull = 16384
|
||||
Pull = 16384,
|
||||
//Think 阻力
|
||||
ThinkDragFactor = 32768
|
||||
}
|
||||
|
||||
|
||||
|
||||
@@ -6,6 +6,7 @@ using System;
|
||||
using System.Collections.Generic;
|
||||
using System.Linq;
|
||||
using System.Text;
|
||||
using System.Threading;
|
||||
using System.Threading.Tasks;
|
||||
using UnityEngine;
|
||||
|
||||
@@ -16,9 +17,12 @@ namespace Assets.Scripts.Devices.Ble.Devices
|
||||
private FtmsRowerData _rowerData;
|
||||
public FtmsRowerData rowerData { get => _rowerData; }
|
||||
|
||||
|
||||
C2RowerData _c2RowerData;
|
||||
public C2RowerData c2RowerData { get => _c2RowerData; }
|
||||
private List<BleServiceInfo> Services;
|
||||
private BleCharacteristicInfo controlPointCharacteristic;
|
||||
private BleCharacteristicInfo c2Control;
|
||||
|
||||
public FtmsRower(BlePeripheralInfo peripheralInfo, IBleWinHwInterface bleWinHwInterface) :base(peripheralInfo, bleWinHwInterface, Ant.SensorType.Rower)
|
||||
{
|
||||
Debug.Log(24);
|
||||
@@ -26,34 +30,50 @@ namespace Assets.Scripts.Devices.Ble.Devices
|
||||
//划船机
|
||||
this._rowerData = new FtmsRowerData();
|
||||
base.Characteristics.Add(rowerData);
|
||||
this._c2RowerData = new C2RowerData();
|
||||
base.Characteristics.Add(c2RowerData);
|
||||
bleWinHwInterface.CharacteristicReadEvent -= CharacteristicReadMainCallback;
|
||||
bleWinHwInterface.CharacteristicReadEvent += CharacteristicReadMainCallback;
|
||||
}
|
||||
|
||||
protected override void CreateServices(List<BleServiceInfo> discoveredServices)
|
||||
{
|
||||
this.Services = discoveredServices;
|
||||
|
||||
Debug.Log("服务+" + string.Join(",", Services.Select(x => x.Id.ToString())));
|
||||
foreach (var service in this.Services)
|
||||
{
|
||||
hwInterface.DiscoverCharacteristic(service, (hwInterface, service1, response) =>
|
||||
{
|
||||
|
||||
foreach (var character in response.Data)
|
||||
{
|
||||
//Debug.Log(character.Id.ToString());
|
||||
if (character.MatchGuid(ServiceUuids.Characteristics.FitnessMachineControlPoint))
|
||||
{
|
||||
Debug.Log("中控台获取");
|
||||
this.controlPointCharacteristic = character;
|
||||
}
|
||||
}
|
||||
else if (character.MatchGuid(ServiceUuids.Characteristics.RowerData))
|
||||
{
|
||||
Debug.Log("划船机");
|
||||
this.hwInterface.SubscribeCharacteristic(character, (hw, cha, res) =>
|
||||
{
|
||||
//Debug.Log("1111111111111111111111");
|
||||
//Debug.WriteLine(res.ToString());
|
||||
var res1 = (res as BleResponse<byte[]>);
|
||||
Debug.Log("收到消息划船机:" + string.Join(",", res1));
|
||||
});
|
||||
Debug.Log("ftms划船机" + service.Id);
|
||||
this.hwInterface.SubscribeCharacteristic(character, null);
|
||||
}
|
||||
else if (character.MatchGuid(ServiceUuids.Characteristics.C2RowerData))
|
||||
{
|
||||
Debug.Log("c2划船机基本数据" + service.Id);
|
||||
//C2RowerData.IsEnabled = true;
|
||||
this.hwInterface.SubscribeCharacteristic(character, null);
|
||||
}
|
||||
else if (character.MatchGuid(ServiceUuids.Characteristics.C2RowerData1))
|
||||
{
|
||||
Debug.Log("c2划船机拉力数据" + service.Id);
|
||||
//C2RowerData.IsEnabled = true;
|
||||
this.hwInterface.SubscribeCharacteristic(character, null);
|
||||
}
|
||||
else if (character.MatchGuid(ServiceUuids.Characteristics.C2RowerControl))
|
||||
{
|
||||
Debug.Log("c2划船机控制台");
|
||||
this.c2Control = character;
|
||||
}
|
||||
}
|
||||
});
|
||||
@@ -62,26 +82,87 @@ namespace Assets.Scripts.Devices.Ble.Devices
|
||||
|
||||
private void CharacteristicReadMainCallback(IBleWinHwInterface hwInterface, BleCharacteristicInfo characteristic, BleResponse<byte[]> response)
|
||||
{
|
||||
foreach (var item in base.Characteristics)
|
||||
|
||||
//var tc = base.Characteristics.SingleOrDefault(x => x.Uuid == ServiceUuids.Characteristics.C2RowerData);
|
||||
//tc.HandleAttributeReceived(new byte[] { 61, 89, 0, 0, 0, 33, 0, 33, 0, 46, 0, 46, 0, 53, 0, 60, 0, 60, 0, 68, 0, 68, 0, 0, 0 });
|
||||
//tc.HandleAttributeReceived(new byte[] { 53, 223, 211, 0, 162, 57, 0, 82, 62, 96, 0, 94, 2, 183, 3, 125, 2, 208, 7, 203, 0 });
|
||||
if (characteristic.MatchGuid(ServiceUuids.Characteristics.RowerData))
|
||||
{
|
||||
if (characteristic.MatchGuid(item.Uuid))
|
||||
{
|
||||
//Debug.Log(string.Join(",", response.Data));
|
||||
item.HandleAttributeReceived(response.Data);
|
||||
}
|
||||
var c = base.Characteristics.SingleOrDefault(x => x.Uuid == ServiceUuids.Characteristics.RowerData);
|
||||
c.HandleAttributeReceived(response.Data);
|
||||
}
|
||||
else
|
||||
{
|
||||
var c = base.Characteristics.SingleOrDefault(x => x.Uuid == ServiceUuids.Characteristics.C2RowerData);
|
||||
var data = new byte[] { characteristic.Id.ToByteArray()[0] }.Concat(response.Data).ToArray();
|
||||
c.HandleAttributeReceived(data);
|
||||
}
|
||||
//foreach (var item in base.Characteristics)
|
||||
//{
|
||||
// if (characteristic.MatchGuid(item.Uuid) || characteristic.Id == ServiceUuids.Characteristics.C2RowerData1)
|
||||
// {
|
||||
// if (item.Uuid == ServiceUuids.Characteristics.C2RowerData1)
|
||||
// {
|
||||
// Debug.Log("c2");
|
||||
// var data = new byte[] { item.Uuid.ToByteArray()[0] }.Concat(response.Data).ToArray();
|
||||
// item.HandleAttributeReceived(data);
|
||||
// }
|
||||
// else if (item.Uuid == ServiceUuids.Characteristics.RowerData)
|
||||
// {
|
||||
// Debug.Log("ftms");
|
||||
// item.HandleAttributeReceived(response.Data);
|
||||
// }
|
||||
// }
|
||||
//}
|
||||
}
|
||||
|
||||
public void Reset()
|
||||
{
|
||||
Debug.Log("发送重置命令"+this.controlPointCharacteristic.ToString());
|
||||
hwInterface.WriteCharacteristic(this.controlPointCharacteristic, new byte[] { 0x01 });
|
||||
if (C2RowerData.IsEnabled == true)
|
||||
{
|
||||
//等对csafe协议研究透彻后写
|
||||
//if (this.c2Control != null)
|
||||
//{
|
||||
// Debug.Log("发送重置命令" + this.c2Control.ToString());
|
||||
// hwInterface.WriteCharacteristic(this.c2Control, new byte[] { 0xF1, 0x86, 0x87, 0x01, 0xF2 });
|
||||
// //hwInterface.WriteCharacteristic(this.c2Control, new byte[] { 0xF1, 0x81, 0x81, 0xF2 });
|
||||
//}
|
||||
}
|
||||
else
|
||||
{
|
||||
if (this.controlPointCharacteristic != null)
|
||||
{
|
||||
Debug.Log("发送重置命令" + this.controlPointCharacteristic.ToString());
|
||||
hwInterface.WriteCharacteristic(this.controlPointCharacteristic, new byte[] { 0x01 });
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
public void SetResistanceLevel(ushort v)
|
||||
{
|
||||
var r = new byte[] { 0x04 }.Concat(BitConverter.GetBytes(v)).ToArray();
|
||||
Debug.Log($"设置阻力{v}, {string.Join(",", r)}");
|
||||
hwInterface.WriteCharacteristic(this.controlPointCharacteristic, r);
|
||||
if (C2RowerData.IsEnabled == true)
|
||||
{
|
||||
//等对csafe协议研究透彻后写
|
||||
//if (this.c2Control != null)
|
||||
//{
|
||||
// var data = new byte[] { 0x29 }.Concat(BitConverter.GetBytes(v)).ToArray();
|
||||
// byte checksum = (byte)((byte)(data[0] ^ data[1]) ^ data[2]);
|
||||
// var r = new byte[] { 0xF1 }.Concat(data).Concat(new byte[] { checksum, 0xf2 }) .ToArray();
|
||||
// Debug.Log($"设置阻力{v}, {string.Join(",", r)}");
|
||||
// hwInterface.WriteCharacteristic(this.c2Control, r);
|
||||
//}
|
||||
}
|
||||
else
|
||||
{
|
||||
if (this.controlPointCharacteristic != null)
|
||||
{
|
||||
//特注:81是think专有指令,后期可能需要兼容其他设备
|
||||
var r = new byte[] { 0x81 }.Concat(BitConverter.GetBytes((ushort)(50 + v))).ToArray();
|
||||
Debug.Log($"设置阻力{v}, {string.Join(",", r)}");
|
||||
hwInterface.WriteCharacteristic(this.controlPointCharacteristic, r);
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,16 @@
|
||||
using System;
|
||||
using System.Collections.Generic;
|
||||
using System.Linq;
|
||||
using System.Text;
|
||||
using System.Threading.Tasks;
|
||||
|
||||
namespace Assets.Scripts.Devices.Ble.Interfaces
|
||||
{
|
||||
interface IRowerCommonData
|
||||
{
|
||||
event EventHandler PullChanged;
|
||||
ushort PullValue { get; set; }
|
||||
double PeakDriveForce { get; set; }
|
||||
double AverageDriveForce { get; set; }
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,11 @@
|
||||
fileFormatVersion: 2
|
||||
guid: 7b9b93075aa03cf4587d75a49b2bfaa8
|
||||
MonoImporter:
|
||||
externalObjects: {}
|
||||
serializedVersion: 2
|
||||
defaultReferences: []
|
||||
executionOrder: 0
|
||||
icon: {instanceID: 0}
|
||||
userData:
|
||||
assetBundleName:
|
||||
assetBundleVariant:
|
||||
@@ -367,6 +367,15 @@ namespace Assets.Scripts.Ble
|
||||
public static Guid WahooFitnessSensorMeasurementInput = new Guid("A026E016-0A7D-4AB3-97FA-F1500F9FEB8B");
|
||||
|
||||
public static Guid RowerData = new Guid("00002AD1-0000-1000-8000-00805F9B34FB");
|
||||
|
||||
|
||||
public static Guid C2RowerControl = new Guid("ce060021-43e5-11e4-916c-0800200c9a66");
|
||||
//0x35 有峰力值和均力值
|
||||
public static Guid C2RowerData = new Guid("ce060035-43e5-11e4-916c-0800200c9a66");
|
||||
//拉力曲线
|
||||
public static Guid C2RowerData1 = new Guid("ce06003D-43e5-11e4-916c-0800200c9a66");
|
||||
public static Guid C2Service = new Guid("CE060030-43E5-11E4-916C-0800200C9A66");
|
||||
//ce060030-43e5-11e4-916c-0800200c9a66
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
@@ -230,7 +230,8 @@ namespace Assets.Scripts.Ble
|
||||
{
|
||||
callback?.Invoke(self, info, s);
|
||||
this.callbacks.Remove(info);
|
||||
Debug.Log("连接成功!");
|
||||
Debug.Log("连接成功!"+info.Name);
|
||||
Devices.Ble.Characteristic.C2RowerData.IsEnabled = info.Name.Contains("PM");
|
||||
if (this.callbacks.Any())
|
||||
{
|
||||
this.ConnectPeripheral(this.callbacks.First().Key, this.callbacks.First().Value);
|
||||
@@ -373,8 +374,11 @@ namespace Assets.Scripts.Ble
|
||||
{
|
||||
this.characteristicNotificationCallbacks.Add(characteristic.Peripheral, callback);
|
||||
}
|
||||
BluetoothLEHardwareInterface.Log("SubscribeCharacteristic" + characteristic.Peripheral.Name + characteristic.Service.ToString() + characteristic.Service.ToString());
|
||||
BluetoothLEHardwareInterface.SubscribeCharacteristicWithDeviceAddress(characteristic.Peripheral.Address, characteristic.Service.ToString(), characteristic.Id.ToString(), null, (deviceAddress, characteristric, bytes) =>
|
||||
Debug.Log("SubscribeCharacteristic" + characteristic.Peripheral.Name + characteristic.Service.ToString() + characteristic.Service.ToString());
|
||||
BluetoothLEHardwareInterface.SubscribeCharacteristicWithDeviceAddress(characteristic.Peripheral.Address, characteristic.Service.ToString(), characteristic.Id.ToString(), (a,b)=>
|
||||
{
|
||||
Debug.Log("返回特征值," + a + "," + b);
|
||||
}, (deviceAddress, characteristric, bytes) =>
|
||||
{
|
||||
if (characteristicReadEvent != null)
|
||||
{
|
||||
|
||||
Reference in new issue
Block a user