MdePkg/Library/BaseMemoryLib/CompareMemWrapper.c

   1 /** @file
   2   CompareMem() implementation.
   3
   4   Copyright (c) 2006, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13   Module Name:  CompareMemWrapper.c
  14
  15   The following BaseMemoryLib instances share the same version of this file:
  16
  17     BaseMemoryLib
  18     BaseMemoryLibMmx
  19     BaseMemoryLibSse2
  20     BaseMemoryLibRepStr
  21     PeiMemoryLib
  22     DxeMemoryLib
  23
  24 **/
  25
  26 //
  27 // Include common header file for this module.
  28 //
  29 #include "CommonHeader.h"
  30
  31 #include "MemLibInternals.h"
  32
  33 /**
  34   Compares the contents of two buffers.
  35
  36   This function compares Length bytes of SourceBuffer to Length bytes of DestinationBuffer.
  37   If all Length bytes of the two buffers are identical, then 0 is returned.  Otherwise, the
  38   value returned is the first mismatched byte in SourceBuffer subtracted from the first
  39   mismatched byte in DestinationBuffer.
  40   If Length > 0 and DestinationBuffer is NULL and Length > 0, then ASSERT().
  41   If Length > 0 and SourceBuffer is NULL and Length > 0, then ASSERT().
  42   If Length is greater than (MAX_ADDRESS - DestinationBuffer + 1), then ASSERT().
  43   If Length is greater than (MAX_ADDRESS - SourceBuffer + 1), then ASSERT().
  44
  45
  46   @param  DestinationBuffer Pointer to the destination buffer to compare.
  47   @param  SourceBuffer      Pointer to the source buffer to compare.
  48   @param  Length            Number of bytes to compare.
  49
  50   @return 0                 All Length bytes of the two buffers are identical.
  51   @retval Non-zero          The first mismatched byte in SourceBuffer subtracted from the first
  52                             mismatched byte in DestinationBuffer.
  53
  54 **/
  55 INTN
  56 EFIAPI
  57 CompareMem (
  58   IN CONST VOID  *DestinationBuffer,
  59   IN CONST VOID  *SourceBuffer,
  60   IN UINTN       Length
  61   )
  62 {
  63   if (Length == 0) {
  64     return 0;
  65   }
  66   ASSERT (DestinationBuffer != NULL);
  67   ASSERT (SourceBuffer != NULL);
  68   ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)DestinationBuffer));
  69   ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)SourceBuffer));
  70
  71   return InternalMemCompareMem (DestinationBuffer, SourceBuffer, Length);
  72 }