MdePkg/BaseMemoryLibOptDxe: add accelerated ARM routines

[mirror_edk2.git] / MdePkg / Library / BaseMemoryLibOptDxe / Arm / CopyMem.asm

;------------------------------------------------------------------------------\r
;\r
; CopyMem() worker for ARM\r
;\r
; This file started out as C code that did 64 bit moves if the buffer was\r
; 32-bit aligned, else it does a byte copy. It also does a byte copy for\r
; any trailing bytes. It was updated to do 32-byte copies using stm/ldm.\r
;\r
; Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>\r
; Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>\r
; This program and the accompanying materials\r
; are licensed and made available under the terms and conditions of the BSD License\r
; which accompanies this distribution.  The full text of the license may be found at\r
; http://opensource.org/licenses/bsd-license.php\r
;\r
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
;\r
;------------------------------------------------------------------------------\r
\r
    EXPORT  InternalMemCopyMem\r
    AREA    SetMem, CODE, READONLY\r
    THUMB\r
\r
InternalMemCopyMem\r
  stmfd  sp!, {r4-r11, lr}\r
  // Save the input parameters in extra registers (r11 = destination, r14 = source, r12 = length)\r
  mov  r11, r0\r
  mov  r10, r0\r
  mov  r12, r2\r
  mov  r14, r1\r
\r
memcopy_check_overlapped\r
  cmp  r11, r1\r
  // If (dest < source)\r
  bcc  memcopy_check_optim_default\r
\r
  // If (source + length < dest)\r
  rsb  r3, r1, r11\r
  cmp  r12, r3\r
  bcc  memcopy_check_optim_default\r
  b     memcopy_check_optim_overlap\r
\r
memcopy_check_optim_default\r
  // Check if we can use an optimized path ((length >= 32) && destination word-aligned && source word-aligned) for the memcopy (optimized path if r0 == 1)\r
  tst  r0, #0xF\r
  movne  r0, #0\r
  bne   memcopy_default\r
  tst  r1, #0xF\r
  movne  r3, #0\r
  moveq  r3, #1\r
  cmp  r2, #31\r
  movls  r0, #0\r
  andhi  r0, r3, #1\r
  b     memcopy_default\r
\r
memcopy_check_optim_overlap\r
  // r10 = dest_end, r14 = source_end\r
  add  r10, r11, r12\r
  add  r14, r12, r1\r
\r
  // Are we in the optimized case ((length >= 32) && dest_end word-aligned && source_end word-aligned)\r
  cmp  r2, #31\r
  movls  r0, #0\r
  movhi  r0, #1\r
  tst  r10, #0xF\r
  movne  r0, #0\r
  tst  r14, #0xF\r
  movne  r0, #0\r
  b  memcopy_overlapped\r
\r
memcopy_overlapped_non_optim\r
  // We read 1 byte from the end of the source buffer\r
  sub  r3, r14, #1\r
  sub  r12, r12, #1\r
  ldrb  r3, [r3, #0]\r
  sub  r2, r10, #1\r
  cmp  r12, #0\r
  // We write 1 byte at the end of the dest buffer\r
  sub  r10, r10, #1\r
  sub  r14, r14, #1\r
  strb  r3, [r2, #0]\r
  bne  memcopy_overlapped_non_optim\r
  b   memcopy_end\r
\r
// r10 = dest_end, r14 = source_end\r
memcopy_overlapped\r
  // Are we in the optimized case ?\r
  cmp  r0, #0\r
  beq  memcopy_overlapped_non_optim\r
\r
  // Optimized Overlapped - Read 32 bytes\r
  sub  r14, r14, #32\r
  sub  r12, r12, #32\r
  cmp  r12, #31\r
  ldmia  r14, {r2-r9}\r
\r
  // If length is less than 32 then disable optim\r
  movls  r0, #0\r
\r
  cmp  r12, #0\r
\r
  // Optimized Overlapped - Write 32 bytes\r
  sub  r10, r10, #32\r
  stmia  r10, {r2-r9}\r
\r
  // while (length != 0)\r
  bne  memcopy_overlapped\r
  b   memcopy_end\r
\r
memcopy_default_non_optim\r
  // Byte copy\r
  ldrb  r3, [r14], #1\r
  sub  r12, r12, #1\r
  strb  r3, [r10], #1\r
\r
memcopy_default\r
  cmp  r12, #0\r
  beq  memcopy_end\r
\r
// r10 = dest, r14 = source\r
memcopy_default_loop\r
  cmp  r0, #0\r
  beq  memcopy_default_non_optim\r
\r
  // Optimized memcopy - Read 32 Bytes\r
  sub  r12, r12, #32\r
  cmp  r12, #31\r
  ldmia  r14!, {r2-r9}\r
\r
  // If length is less than 32 then disable optim\r
  movls  r0, #0\r
\r
  cmp  r12, #0\r
\r
  // Optimized memcopy - Write 32 Bytes\r
  stmia  r10!, {r2-r9}\r
\r
  // while (length != 0)\r
  bne  memcopy_default_loop\r
\r
memcopy_end\r
  mov  r0, r11\r
  ldmfd  sp!, {r4-r11, pc}\r
\r
  END\r
\r