Update the copyright notice format

[mirror_edk2.git] / EdkCompatibilityPkg / Foundation / Library / EfiCommonLib / Ia32 / EfiZeroMem.c

/*++\r
\r
Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>\r
This program and the accompanying materials                          \r
are licensed and made available under the terms and conditions of the BSD License         \r
which accompanies this distribution.  The full text of the license may be found at        \r
http://opensource.org/licenses/bsd-license.php                                            \r
                                                                                          \r
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     \r
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             \r
\r
Module Name:\r
\r
  EfiZeroMem.c\r
\r
Abstract:\r
\r
  This is the code that supports IA32-optimized ZeroMem service\r
\r
--*/\r
\r
#include "Tiano.h"\r
\r
VOID\r
EfiCommonLibZeroMem (\r
  IN VOID   *Buffer,\r
  IN UINTN  Count\r
  )\r
/*++\r
\r
Input:  VOID   *Buffer - Pointer to buffer to clear\r
        UINTN  Count  - Number of bytes to clear\r
\r
Output: None.\r
\r
Saves:\r
\r
Modifies:\r
\r
Description:  This function is an optimized zero-memory function.\r
\r
Notes:  This function tries to zero memory 8 bytes at a time. As a result, \r
        it first picks up any misaligned bytes, then words, before getting \r
        in the main loop that does the 8-byte clears.\r
\r
--*/\r
{\r
  UINT64 MmxSave;\r
  __asm {\r
    mov   ecx, Count\r
    mov   edi, Buffer\r
\r
    ; Pick up misaligned start bytes (get pointer 4-byte aligned)\r
_StartByteZero:\r
    mov   eax, edi    \r
    and   al, 3                       ; check lower 2 bits of address\r
    test  al, al\r
    je    _ZeroBlocks                 ; already aligned?\r
    cmp   ecx, 0\r
    je    _ZeroMemDone\r
\r
    ; Clear the byte memory location\r
    mov   BYTE PTR [edi], 0           \r
    inc    edi\r
\r
    ; Decrement our count\r
    dec    ecx\r
    jmp   _StartByteZero        ; back to top of loop\r
\r
_ZeroBlocks:\r
\r
    ; Compute how many 64-byte blocks we can clear \r
    mov   edx, ecx\r
    shr   ecx, 6                      ; convert to 64-byte count\r
    shl   ecx, 6                      ; convert back to bytes\r
    sub   edx, ecx                    ; subtract from the original count\r
    shr   ecx, 6                      ; and this is how many 64-byte blocks\r
\r
    ; If no 64-byte blocks, then skip \r
    cmp    ecx, 0\r
    je    _ZeroRemaining\r
\r
    ; Save mm0\r
    movq  MmxSave, mm0\r
\r
    pxor  mm0, mm0          ; Clear mm0\r
\r
_B:\r
    movq  QWORD PTR ds:[edi], mm0\r
    movq  QWORD PTR ds:[edi+8], mm0\r
    movq  QWORD PTR ds:[edi+16], mm0\r
    movq  QWORD PTR ds:[edi+24], mm0\r
    movq  QWORD PTR ds:[edi+32], mm0\r
    movq  QWORD PTR ds:[edi+40], mm0\r
    movq  QWORD PTR ds:[edi+48], mm0\r
    movq  QWORD PTR ds:[edi+56], mm0\r
   \r
    add    edi, 64\r
    dec    ecx\r
    jnz    _B\r
  \r
; Restore mm0\r
    movq  mm0, MmxSave\r
    emms                                 ; Exit MMX Instruction\r
\r
_ZeroRemaining:\r
    ; Zero out as many DWORDS as possible\r
    mov   ecx, edx\r
    shr   ecx, 2\r
    xor   eax, eax\r
\r
    rep stosd\r
\r
    ; Zero out remaining as bytes\r
    mov   ecx, edx\r
    and   ecx, 03\r
\r
    rep   stosb\r
 \r
_ZeroMemDone:\r
  }\r
}\r