uefi/linaro-edk2/MdePkg/Library/BaseLib/SwitchStack.c

/** @file
  Switch Stack functions.

  Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
  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.  This function
  supports a variable number of arguments following the NewStack parameter.
  These additional arguments are 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  ...         This variable argument list is ignored for IA32, x64, and EBC.  
                      For IPF, this variable argument list is expected to contain 
                      a single parameter of type VOID * that specifies the new backing 
                      store pointer.


**/
VOID
EFIAPI
SwitchStack (
  IN      SWITCH_STACK_ENTRY_POINT  EntryPoint,
  IN      VOID                      *Context1,  OPTIONAL
  IN      VOID                      *Context2,  OPTIONAL
  IN      VOID                      *NewStack,
  ...
  )
{
  VA_LIST    Marker;

  ASSERT (EntryPoint != NULL);
  ASSERT (NewStack != NULL);

  //
  // New stack must be aligned with CPU_STACK_ALIGNMENT
  //
  ASSERT (((UINTN)NewStack & (CPU_STACK_ALIGNMENT - 1)) == 0);

  VA_START (Marker, NewStack);

  InternalSwitchStack (EntryPoint, Context1, Context2, NewStack, Marker);

  VA_END (Marker);

  //
  // InternalSwitchStack () will never return
  //
  ASSERT (FALSE);
}