1;------------------------------------------------------------------------------
2;
3; Copyright (c) 2007, Intel Corporation. All rights reserved.<BR>
4; 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;   memcpyRep8.asm
15;
16; Abstract:
17;
18;   CopyMem function
19;
20; Notes:
21;
22;------------------------------------------------------------------------------
23
24    .code
25
26;------------------------------------------------------------------------------
27; VOID
28; memcpy (
29;   OUT     VOID                      *Destination,
30;   IN      VOID                      *Source,
31;   IN      UINTN                     Count
32;   );
33;------------------------------------------------------------------------------
34memcpy  PROC    USES    rsi rdi
35    mov     rax, rcx
36    cmp     rdx, rcx                    ; if Source == Destination, do nothing
37    je      @CopyMemDone
38    cmp     r8, 0                       ; if Count == 0, do nothing
39    je      @CopyMemDone
40    mov     rsi, rdx                    ; rsi <- Source
41    mov     rdi, rcx                    ; rdi <- Destination
42    lea     r9, [rsi + r8 - 1]          ; r9 <- End of Source
43    cmp     rsi, rdi
44    jae     @F
45    cmp     r9, rdi
46    jae     @CopyBackward               ; Copy backward if overlapped
47@@:
48    mov     rcx, r8
49    and     r8, 3
50    shr     rcx, 2
51    rep     movsd                       ; Copy as many Dwords as possible
52    jmp     @CopyBytes
53@CopyBackward:
54    mov     rsi, r9                     ; rsi <- End of Source
55    lea     rdi, [rdi + r8 - 1]         ; esi <- End of Destination
56    std                                 ; set direction flag
57@CopyBytes:
58    mov     rcx, r8
59    rep     movsb                       ; Copy bytes backward
60    cld
61@CopyMemDone:
62    ret
63memcpy  ENDP
64
65    END
66