ArmPkg/Library/BaseMemoryLibVstm/Arm/CopyMem.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # CopyMem() worker for ARM
   4 #
   5 # This file started out as C code that did 64 bit moves if the buffer was
   6 # 32-bit aligned, else it does a byte copy. It also does a byte copy for
   7 # any trailing bytes. Update using VSTM/SLDM to do 128 byte copies.
   8 #
   9 # Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
  10 # This program and the accompanying materials
  11 # are licensed and made available under the terms and conditions of the BSD License
  12 # which accompanies this distribution.  The full text of the license may be found at
  13 # http://opensource.org/licenses/bsd-license.php
  14 #
  15 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  16 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  17 #
  18 #------------------------------------------------------------------------------
  19
  20 #include <AsmMacroIoLib.h>
  21
  22 /**
  23   Copy Length bytes from Source to Destination. Overlap is OK.
  24
  25   This implementation
  26
  27   @param  Destination Target of copy
  28   @param  Source      Place to copy from
  29   @param  Length      Number of bytes to copy
  30
  31   @return Destination
  32
  33
  34 VOID *
  35 EFIAPI
  36 InternalMemCopyMem (
  37   OUT     VOID                      *DestinationBuffer,
  38   IN      CONST VOID                *SourceBuffer,
  39   IN      UINTN                     Length
  40   )
  41 **/
  42 ASM_FUNC(InternalMemCopyMem)
  43   stmfd  sp!, {r4, r9, lr}
  44   tst  r0, #3
  45   mov  r4, r0
  46   mov  r9, r0
  47   mov  ip, r2
  48   mov  lr, r1
  49   movne  r0, #0
  50   bne  L4
  51   tst  r1, #3
  52   movne  r3, #0
  53   moveq  r3, #1
  54   cmp  r2, #127
  55   movls  r0, #0
  56   andhi  r0, r3, #1
  57 L4:
  58   cmp  r4, r1
  59   bcc  L26
  60   bls  L7
  61   rsb  r3, r1, r4
  62   cmp  ip, r3
  63   bcc  L26
  64   cmp  ip, #0
  65   beq  L7
  66   add  r9, r4, ip
  67   add  lr, ip, r1
  68   b  L16
  69 L29:
  70   sub  ip, ip, #8
  71   cmp  ip, #7
  72   ldrd  r2, [lr, #-8]!
  73   movls  r0, #0
  74   cmp  ip, #0
  75   strd  r2, [r9, #-8]!
  76   beq  L7
  77 L16:
  78   cmp  r0, #0
  79   bne  L29
  80   sub  r3, lr, #1
  81   sub  ip, ip, #1
  82   ldrb  r3, [r3, #0]
  83   sub  r2, r9, #1
  84   cmp  ip, #0
  85   sub  r9, r9, #1
  86   sub  lr, lr, #1
  87   strb  r3, [r2, #0]
  88   bne  L16
  89   b   L7
  90 L11:
  91   ldrb  r3, [lr], #1
  92   sub  ip, ip, #1
  93   strb  r3, [r9], #1
  94 L26:
  95   cmp  ip, #0
  96   beq  L7
  97 L30:
  98   cmp  r0, #0
  99   beq  L11
 100   sub  ip, ip, #128          // 32
 101   cmp  ip, #127              // 31
 102   vldm     lr!, {d0-d15}
 103   movls  r0, #0
 104   cmp  ip, #0
 105   vstm  r9!, {d0-d15}
 106   bne  L30
 107 L7:
 108   dsb
 109   mov  r0, r4
 110   ldmfd  sp!, {r4, r9, pc}
 111
 112