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MdePkg BaseMemoryLibRepStr: Convert X64/CopyMem.asm to NASM
[mirror_edk2.git] / MdePkg / Library / BaseMemoryLibRepStr / X64 / CopyMem.nasm
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1;------------------------------------------------------------------------------\r
2;\r
3; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>\r
4; This program and the accompanying materials\r
5; are licensed and made available under the terms and conditions of the BSD License\r
6; which accompanies this distribution. The full text of the license may be found at\r
7; http://opensource.org/licenses/bsd-license.php.\r
8;\r
9; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
10; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
11;\r
12; Module Name:\r
13;\r
14; CopyMem.Asm\r
15;\r
16; Abstract:\r
17;\r
18; CopyMem function\r
19;\r
20; Notes:\r
21;\r
22;------------------------------------------------------------------------------\r
23\r
24 DEFAULT REL\r
25 SECTION .text\r
26\r
27;------------------------------------------------------------------------------\r
28; VOID *\r
29; EFIAPI\r
30; InternalMemCopyMem (\r
31; IN VOID *Destination,\r
32; IN VOID *Source,\r
33; IN UINTN Count\r
34; )\r
35;------------------------------------------------------------------------------\r
36global ASM_PFX(InternalMemCopyMem)\r
37ASM_PFX(InternalMemCopyMem):\r
38 push rsi\r
39 push rdi\r
40 mov rsi, rdx ; rsi <- Source\r
41 mov rdi, rcx ; rdi <- Destination\r
42 lea r9, [rsi + r8 - 1] ; r9 <- End of Source\r
43 cmp rsi, rdi\r
44 mov rax, rdi ; rax <- Destination as return value\r
45 jae .0\r
46 cmp r9, rdi\r
47 jae @CopyBackward ; Copy backward if overlapped\r
48.0:\r
49 mov rcx, r8\r
50 and r8, 7\r
51 shr rcx, 3\r
52 rep movsq ; Copy as many Qwords as possible\r
53 jmp @CopyBytes\r
54@CopyBackward:\r
55 mov rsi, r9 ; rsi <- End of Source\r
56 lea rdi, [rdi + r8 - 1] ; esi <- End of Destination\r
57 std ; set direction flag\r
58@CopyBytes:\r
59 mov rcx, r8\r
60 rep movsb ; Copy bytes backward\r
61 cld\r
62 pop rdi\r
63 pop rsi\r
64 ret\r
65\r