/** @file

  DXE Core library services.

Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>

SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "DxeMain.h"

//

// Lock Stuff

//

/**

  Initialize a basic mutual exclusion lock.   Each lock

  provides mutual exclusion access at it's task priority

  level.  Since there is no-premption (at any TPL) or

  multiprocessor support, acquiring the lock only consists

  of raising to the locks TPL.

  @param  Lock               The EFI_LOCK structure to initialize

  @retval EFI_SUCCESS        Lock Owned.

  @retval EFI_ACCESS_DENIED  Reentrant Lock Acquisition, Lock not Owned.

**/

EFI_STATUS

CoreAcquireLockOrFail (

  IN EFI_LOCK  *Lock

  )

{

  ASSERT (Lock != NULL);

  ASSERT (Lock->Lock != EfiLockUninitialized);

  if (Lock->Lock == EfiLockAcquired) {

    //

    // Lock is already owned, so bail out

    //

    return EFI_ACCESS_DENIED;

  }

  Lock->OwnerTpl = CoreRaiseTpl (Lock->Tpl);

  Lock->Lock = EfiLockAcquired;

  return EFI_SUCCESS;

}

/**

  Raising to the task priority level of the mutual exclusion

  lock, and then acquires ownership of the lock.

  @param  Lock               The lock to acquire

  @return Lock owned

**/

VOID

CoreAcquireLock (

  IN EFI_LOCK  *Lock

  )

{

  ASSERT (Lock != NULL);

  ASSERT (Lock->Lock == EfiLockReleased);

  Lock->OwnerTpl = CoreRaiseTpl (Lock->Tpl);

  Lock->Lock     = EfiLockAcquired;

}

/**

  Releases ownership of the mutual exclusion lock, and

  restores the previous task priority level.

  @param  Lock               The lock to release

  @return Lock unowned

**/

VOID

CoreReleaseLock (

  IN EFI_LOCK  *Lock

  )

{

  EFI_TPL Tpl;

  ASSERT (Lock != NULL);

  ASSERT (Lock->Lock == EfiLockAcquired);

  Tpl = Lock->OwnerTpl;

  Lock->Lock = EfiLockReleased;

  CoreRestoreTpl (Tpl);

}