mirror of https://github.com/acidanthera/audk.git
71 lines
2.0 KiB
NASM
71 lines
2.0 KiB
NASM
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;------------------------------------------------------------------------------
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;
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; Copyright (c) 2007, Intel Corporation
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; All rights reserved. This program and the accompanying materials
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; are licensed and made available under the terms and conditions of the BSD License
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; which accompanies this distribution. The full text of the license may be found at
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; http://opensource.org/licenses/bsd-license.php
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;
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; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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;
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; Module Name:
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;
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; CopyMem.asm
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;
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; Abstract:
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;
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; memcpy function
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;
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; Notes:
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;
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;------------------------------------------------------------------------------
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.686
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.model flat,C
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.mmx
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.code
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;------------------------------------------------------------------------------
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; VOID *
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; memcpy (
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; IN VOID *Destination,
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; IN VOID *Source,
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; IN UINTN Count
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; );
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;------------------------------------------------------------------------------
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memcpy PROC USES esi edi
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mov esi, [esp + 16] ; esi <- Source
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mov edi, [esp + 12] ; edi <- Destination
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mov edx, [esp + 20] ; edx <- Count
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cmp esi, edi
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je @CopyDone
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cmp edx, 0
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je @CopyDone
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lea eax, [esi + edx - 1] ; eax <- End of Source
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cmp esi, edi
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jae @F
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cmp eax, edi
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jae @CopyBackward ; Copy backward if overlapped
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@@:
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mov ecx, edx
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and edx, 3
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shr ecx, 2
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rep movsd ; Copy as many Dwords as possible
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jmp @CopyBytes
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@CopyBackward:
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mov esi, eax ; esi <- End of Source
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lea edi, [edi + edx - 1] ; edi <- End of Destination
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std
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@CopyBytes:
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mov ecx, edx
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rep movsb ; Copy bytes backward
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cld
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@CopyDone:
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mov eax, [esp + 12]
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ret
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memcpy ENDP
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END
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