MdePkg/Library/BaseMemoryLib/CopyMem.c

   1 /** @file
   2   Implementation of the InternalMemCopyMem routine. This function is broken
   3   out into its own source file so that it can be excluded from a build for a
   4   particular platform easily if an optimized version is desired.
   5
   6   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
   7   Copyright (c) 2012 - 2013, ARM Ltd. All rights reserved.<BR>
   8   Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
   9
  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
  21
  22
  23 #include "MemLibInternals.h"
  24
  25 /**
  26   Copy Length bytes from Source to Destination.
  27
  28   @param  DestinationBuffer The target of the copy request.
  29   @param  SourceBuffer      The place to copy from.
  30   @param  Length            The number of bytes to copy.
  31
  32   @return Destination
  33
  34 **/
  35 VOID *
  36 EFIAPI
  37 InternalMemCopyMem (
  38   OUT     VOID                      *DestinationBuffer,
  39   IN      CONST VOID                *SourceBuffer,
  40   IN      UINTN                     Length
  41   )
  42 {
  43   //
  44   // Declare the local variables that actually move the data elements as
  45   // volatile to prevent the optimizer from replacing this function with
  46   // the intrinsic memcpy()
  47   //
  48   volatile UINT8                    *Destination8;
  49   CONST UINT8                       *Source8;
  50   volatile UINT32                   *Destination32;
  51   CONST UINT32                      *Source32;
  52   volatile UINT64                   *Destination64;
  53   CONST UINT64                      *Source64;
  54   UINTN                             Alignment;
  55
  56   if ((((UINTN)DestinationBuffer & 0x7) == 0) && (((UINTN)SourceBuffer & 0x7) == 0) && (Length >= 8)) {
  57     if (SourceBuffer > DestinationBuffer) {
  58       Destination64 = (UINT64*)DestinationBuffer;
  59       Source64 = (CONST UINT64*)SourceBuffer;
  60       while (Length >= 8) {
  61         *(Destination64++) = *(Source64++);
  62         Length -= 8;
  63       }
  64
  65       // Finish if there are still some bytes to copy
  66       Destination8 = (UINT8*)Destination64;
  67       Source8 = (CONST UINT8*)Source64;
  68       while (Length-- != 0) {
  69         *(Destination8++) = *(Source8++);
  70       }
  71     } else if (SourceBuffer < DestinationBuffer) {
  72       Destination64 = (UINT64*)((UINTN)DestinationBuffer + Length);
  73       Source64 = (CONST UINT64*)((UINTN)SourceBuffer + Length);
  74
  75       // Destination64 and Source64 were aligned on a 64-bit boundary
  76       // but if length is not a multiple of 8 bytes then they won't be
  77       // anymore.
  78
  79       Alignment = Length & 0x7;
  80       if (Alignment != 0) {
  81         Destination8 = (UINT8*)Destination64;
  82         Source8 = (CONST UINT8*)Source64;
  83
  84         while (Alignment-- != 0) {
  85           *(--Destination8) = *(--Source8);
  86           --Length;
  87         }
  88         Destination64 = (UINT64*)Destination8;
  89         Source64 = (CONST UINT64*)Source8;
  90       }
  91
  92       while (Length > 0) {
  93         *(--Destination64) = *(--Source64);
  94         Length -= 8;
  95       }
  96     }
  97   } else if ((((UINTN)DestinationBuffer & 0x3) == 0) && (((UINTN)SourceBuffer & 0x3) == 0) && (Length >= 4)) {
  98     if (SourceBuffer > DestinationBuffer) {
  99       Destination32 = (UINT32*)DestinationBuffer;
 100       Source32 = (CONST UINT32*)SourceBuffer;
 101       while (Length >= 4) {
 102         *(Destination32++) = *(Source32++);
 103         Length -= 4;
 104       }
 105
 106       // Finish if there are still some bytes to copy
 107       Destination8 = (UINT8*)Destination32;
 108       Source8 = (CONST UINT8*)Source32;
 109       while (Length-- != 0) {
 110         *(Destination8++) = *(Source8++);
 111       }
 112     } else if (SourceBuffer < DestinationBuffer) {
 113       Destination32 = (UINT32*)((UINTN)DestinationBuffer + Length);
 114       Source32 = (CONST UINT32*)((UINTN)SourceBuffer + Length);
 115
 116       // Destination32 and Source32 were aligned on a 32-bit boundary
 117       // but if length is not a multiple of 4 bytes then they won't be
 118       // anymore.
 119
 120       Alignment = Length & 0x3;
 121       if (Alignment != 0) {
 122         Destination8 = (UINT8*)Destination32;
 123         Source8 = (CONST UINT8*)Source32;
 124
 125         while (Alignment-- != 0) {
 126           *(--Destination8) = *(--Source8);
 127           --Length;
 128         }
 129         Destination32 = (UINT32*)Destination8;
 130         Source32 = (CONST UINT32*)Source8;
 131       }
 132
 133       while (Length > 0) {
 134         *(--Destination32) = *(--Source32);
 135         Length -= 4;
 136       }
 137     }
 138   } else {
 139     if (SourceBuffer > DestinationBuffer) {
 140       Destination8 = (UINT8*)DestinationBuffer;
 141       Source8 = (CONST UINT8*)SourceBuffer;
 142       while (Length-- != 0) {
 143         *(Destination8++) = *(Source8++);
 144       }
 145     } else if (SourceBuffer < DestinationBuffer) {
 146       Destination8 = (UINT8*)DestinationBuffer + Length;
 147       Source8 = (CONST UINT8*)SourceBuffer + Length;
 148       while (Length-- != 0) {
 149         *(--Destination8) = *(--Source8);
 150       }
 151     }
 152   }
 153   return DestinationBuffer;
 154 }