MdePkg/Library/BaseMemoryLib/SetMem.c

   1 /** @file
   2   Implementation of the EfiSetMem routine. This function is broken
   3   out into its own source file so that it can be excluded from a
   4   build for a particular platform easily if an optimized version
   5   is desired.
   6
   7   Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
   8   Copyright (c) 2012 - 2013, ARM Ltd. All rights reserved.<BR>
   9   Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
  10
  11   SPDX-License-Identifier: BSD-2-Clause-Patent
  12
  13 **/
  14
  15
  16
  17
  18 #include "MemLibInternals.h"
  19
  20 /**
  21   Set Buffer to Value for Size bytes.
  22
  23   @param  Buffer   The memory to set.
  24   @param  Length   The number of bytes to set.
  25   @param  Value    The value of the set operation.
  26
  27   @return Buffer
  28
  29 **/
  30 VOID *
  31 EFIAPI
  32 InternalMemSetMem (
  33   OUT     VOID                      *Buffer,
  34   IN      UINTN                     Length,
  35   IN      UINT8                     Value
  36   )
  37 {
  38   //
  39   // Declare the local variables that actually move the data elements as
  40   // volatile to prevent the optimizer from replacing this function with
  41   // the intrinsic memset()
  42   //
  43   volatile UINT8                    *Pointer8;
  44   volatile UINT32                   *Pointer32;
  45   volatile UINT64                   *Pointer64;
  46   UINT32                            Value32;
  47   UINT64                            Value64;
  48
  49   if ((((UINTN)Buffer & 0x7) == 0) && (Length >= 8)) {
  50     // Generate the 64bit value
  51     Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
  52     Value64 = LShiftU64 (Value32, 32) | Value32;
  53
  54     Pointer64 = (UINT64*)Buffer;
  55     while (Length >= 8) {
  56       *(Pointer64++) = Value64;
  57       Length -= 8;
  58     }
  59
  60     // Finish with bytes if needed
  61     Pointer8 = (UINT8*)Pointer64;
  62   } else if ((((UINTN)Buffer & 0x3) == 0) && (Length >= 4)) {
  63     // Generate the 32bit value
  64     Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
  65
  66     Pointer32 = (UINT32*)Buffer;
  67     while (Length >= 4) {
  68       *(Pointer32++) = Value32;
  69       Length -= 4;
  70     }
  71
  72     // Finish with bytes if needed
  73     Pointer8 = (UINT8*)Pointer32;
  74   } else {
  75     Pointer8 = (UINT8*)Buffer;
  76   }
  77   while (Length-- > 0) {
  78     *(Pointer8++) = Value;
  79   }
  80   return Buffer;
  81 }