audk/MdePkg/Library/BaseLib/Ia32/InternalSwitchStack.c

/** @file
  SwitchStack() function for IA-32.

  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.

**/

#include "BaseLibInternals.h"

/**
  Transfers control to a function starting with a new stack.

  Transfers control to the function specified by EntryPoint using the
  new stack specified by NewStack and passing in the parameters specified
  by Context1 and Context2.  Context1 and Context2 are optional and may
  be NULL.  The function EntryPoint must never return.
  Marker will be ignored on IA-32, x64, and EBC.
  IPF CPUs expect one additional parameter of type VOID * that specifies
  the new backing store pointer.

  If EntryPoint is NULL, then ASSERT().
  If NewStack is NULL, then ASSERT().

  @param  EntryPoint  A pointer to function to call with the new stack.
  @param  Context1    A pointer to the context to pass into the EntryPoint
                      function.
  @param  Context2    A pointer to the context to pass into the EntryPoint
                      function.
  @param  NewStack    A pointer to the new stack to use for the EntryPoint
                      function.
  @param  Marker      VA_LIST marker for the variable argument list.

**/
VOID
EFIAPI
InternalSwitchStack (
  IN      SWITCH_STACK_ENTRY_POINT  EntryPoint,
  IN      VOID                      *Context1,   OPTIONAL
  IN      VOID                      *Context2,   OPTIONAL
  IN      VOID                      *NewStack,
  IN      VA_LIST                   Marker
  )
{
  BASE_LIBRARY_JUMP_BUFFER  JumpBuffer;

  //
  // Stack should be aligned with CPU_STACK_ALIGNMENT
  //
  ASSERT (((UINTN)NewStack & (CPU_STACK_ALIGNMENT - 1)) == 0);

  JumpBuffer.Eip = (UINTN)EntryPoint;
  JumpBuffer.Esp = (UINTN)NewStack - sizeof (VOID*);
  JumpBuffer.Esp -= sizeof (Context1) + sizeof (Context2);
  ((VOID**)JumpBuffer.Esp)[1] = Context1;
  ((VOID**)JumpBuffer.Esp)[2] = Context2;

  LongJump (&JumpBuffer, (UINTN)-1);
}