MdePkg/Library/UefiMemoryLib/CompareMemWrapper.c

   1 /** @file
   2   CompareMem() implementation.
   3
   4   The following BaseMemoryLib instances contain the same copy of this file:
   5     BaseMemoryLib
   6     BaseMemoryLibMmx
   7     BaseMemoryLibSse2
   8     BaseMemoryLibRepStr
   9     BaseMemoryLibOptDxe
  10     BaseMemoryLibOptPei
  11     PeiMemoryLib
  12     UefiMemoryLib
  13
  14 Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
  15 This program and the accompanying materials
  16 are licensed and made available under the terms and conditions of the BSD License
  17 which accompanies this distribution.  The full text of the license may be found at
  18 http://opensource.org/licenses/bsd-license.php
  19
  20 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  21 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  22
  23 **/
  24
  25 #include "MemLibInternals.h"
  26
  27 /**
  28   Compares the contents of two buffers.
  29
  30   This function compares Length bytes of SourceBuffer to Length bytes of DestinationBuffer.
  31   If all Length bytes of the two buffers are identical, then 0 is returned.  Otherwise, the
  32   value returned is the first mismatched byte in SourceBuffer subtracted from the first
  33   mismatched byte in DestinationBuffer.
  34
  35   If Length > 0 and DestinationBuffer is NULL, then ASSERT().
  36   If Length > 0 and SourceBuffer is NULL, then ASSERT().
  37   If Length is greater than (MAX_ADDRESS - DestinationBuffer + 1), then ASSERT().
  38   If Length is greater than (MAX_ADDRESS - SourceBuffer + 1), then ASSERT().
  39
  40   @param  DestinationBuffer The pointer to the destination buffer to compare.
  41   @param  SourceBuffer      The pointer to the source buffer to compare.
  42   @param  Length            The number of bytes to compare.
  43
  44   @return 0                 All Length bytes of the two buffers are identical.
  45   @retval Non-zero          The first mismatched byte in SourceBuffer subtracted from the first
  46                             mismatched byte in DestinationBuffer.
  47
  48 **/
  49 INTN
  50 EFIAPI
  51 CompareMem (
  52   IN CONST VOID  *DestinationBuffer,
  53   IN CONST VOID  *SourceBuffer,
  54   IN UINTN       Length
  55   )
  56 {
  57   if (Length == 0 || DestinationBuffer == SourceBuffer) {
  58     return 0;
  59   }
  60   ASSERT (DestinationBuffer != NULL);
  61   ASSERT (SourceBuffer != NULL);
  62   ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)DestinationBuffer));
  63   ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)SourceBuffer));
  64
  65   return InternalMemCompareMem (DestinationBuffer, SourceBuffer, Length);
  66 }