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 ; CopyMem.asm 15 ; 16 ; Abstract: 17 ; 18 ; memcpy function 19 ; 20 ; Notes: 21 ; 22 ;------------------------------------------------------------------------------ 23 24 .code 25 26 ;------------------------------------------------------------------------------ 27 ; VOID * 28 ; memcpy ( 29 ; OUT VOID *DestinationBuffer, 30 ; IN CONST VOID *SourceBuffer, 31 ; IN UINTN Length 32 ; ); 33 ;------------------------------------------------------------------------------ 34 memcpy PROC USES rsi rdi 35 mov rax, rcx ; rax <- Destination as return value 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 <- Last byte of Source 43 cmp rsi, rdi 44 jae @F ; Copy forward if Source > Destination 45 cmp r9, rdi ; Overlapped? 46 jae @CopyBackward ; Copy backward if overlapped 47 @@: 48 xor rcx, rcx 49 sub rcx, rdi ; rcx <- -rdi 50 and rcx, 15 ; rcx + rsi should be 16 bytes aligned 51 jz @F ; skip if rcx == 0 52 cmp rcx, r8 53 cmova rcx, r8 54 sub r8, rcx 55 rep movsb 56 @@: 57 mov rcx, r8 58 and r8, 15 59 shr rcx, 4 ; rcx <- # of DQwords to copy 60 jz @CopyBytes 61 @@: 62 movdqu xmm0, [rsi] ; rsi may not be 16-byte aligned 63 movdqa [rdi], xmm0 ; rdi should be 16-byte aligned 64 add rsi, 16 65 add rdi, 16 66 loop @B 67 jmp @CopyBytes ; copy remaining bytes 68 @CopyBackward: 69 mov rsi, r9 ; rsi <- Last byte of Source 70 lea rdi, [rdi + r8 - 1] ; rdi <- Last byte of Destination 71 std 72 @CopyBytes: 73 mov rcx, r8 74 rep movsb 75 cld 76 @CopyMemDone: 77 ret 78 memcpy ENDP 79 80 END 81
