MdePkg/Library/PeiServicesTablePointerLibIdt/PeiServicesTablePointer.c

   1 /** @file
   2   PEI Services Table Pointer Library for IA-32 and X64.
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation.<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include <PiPei.h>
  16
  17 #include <Library/BaseLib.h>
  18 #include <Library/PeiServicesTablePointerLib.h>
  19 #include <Library/DebugLib.h>
  20
  21 /**
  22
  23   The function returns the pointer to PeiServicee following
  24   PI1.0.
  25
  26   For IA32, the four-bytes field immediately prior to new IDT
  27   base addres is used to save the EFI_PEI_SERVICES**.
  28   For x64, the eight-bytes field immediately prior to new IDT
  29   base addres is used to save the EFI_PEI_SERVICES**
  30
  31   @return  The pointer to PeiServices.
  32
  33 **/
  34 EFI_PEI_SERVICES **
  35 EFIAPI
  36 GetPeiServicesTablePointer (
  37   VOID
  38   )
  39 {
  40   EFI_PEI_SERVICES  **PeiServices;
  41   IA32_DESCRIPTOR   Idtr;
  42
  43   AsmReadIdtr (&Idtr);
  44   PeiServices = (EFI_PEI_SERVICES **) (*(UINTN*)(Idtr.Base - sizeof (UINTN)));
  45   ASSERT (PeiServices != NULL);
  46   return PeiServices;
  47 }
  48
  49 /**
  50
  51   The function sets the pointer to PeiServicee following
  52   PI1.0.
  53
  54   For IA32, the four-bytes field immediately prior to new IDT
  55   base addres is used to save the EFI_PEI_SERVICES**.
  56   For x64, the eight-bytes field immediately prior to new IDT
  57   base addres is used to save the EFI_PEI_SERVICES**
  58
  59   @param PeiServicesTablePointer  The pointer to PeiServices.
  60
  61 **/
  62 VOID
  63 EFIAPI
  64 SetPeiServicesTablePointer (
  65   EFI_PEI_SERVICES ** PeiServicesTablePointer
  66   )
  67 {
  68   IA32_DESCRIPTOR   Idtr;
  69
  70   AsmReadIdtr (&Idtr);
  71   (*(UINTN*)(Idtr.Base - sizeof (UINTN))) = (UINTN)PeiServicesTablePointer;
  72 }
  73
  74