//
// UART 外设实现
// 基于 UART 规格,包含完整的 FIFO、中断和调制解调器控制功能
//

using System;
using System.Collections.Generic;
using Antmicro.Renode.Core;
using Antmicro.Renode.Logging;
using Antmicro.Renode.Peripherals.Bus;
using Antmicro.Renode.Peripherals.UART;
using Antmicro.Renode.Utilities;
using Antmicro.Renode.Time;

namespace Antmicro.Renode.Peripherals.CustomPeripherals
{
    /// <summary>
    /// 毫秒计数器
    /// </summary>
    public class Custom_MS : IDoubleWordPeripheral, IKnownSize
    {
        private readonly IMachine machine;        

        public Custom_MS(IMachine machine)    
        {
            this.machine = machine;    

            // 初始化寄存器
            DefineRegisters();
            Reset();

            this.Log(LogLevel.Info, "Custom_MS initialized");

            // 启动后台计时任务
            // StartCountingTask();

        }

        public void Reset()
        {

            ms_cnt = 0;        // 毫秒计数
            rstr = 0x00;        // 复位/使能寄存器
            startTime = machine.ElapsedVirtualTime;     //记录启动时间

            this.Log(LogLevel.Info, "Custom_MS reset, startTime={0}", startTime.TimeElapsed);       
        }


        void get_msCnt()
        {
            TimeStamp currentTime = machine.ElapsedVirtualTime;
            TimeInterval timeDifference = currentTime.TimeElapsed - startTime.TimeElapsed;

            double timeDiffMs = timeDifference.TotalMilliseconds;
            // ms_cnt = (ushort)(timeDiffMs % 1000);
            ms_cnt = (ushort)timeDiffMs;
            this.Log(LogLevel.Info, "Custom_MS currentTime={0}", currentTime.TimeElapsed); 
            this.Log(LogLevel.Info, "Custom_MS timeDiffMs={0}", timeDiffMs); 
        }
        
        private void DefineRegisters()
        {
            // 寄存器访问通过 ReadDoubleWord/WriteDoubleWord 实现

        }


        // ========================================
        // IBusPeripheral 接口实现
        // ========================================
        public uint ReadDoubleWord(long offset)
        {
            return ReadRegisters(offset);
        }

        public void WriteDoubleWord(long offset, uint value)
        {
            WriteRegisters(offset, value);
        }


        // ========================================
        // 自定义
        // ========================================
        public uint ReadRegisters(long offset)
        {
            uint value = 0;

            switch (offset)
            {
                case (long)Registers.CNT_REG:      // 毫秒延迟计时
                    get_msCnt();
                    value = (uint)ms_cnt;
                    this.Log(LogLevel.Info, "Read CNT_REG: {0}", value);
                    break;

                case (long)Registers.RSTR_REG:      // 复位/使能,暂无读操作
                    value = (uint)(rstr & 0xFF);
                    this.Log(LogLevel.Info, "Read RSTR_REG: 0x{0}", value);
                    break;

                default:
                    this.Log(LogLevel.Warning, "Read to unknown offset: 0x{0:X}", offset);
                    break;
            }
            
            return value;
        }


        public void WriteRegisters(long offset, uint value)
        {

            switch (offset)
            {

                case (long)Registers.RSTR_REG:      // 复位/使能,暂无读操作
                    rstr = (byte)(value & 0xFF);
                    this.Log(LogLevel.Info, "Write RSTR_REG: 0x{0:X2}", rstr);
                    if ((rstr & 0XFF) == RSTR_RES)
                    {
                        Reset();
                    }
                    break;

                default:
                    this.Log(LogLevel.Warning, "Write to unknown offset: 0x{0:X}", offset);
                    break;
            }
        }


        public long Size => 0x80;   //uart地址长度总空间


        // ========================================
        // 寄存器定义
        // ========================================

        private enum Registers : long
        {
            CNT_REG = 0x00,          // 毫秒延迟计时
            RSTR_REG = 0x7C            // 复位/使能 0x55复位清零；其他使能
        }

        

        // RSTR 复位/使能寄存器
        private const byte RSTR_RES = 0x55;  // 0x55复位清零，其他使能


        // ========================================
        // 私有字段
        // ========================================
        private TimeStamp startTime;  // 记录累加器启动时间

        // 寄存器
        private ushort ms_cnt;        // FIFO状态寄存器
        private byte rstr;          // 复位/使能
        
    }
}