;------------------------------------------------------------------------------
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;
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; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
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; SPDX-License-Identifier: BSD-2-Clause-Patent
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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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; CopyMem function
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;
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; Notes:
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;
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;------------------------------------------------------------------------------
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SECTION .text
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;------------------------------------------------------------------------------
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; VOID *
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; InternalMemCopyMem (
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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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global ASM_PFX(InternalMemCopyMem)
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ASM_PFX(InternalMemCopyMem):
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push esi
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push 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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lea eax, [esi + edx - 1] ; eax <- End of Source
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cmp esi, edi
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jae .0
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cmp eax, edi
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jae @CopyBackward ; Copy backward if overlapped
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.0:
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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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mov eax, [esp + 12] ; eax <- Destination as return value
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pop edi
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pop esi
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ret
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