ArmPkg/Library/BaseMemoryLibVstm/Arm/CopyMem.asm

;------------------------------------------------------------------------------ 
;
; CopyMem() worker for ARM
;
; This file started out as C code that did 64 bit moves if the buffer was
; 32-bit aligned, else it does a byte copy. It also does a byte copy for
; any trailing bytes. Update using VSTM/SLDM to do 128 byte copies.
;
; Copyright (c) 2008 - 2010, Apple Inc. 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.
;
;------------------------------------------------------------------------------

/**
  Copy Length bytes from Source to Destination. Overlap is OK.

  This implementation 

  @param  Destination Target of copy
  @param  Source      Place to copy from
  @param  Length      Number of bytes to copy

  @return Destination


VOID *
EFIAPI
InternalMemCopyMem (
  OUT     VOID                      *DestinationBuffer,
  IN      CONST VOID                *SourceBuffer,
  IN      UINTN                     Length
  )
**/
  EXPORT InternalMemCopyMem

  AREA AsmMemStuff, CODE, READONLY

InternalMemCopyMem
  stmfd  sp!, {r4, r9, lr}
  tst  r0, #3
  mov  r4, r0
  mov  r9, r0
  mov  ip, r2
  mov  lr, r1
  movne  r0, #0
  bne  L4
  tst  r1, #3
  movne  r3, #0
  moveq  r3, #1
  cmp  r2, #127
  movls  r0, #0
  andhi  r0, r3, #1
L4
  cmp  r4, r1
  bcc  L26
  bls  L7
  rsb  r3, r1, r4
  cmp  ip, r3
  bcc  L26
  cmp  ip, #0
  beq  L7
  add  r9, r4, ip
  add  lr, ip, r1
  b  L16
L29
  sub  ip, ip, #8
  cmp  ip, #7
  ldrd  r2, [lr, #-8]!
  movls  r0, #0
  cmp  ip, #0
  strd  r2, [r9, #-8]!
  beq  L7
L16
  cmp  r0, #0
  bne  L29
  sub  r3, lr, #1
  sub  ip, ip, #1
  ldrb  r3, [r3, #0]  
  sub  r2, r9, #1
  cmp  ip, #0
  sub  r9, r9, #1
  sub  lr, lr, #1
  strb  r3, [r2, #0]
  bne  L16
  b   L7
L11
  ldrb  r3, [lr], #1  
  sub  ip, ip, #1
  strb  r3, [r9], #1
L26
  cmp  ip, #0
  beq  L7
L30
  cmp  r0, #0
  beq  L11
  sub  ip, ip, #128          // 32
  cmp  ip, #127              // 31
  vldm     lr!, {d0-d15}
  movls  r0, #0
  cmp  ip, #0
  vstm  r9!, {d0-d15}
  bne  L30
L7
  dsb
  mov  r0, r4
  ldmfd  sp!, {r4, r9, pc}

  END