FCCLite/HengshanPaymentTerminal/StateMachineMessageCutter.cs

using Edge.Core.Processor.Communicator;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HengshanPaymentTerminal
{
    public class StateMachineMessageCutter : IMessageCutter<byte[]>
    {
        #region Internal State enum

        private enum State
        {
            Uninitialized,
            LengthReady,
            BodyReady,
            EtxReady,
            CrcReady
        }

        #endregion

        #region Fields

        public byte[] Message { get; private set; }

        public event EventHandler OnMessageCut;
        public event EventHandler<MessageCutterInvalidMessageReadEventArg> OnInvalidMessageRead;

        private string loggerAppendix = "HengshanPay Terminal";
        private readonly SizableWindow<byte> window;

        //private State nextState = State.Uninitialized;

        private const int STX = 0xFA;

        #endregion

        #region Logger

        static NLog.Logger innerLogger = NLog.LogManager.LoadConfiguration("nlog.config").GetLogger("Communicator");

        #endregion

        public StateMachineMessageCutter()
        {
            window = new SizableWindow<byte>();

            window.OnWindowFull += (data) =>
            {
                byte[] tempBytes = window.ToArray();

                //查找包头位置
                int findIndex = -1;
                for (int index = 0;index < tempBytes.Length - 1;index++)
                {
                    if (tempBytes[index] == STX && tempBytes[index + 1] != STX)
                    {
                        findIndex = index;
                        break;
                    }
                }
                //若没有找到包头，证明目前缓存中都是垃圾数据，清掉
                if (findIndex == -1)
                {
                    window.RemoveRange(0, tempBytes.Length);
                    return;
                }
                //长度不够表示有粘包，部分数据还未接收到，等待下一轮接收数据再处理
                //1byte FA + 1 byte 目标地址 + 1 byte 源地址 + 1 byte 帧号 + 2 byte 有效数据长度 + 2 byte 数据校验 = 8byte
                if(findIndex + 8 > tempBytes.Length)
                {
                    innerLogger.Info($"Insufficient data length，at least ,need {findIndex + 8},but length is {tempBytes.Length}");
                    return;
                }
                //获取有效数据长度
                int dataLen = Bcd2Int(tempBytes[4], tempBytes[5]);
                byte[] reduceFAData = Reduce0xFAPair(tempBytes);
                //去除多余FA后，实际数据不足有效数据长度，表示有粘包，仍非完整数据，等待下一轮接收数据再处理
                if(reduceFAData.Length < dataLen + 2)
                {
                    innerLogger.Info("Insufficient data length");
                    return;
                }
                //计算crc,若值对应不上，表示数据错误
                ushort calculatorValue = HengshanCRC16.ComputeChecksum(reduceFAData.AsSpan(1,reduceFAData.Length - 3).ToArray());
                byte highByte = reduceFAData[reduceFAData.Length - 2];
                byte lowByte = reduceFAData[reduceFAData.Length - 1];
                int crcValue = (highByte << 8) | lowByte;
                if (calculatorValue != crcValue)
                {
                    innerLogger.Info($"crc value error,get value is {crcValue},calculator value is {calculatorValue}");
                    return;
                }

                //获取到实际数据包，并将缓存数据删除
                Message = reduceFAData;
                var safe = OnMessageCut;
                safe?.Invoke(this, null);
                window.RemoveRange(0, tempBytes.Length);
            };
        }

        public void Feed(byte[] data)
        {
            List<byte> list = new(data);
            window.Add(list);
            //for (int i = 0; i < data.Length; i++)
            //{
            //    window.Add(data[i]);
            //}
        }

        private int Get0xFAPairCountInWindow(IEnumerable<byte> data)
        {
            return (int)Math.Round(((double)(data.Count(w => w == 0xFA)) / 2), MidpointRounding.AwayFromZero);
        }

        /// <summary>
        /// 删除多余的FA，在接收到的一个完整数据包中，数据包头为FA，其余数据中每一个FA会替换为两个FA，这里要删除多余的fa来获取实际数据包
        /// </summary>
        /// <param name="data">原数据包</param>
        /// <returns></returns>
        public byte[] Reduce0xFAPair(byte[] data)
        {
            List<byte> list = new();
            for (int index = 0; index < data.Length; index++)
            {
                if (index < data.Length -1 && data[index] == STX && data[index + 1] == STX)
                {
                    list.Add(STX);
                    index++;
                } 
                else
                {
                    list.Add(data[index]);
                }
            }
            return list.ToArray();
        }

        public int Bcd2Int(byte byte1,byte byte2)
        {
            // 提取第一个字节的高四位和低四位  
            int digit1 = (byte1 >> 4) & 0x0F; // 高四位  
            int digit2 = byte1 & 0x0F;        // 低四位  

            // 提取第二个字节的高四位和低四位  
            int digit3 = (byte2 >> 4) & 0x0F; // 高四位  
            int digit4 = byte2 & 0x0F;        // 低四位  

            // 组合成一个整数  
            int result = digit1 * 1000 + digit2 * 100 + digit3 * 10 + digit4;

            return result;
        }
    }
}