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 ;------------------------------------------------------------------------------ 34 memcpy 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, 7 50 shr rcx, 3 51 rep movsq ; Copy as many Qwords 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 63 memcpy ENDP 64 65 END 66 67
