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 #include "MemLibInternals.h"
  16
  17 /**
  18   Set Buffer to Value for Size bytes.
  19
  20   @param  Buffer   The memory to set.
  21   @param  Length   The number of bytes to set.
  22   @param  Value    The value of the set operation.
  23
  24   @return Buffer
  25
  26 **/
  27 VOID *
  28 EFIAPI
  29 InternalMemSetMem (
  30   OUT     VOID   *Buffer,
  31   IN      UINTN  Length,
  32   IN      UINT8  Value
  33   )
  34 {
  35   //
  36   // Declare the local variables that actually move the data elements as
  37   // volatile to prevent the optimizer from replacing this function with
  38   // the intrinsic memset()
  39   //
  40   volatile UINT8   *Pointer8;
  41   volatile UINT32  *Pointer32;
  42   volatile UINT64  *Pointer64;
  43   UINT32           Value32;
  44   UINT64           Value64;
  45
  46   if ((((UINTN)Buffer & 0x7) == 0) && (Length >= 8)) {
  47     // Generate the 64bit value
  48     Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
  49     Value64 = LShiftU64 (Value32, 32) | Value32;
  50
  51     Pointer64 = (UINT64 *)Buffer;
  52     while (Length >= 8) {
  53       *(Pointer64++) = Value64;
  54       Length        -= 8;
  55     }
  56
  57     // Finish with bytes if needed
  58     Pointer8 = (UINT8 *)Pointer64;
  59   } else if ((((UINTN)Buffer & 0x3) == 0) && (Length >= 4)) {
  60     // Generate the 32bit value
  61     Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
  62
  63     Pointer32 = (UINT32 *)Buffer;
  64     while (Length >= 4) {
  65       *(Pointer32++) = Value32;
  66       Length        -= 4;
  67     }
  68
  69     // Finish with bytes if needed
  70     Pointer8 = (UINT8 *)Pointer32;
  71   } else {
  72     Pointer8 = (UINT8 *)Buffer;
  73   }
  74
  75   while (Length-- > 0) {
  76     *(Pointer8++) = Value;
  77   }
  78
  79   return Buffer;
  80 }