ArmPkg/Library/CompilerIntrinsicsLib/Arm/memmove.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2011-2014, ARM Limited. All rights reserved.
   4 #
   5 # 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 <AsmMacroIoLib.h>
  16
  17 # VOID
  18 # EFIAPI
  19 # memmove (
  20 #  IN  VOID          *Destination,
  21 #  IN  CONST VOID    *Source,
  22 #  IN  UINT32        Size
  23 #  );
  24 ASM_FUNC(memmove)
  25   CMP     r2, #0
  26   BXEQ    lr
  27   CMP     r0, r1
  28   BXEQ    lr
  29   BHI     memmove_backward
  30
  31 memmove_forward:
  32   LDRB    r3, [r1], #1
  33   STRB    r3, [r0], #1
  34   SUBS    r2, r2, #1
  35   BXEQ    lr
  36   B       memmove_forward
  37
  38 memmove_backward:
  39   add     r0, r2
  40   add     r1, r2
  41 memmove_backward_loop:
  42   LDRB    r3, [r1, #-1]!
  43   STRB    r3, [r0, #-1]!
  44   SUBS    r2, r2, #1
  45   BXEQ    lr
  46   B       memmove_backward_loop