MdePkg/Library/BaseMemoryLib/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 - 2018, Intel Corporation. All rights reserved.<BR>
  15 SPDX-License-Identifier: BSD-2-Clause-Patent
  16
  17 **/
  18
  19 #include "MemLibInternals.h"
  20
  21 /**
  22   Compares the contents of two buffers.
  23
  24   This function compares Length bytes of SourceBuffer to Length bytes of DestinationBuffer.
  25   If all Length bytes of the two buffers are identical, then 0 is returned.  Otherwise, the
  26   value returned is the first mismatched byte in SourceBuffer subtracted from the first
  27   mismatched byte in DestinationBuffer.
  28
  29   If Length > 0 and DestinationBuffer is NULL, then ASSERT().
  30   If Length > 0 and SourceBuffer is NULL, then ASSERT().
  31   If Length is greater than (MAX_ADDRESS - DestinationBuffer + 1), then ASSERT().
  32   If Length is greater than (MAX_ADDRESS - SourceBuffer + 1), then ASSERT().
  33
  34   @param  DestinationBuffer A pointer to the destination buffer to compare.
  35   @param  SourceBuffer      A pointer to the source buffer to compare.
  36   @param  Length            The number of bytes to compare.
  37
  38   @return 0                 All Length bytes of the two buffers are identical.
  39   @retval Non-zero          The first mismatched byte in SourceBuffer subtracted from the first
  40                             mismatched byte in DestinationBuffer.
  41
  42 **/
  43 INTN
  44 EFIAPI
  45 CompareMem (
  46   IN CONST VOID  *DestinationBuffer,
  47   IN CONST VOID  *SourceBuffer,
  48   IN UINTN       Length
  49   )
  50 {
  51   if (Length == 0 || DestinationBuffer == SourceBuffer) {
  52     return 0;
  53   }
  54   ASSERT (DestinationBuffer != NULL);
  55   ASSERT (SourceBuffer != NULL);
  56   ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)DestinationBuffer));
  57   ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)SourceBuffer));
  58
  59   return InternalMemCompareMem (DestinationBuffer, SourceBuffer, Length);
  60 }