MdePkg/Library/BaseLib/Arm/GccInline.c

   1 /** @file
   2   GCC inline implementation of BaseLib processor specific functions.
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation<BR>
   5   Portions copyright (c) 2008-2009 Apple Inc.<BR>
   6   All rights reserved. This program and the accompanying materials
   7   are licensed and made available under the terms and conditions of the BSD License
   8   which accompanies this distribution.  The full text of the license may be found at
   9   http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13
  14 **/
  15
  16 #include "BaseLibInternals.h"
  17
  18 /**
  19   Requests CPU to pause for a short period of time.
  20
  21   Requests CPU to pause for a short period of time. Typically used in MP
  22   systems to prevent memory starvation while waiting for a spin lock.
  23
  24 **/
  25 VOID
  26 EFIAPI
  27 CpuPause (
  28   VOID
  29   )
  30 {
  31   __asm__ __volatile__ (
  32     "nop\n\t"
  33     "nop\n\t"
  34     "nop\n\t"
  35     "nop\n\t"
  36     "nop\n\t"
  37     );
  38 }
  39
  40 VOID
  41 EFIAPI
  42 InternalSwitchStackAsm (
  43   SWITCH_STACK_ENTRY_POINT EntryPoint,
  44   VOID  *Context,
  45   VOID  *Context2,
  46   VOID  *NewStack
  47   )
  48 {
  49   __asm__ __volatile__ (
  50     "mov  lr, %0\n\t"
  51     "mov  sp, %3\n\t"
  52     "mov  %r0, %1\n\t"
  53     "mov  %r1, %2\n\t"
  54     "bx   lr\n\t"
  55     : /* no output operand */
  56     : "r" (EntryPoint),
  57       "r" (Context),
  58       "r" (Context2),
  59       "r" (NewStack)
  60     );
  61 }