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https://github.com/CloverHackyColor/CloverBootloader.git
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60 lines
1.7 KiB
NASM
60 lines
1.7 KiB
NASM
;------------------------------------------------------------------------------
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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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DEFAULT REL
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SECTION .text
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;------------------------------------------------------------------------------
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; VOID *
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; EFIAPI
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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 rsi
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push rdi
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mov rsi, rdx ; rsi <- Source
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mov rdi, rcx ; rdi <- Destination
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lea r9, [rsi + r8 - 1] ; r9 <- End of Source
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cmp rsi, rdi
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mov rax, rdi ; rax <- Destination as return value
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jae .0
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cmp r9, rdi
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jae @CopyBackward ; Copy backward if overlapped
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.0:
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mov rcx, r8
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and r8, 7
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shr rcx, 3
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rep movsq ; Copy as many Qwords as possible
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jmp @CopyBytes
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@CopyBackward:
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mov rsi, r9 ; rsi <- End of Source
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lea rdi, [rdi + r8 - 1] ; esi <- End of Destination
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std ; set direction flag
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@CopyBytes:
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mov rcx, r8
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rep movsb ; Copy bytes backward
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cld
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pop rdi
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pop rsi
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ret
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