/*
 
  This Source Code Form is subject to the terms of the Mozilla Public
  License, v. 2.0. If a copy of the MPL was not distributed with this
  file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
  Copyright (C) 2010-2011 Michael Möller <mmoeller@openhardwaremonitor.org>
	
*/

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;

namespace OpenHardwareMonitor.Hardware.CPU {
  internal class GenericCPU : Hardware {

    protected readonly CPUID[][] cpuid;
   
    protected readonly uint family;
    protected readonly uint model;
    protected readonly uint stepping;

    protected readonly int processorIndex;
    protected readonly int coreCount;

    private readonly bool hasModelSpecificRegisters;

    private readonly bool hasTimeStampCounter;
    private readonly bool isInvariantTimeStampCounter;
    private readonly double estimatedTimeStampCounterFrequency;
    private readonly double estimatedTimeStampCounterFrequencyError;

    private ulong lastTimeStampCount;
    private long lastTime;
    private double timeStampCounterFrequency;
    

    private readonly Vendor vendor;

    private readonly CPULoad cpuLoad;
    private readonly Sensor totalLoad;
    private readonly Sensor[] coreLoads;

    protected string CoreString(int i) {
      if (coreCount == 1)
        return "CPU Core";
      else
        return "CPU Core #" + (i + 1);
    }

    public GenericCPU(int processorIndex, CPUID[][] cpuid, ISettings settings)
      : base(cpuid[0][0].Name, CreateIdentifier(cpuid[0][0].Vendor, 
      processorIndex), settings)
    {
      this.cpuid = cpuid;

      this.vendor = cpuid[0][0].Vendor;

      this.family = cpuid[0][0].Family;
      this.model = cpuid[0][0].Model;
      this.stepping = cpuid[0][0].Stepping;

      this.processorIndex = processorIndex;
      this.coreCount = cpuid.Length;  
  
      // check if processor has MSRs
      if (cpuid[0][0].Data.GetLength(0) > 1
        && (cpuid[0][0].Data[1, 3] & 0x20) != 0)
        hasModelSpecificRegisters = true;
      else
        hasModelSpecificRegisters = false;

      // check if processor has a TSC
      if (cpuid[0][0].Data.GetLength(0) > 1
        && (cpuid[0][0].Data[1, 3] & 0x10) != 0)
        hasTimeStampCounter = true;
      else
        hasTimeStampCounter = false;

      // check if processor supports an invariant TSC 
      if (cpuid[0][0].ExtData.GetLength(0) > 7
        && (cpuid[0][0].ExtData[7, 3] & 0x100) != 0)
        isInvariantTimeStampCounter = true;
      else
        isInvariantTimeStampCounter = false;

      if (coreCount > 1)
        totalLoad = new Sensor("CPU Total", 0, SensorType.Load, this, settings);
      else
        totalLoad = null;
      coreLoads = new Sensor[coreCount];
      for (int i = 0; i < coreLoads.Length; i++)
        coreLoads[i] = new Sensor(CoreString(i), i + 1,
          SensorType.Load, this, settings);
      cpuLoad = new CPULoad(cpuid);
      if (cpuLoad.IsAvailable) {
        foreach (Sensor sensor in coreLoads)
          ActivateSensor(sensor);
        if (totalLoad != null)
          ActivateSensor(totalLoad);
      }

      if (hasTimeStampCounter) {
        ulong mask = ThreadAffinity.Set(1UL << cpuid[0][0].Thread);

        EstimateTimeStampCounterFrequency(
          out estimatedTimeStampCounterFrequency, 
          out estimatedTimeStampCounterFrequencyError);  
        
        ThreadAffinity.Set(mask);
      } else {
        estimatedTimeStampCounterFrequency = 0;
      }

      timeStampCounterFrequency = estimatedTimeStampCounterFrequency;                  
    }

    private static Identifier CreateIdentifier(Vendor vendor,
      int processorIndex) 
    {
      string s;
      switch (vendor) {
        case Vendor.AMD: s = "amdcpu"; break;
        case Vendor.Intel: s = "intelcpu"; break;
        default: s = "genericcpu"; break;
      }
      return new Identifier(s,
        processorIndex.ToString(CultureInfo.InvariantCulture));
    }

    private void EstimateTimeStampCounterFrequency(out double frequency, 
      out double error) 
  {     
      double f, e;
      
      // preload the function
      EstimateTimeStampCounterFrequency(0, out f, out e);
      EstimateTimeStampCounterFrequency(0, out f, out e);

      // estimate the frequency
      error = double.MaxValue;
      frequency = 0;
      for (int i = 0; i < 5; i++) {
        EstimateTimeStampCounterFrequency(0.025, out f, out e);
        if (e < error) {
          error = e;
          frequency = f;
        }

        if (error < 1e-4)
          break;
      }                
    }

    private void EstimateTimeStampCounterFrequency(double timeWindow, 
      out double frequency, out double error) 
    {
      long ticks = (long)(timeWindow * Stopwatch.Frequency);
      ulong countBegin, countEnd;

      long timeBegin = Stopwatch.GetTimestamp() +
        (long)Math.Ceiling(0.001 * ticks);
      long timeEnd = timeBegin + ticks;

      while (Stopwatch.GetTimestamp() < timeBegin) { }
      countBegin = Opcode.Rdtsc();
      long afterBegin = Stopwatch.GetTimestamp();

      while (Stopwatch.GetTimestamp() < timeEnd) { }
      countEnd = Opcode.Rdtsc();
      long afterEnd = Stopwatch.GetTimestamp();

      double delta = (timeEnd - timeBegin);
      frequency = 1e-6 * 
        (((double)(countEnd - countBegin)) * Stopwatch.Frequency) / delta;

      double beginError = (afterBegin - timeBegin) / delta;
      double endError = (afterEnd - timeEnd) / delta;
      error = beginError + endError;
    }


    private static void AppendMSRData(StringBuilder r, uint msr, int thread) {
      uint eax, edx;
      if (Ring0.RdmsrTx(msr, out eax, out edx, 1UL << thread)) {
        r.Append(" ");
        r.Append((msr).ToString("X8", CultureInfo.InvariantCulture));
        r.Append("  ");
        r.Append((edx).ToString("X8", CultureInfo.InvariantCulture));
        r.Append("  ");
        r.Append((eax).ToString("X8", CultureInfo.InvariantCulture));
        r.AppendLine();
      }
    }

    protected virtual uint[] GetMSRs() {
      return null;
    }

    public override string GetReport() {
      StringBuilder r = new StringBuilder();

      switch (vendor) {
        case Vendor.AMD: r.AppendLine("AMD CPU"); break;
        case Vendor.Intel: r.AppendLine("Intel CPU"); break;
        default: r.AppendLine("Generic CPU"); break;
      }

      r.AppendLine();
      r.AppendFormat("Name: {0}{1}", name, Environment.NewLine);
      r.AppendFormat("Number of Cores: {0}{1}", coreCount,
        Environment.NewLine);
      r.AppendFormat("Threads per Core: {0}{1}", cpuid[0].Length,
        Environment.NewLine);
      r.AppendLine(string.Format(CultureInfo.InvariantCulture,
        "Timer Frequency: {0} MHz", Stopwatch.Frequency * 1e-6));
      r.AppendLine("Time Stamp Counter: " + (hasTimeStampCounter ? (
        isInvariantTimeStampCounter ? "Invariant" : "Not Invariant") : "None"));
      r.AppendLine(string.Format(CultureInfo.InvariantCulture,
        "Estimated Time Stamp Counter Frequency: {0} MHz",
        Math.Round(estimatedTimeStampCounterFrequency * 100) * 0.01));
      r.AppendLine(string.Format(CultureInfo.InvariantCulture,
        "Estimated Time Stamp Counter Frequency Error: {0} Mhz",
        Math.Round(estimatedTimeStampCounterFrequency *
        estimatedTimeStampCounterFrequencyError * 1e5) * 1e-5));
      r.AppendLine(string.Format(CultureInfo.InvariantCulture,
        "Time Stamp Counter Frequency: {0} MHz",
        Math.Round(timeStampCounterFrequency * 100) * 0.01));   
      r.AppendLine();

      uint[] msrArray = GetMSRs();
      if (msrArray != null && msrArray.Length > 0) {
        for (int i = 0; i < cpuid.Length; i++) {
          r.AppendLine("MSR Core #" + (i + 1));
          r.AppendLine();
          r.AppendLine(" MSR       EDX       EAX");
          foreach (uint msr in msrArray)
            AppendMSRData(r, msr, cpuid[i][0].Thread);
          r.AppendLine();
        }
      }

      return r.ToString();
    }

    public override HardwareType HardwareType {
      get { return HardwareType.CPU; }
    }

    public bool HasModelSpecificRegisters {
      get { return hasModelSpecificRegisters; }
    }

    public bool HasTimeStampCounter {
      get { return hasTimeStampCounter; }
    }

    public double TimeStampCounterFrequency {
      get { return timeStampCounterFrequency; }
    }

    public override void Update() {
      if (hasTimeStampCounter && isInvariantTimeStampCounter) {

        // make sure always the same thread is used
        ulong mask = ThreadAffinity.Set(1UL << cpuid[0][0].Thread);

        // read time before and after getting the TSC to estimate the error
        long firstTime = Stopwatch.GetTimestamp();
        ulong timeStampCount = Opcode.Rdtsc();
        long time = Stopwatch.GetTimestamp();

        // restore the thread affinity mask
        ThreadAffinity.Set(mask);

        double delta = ((double)(time - lastTime)) / Stopwatch.Frequency;
        double error = ((double)(time - firstTime)) / Stopwatch.Frequency;

        // only use data if they are measured accuarte enough (max 0.1ms delay)
        if (error < 0.0001) {

          // ignore the first reading because there are no initial values 
          // ignore readings with too large or too small time window
          if (lastTime != 0 && delta > 0.5 && delta < 2) {

            // update the TSC frequency with the new value
            timeStampCounterFrequency =
              (timeStampCount - lastTimeStampCount) / (1e6 * delta);
          }

          lastTimeStampCount = timeStampCount;
          lastTime = time;
        }        
      }

      if (cpuLoad.IsAvailable) {
        cpuLoad.Update();
        for (int i = 0; i < coreLoads.Length; i++)
          coreLoads[i].Value = cpuLoad.GetCoreLoad(i);
        if (totalLoad != null)
          totalLoad.Value = cpuLoad.GetTotalLoad();
      }
    }
  }
}