Initial import.

[mirror_edk2.git] / MdePkg / Library / BaseMemoryLibRepStr / Ia32 / CopyMem.asm

;------------------------------------------------------------------------------\r
;\r
; Copyright (c) 2006, Intel Corporation\r
; All rights reserved. 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
;   CopyMem.Asm\r
;\r
; Abstract:\r
;\r
;   CopyMem function\r
;\r
; Notes:\r
;\r
;------------------------------------------------------------------------------\r
\r
    .386\r
    .model  flat,C\r
    .code\r
\r
InternalMemCopyMem  PROC    USES    esi edi\r
    mov     esi, [esp + 16]             ; esi <- Source\r
    mov     edi, [esp + 12]             ; edi <- Destination\r
    mov     edx, [esp + 20]             ; edx <- Count\r
    lea     eax, [edi + edx - 1]        ; eax <- End of Destination\r
    cmp     esi, edi\r
    jae     @F\r
    cmp     eax, esi\r
    jae     @CopyBackward               ; Copy backward if overlapped\r
@@:\r
    mov     ecx, edx\r
    and     edx, 3\r
    shr     ecx, 2\r
    rep     movsd                       ; Copy as many Dwords as possible\r
    jmp     @CopyBytes\r
@CopyBackward:\r
    mov     edi, eax                    ; edi <- End of Destination\r
    lea     esi, [esi + edx - 1]        ; esi <- End of Source\r
    std\r
@CopyBytes:\r
    mov     ecx, edx\r
    rep     movsb                       ; Copy bytes backward\r
    cld\r
    mov     eax, [esp + 12]             ; eax <- Destination as return value\r
    ret\r
InternalMemCopyMem  ENDP\r
\r
    END\r