/*

  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);

    }

  }

}