Import some Pei and Dxe related instances for MdePkg.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@2712 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/UefiBootServicesTableLib/UefiBootServicesTableLib.c

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+/** @file
+  UEFI Boot Services Table Library.
+
+  Copyright (c) 2006 - 2007, Intel Corporation<BR>
+  All rights reserved. This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+  Module Name:  UefiBootServicesTableLib.c
+
+**/
+
+//
+// Include common header file for this module.
+//
+#include "CommonHeader.h"
+
+EFI_HANDLE         gImageHandle = NULL;
+EFI_SYSTEM_TABLE   *gST         = NULL;
+EFI_BOOT_SERVICES  *gBS         = NULL;
+
+/**
+  The constructor function caches the pointer of Boot Services Table.
+  
+  The constructor function caches the pointer of Boot Services Table through System Table.
+  It will ASSERT() if the pointer of System Table is NULL.
+  It will ASSERT() if the pointer of Boot Services Table is NULL.
+  It will always return EFI_SUCCESS.
+
+  @param  ImageHandle   The firmware allocated handle for the EFI image.
+  @param  SystemTable   A pointer to the EFI System Table.
+
+  @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.
+
+**/
+EFI_STATUS
+EFIAPI
+UefiBootServicesTableLibConstructor (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  //
+  // Cache the Image Handle
+  //
+  gImageHandle = ImageHandle;
+  ASSERT (gImageHandle != NULL);
+
+  //
+  // Cache pointer to the EFI System Table
+  //
+  gST = SystemTable;
+  ASSERT (gST != NULL);
+
+  //
+  // Cache pointer to the EFI Boot Services Table
+  //
+  gBS = SystemTable->BootServices;
+  ASSERT (gBS != NULL);
+
+  return EFI_SUCCESS;
+}