/*
 
  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) 2011 Michael Möller <mmoeller@openhardwaremonitor.org>
	
*/

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Text;

namespace OpenHardwareMonitor.Hardware {

  internal static class FirmwareTable {

    public static byte[] GetTable(Provider provider, string table) {
      int id = table[3] << 24 | table[2] << 16 | table[1] << 8 | table[0];
      return GetTable(provider, id);
    }

    public static byte[] GetTable(Provider provider, int table) {
      
      int size;
      try {
        size = NativeMethods.GetSystemFirmwareTable(provider, table, 
          IntPtr.Zero, 0);
      } catch (DllNotFoundException) { return null; } 
        catch (EntryPointNotFoundException) { return null; }

      if (size <= 0)
        return null;

      IntPtr nativeBuffer = Marshal.AllocHGlobal(size);
      NativeMethods.GetSystemFirmwareTable(provider, table, nativeBuffer, size);

      if (Marshal.GetLastWin32Error() != 0)
        return null;

      byte[] buffer = new byte[size];
      Marshal.Copy(nativeBuffer, buffer, 0, size);
      Marshal.FreeHGlobal(nativeBuffer);

      return buffer;
    }

    public static string[] EnumerateTables(Provider provider) {
      int size;
      try {
        size = NativeMethods.EnumSystemFirmwareTables(
          provider, IntPtr.Zero, 0);
      } catch (DllNotFoundException) { return null; } 
        catch (EntryPointNotFoundException) { return null; }

      IntPtr nativeBuffer = Marshal.AllocHGlobal(size);
      NativeMethods.EnumSystemFirmwareTables(
        provider, nativeBuffer, size);
      byte[] buffer = new byte[size];
      Marshal.Copy(nativeBuffer, buffer, 0, size);
      Marshal.FreeHGlobal(nativeBuffer);

      string[] result = new string[size / 4];
      for (int i = 0; i < result.Length; i++) 
        result[i] = Encoding.ASCII.GetString(buffer, 4 * i, 4);

      return result;
    }

    public enum Provider : int {
      ACPI = (byte)'A' << 24 | (byte)'C' << 16 | (byte)'P' << 8 | (byte)'I',
      FIRM = (byte)'F' << 24 | (byte)'I' << 16 | (byte)'R' << 8 | (byte)'M',
      RSMB = (byte)'R' << 24 | (byte)'S' << 16 | (byte)'M' << 8 | (byte)'B'
    }

    private static class NativeMethods {
      private const string KERNEL = "kernel32.dll";

      [DllImport(KERNEL, CallingConvention = CallingConvention.Winapi,
        SetLastError = true)]
      public static extern int EnumSystemFirmwareTables(
        Provider firmwareTableProviderSignature,
        IntPtr firmwareTableBuffer, int bufferSize);

      [DllImport(KERNEL, CallingConvention = CallingConvention.Winapi,
        SetLastError = true)]
      public static extern int GetSystemFirmwareTable(
        Provider firmwareTableProviderSignature,
        int firmwareTableID, IntPtr firmwareTableBuffer, int bufferSize);
    }
  }
}