EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/EfiSetMem.c

   1 /*++
   2
   3 Copyright (c) 2006, Intel Corporation
   4 All rights reserved. This program and the accompanying materials
   5 are licensed and made available under the terms and conditions of the BSD License
   6 which accompanies this distribution.  The full text of the license may be found at
   7 http://opensource.org/licenses/bsd-license.php
   8
   9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11
  12 Module Name:
  13
  14   EfiSetMem.c
  15
  16 Abstract:
  17
  18   This is the code that supports IA32-optimized SetMem service
  19
  20 --*/
  21
  22 #include "Tiano.h"
  23
  24 VOID
  25 EfiCommonLibSetMem (
  26   IN VOID   *Buffer,
  27   IN UINTN  Count,
  28   IN UINT8  Value
  29   )
  30 /*++
  31
  32 Input:  VOID   *Buffer - Pointer to buffer to write
  33         UINTN  Count   - Number of bytes to write
  34         UINT8  Value   - Value to write
  35
  36 Output: None.
  37
  38 Saves:
  39
  40 Modifies:
  41
  42 Description:  This function is an optimized set-memory function.
  43
  44 Notes:  This function tries to set memory 8 bytes at a time. As a result,
  45         it first picks up any misaligned bytes, then words, before getting
  46         in the main loop that does the 8-byte clears.
  47
  48 --*/
  49 {
  50   UINT64 QWordValue;
  51   UINT64 MmxSave;
  52   __asm {
  53     mov edx, Count
  54     test edx, edx
  55     je _SetMemDone
  56
  57     push ebx
  58
  59     mov eax, Buffer
  60     mov bl, Value
  61     mov edi, eax
  62     mov bh, bl
  63
  64     cmp edx, 256
  65     jb _SetRemindingByte
  66
  67     and al, 07h
  68     test al, al
  69     je _SetBlock
  70
  71     mov eax, edi
  72     shr eax, 3
  73     inc eax
  74     shl eax, 3
  75     sub eax, edi
  76     cmp eax, edx
  77     jnb _SetRemindingByte
  78
  79     sub edx, eax
  80     mov ecx, eax
  81
  82     mov al, bl
  83     rep stosb
  84
  85 _SetBlock:
  86     mov eax, edx
  87     shr eax, 6
  88     test eax, eax
  89     je _SetRemindingByte
  90
  91     shl eax, 6
  92     sub edx, eax
  93     shr eax, 6
  94
  95     mov WORD PTR QWordValue[0], bx
  96     mov WORD PTR QWordValue[2], bx
  97     mov WORD PTR QWordValue[4], bx
  98     mov WORD PTR QWordValue[6], bx
  99
 100
 101     movq  MmxSave, mm0
 102     movq  mm0, QWordValue
 103
 104 _B:
 105     movq  QWORD PTR ds:[edi], mm0
 106     movq  QWORD PTR ds:[edi+8], mm0
 107     movq  QWORD PTR ds:[edi+16], mm0
 108     movq  QWORD PTR ds:[edi+24], mm0
 109     movq  QWORD PTR ds:[edi+32], mm0
 110     movq  QWORD PTR ds:[edi+40], mm0
 111     movq  QWORD PTR ds:[edi+48], mm0
 112     movq  QWORD PTR ds:[edi+56], mm0
 113     add edi, 64
 114     dec eax
 115     jnz _B
 116
 117 ; Restore mm0
 118     movq  mm0, MmxSave
 119     emms                                 ; Exit MMX Instruction
 120
 121 _SetRemindingByte:
 122     mov ecx, edx
 123
 124     mov eax, ebx
 125     shl eax, 16
 126     mov ax, bx
 127     shr ecx, 2
 128     rep stosd
 129
 130     mov ecx, edx
 131     and ecx, 3
 132     rep stosb
 133
 134     pop ebx
 135
 136 _SetMemDone:
 137
 138   }
 139 }