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https://github.com/CloverHackyColor/CloverBootloader.git
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50 lines
1.5 KiB
NASM
50 lines
1.5 KiB
NASM
;------------------------------------------------------------------------------
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;
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; Copyright (c) 2016, 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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; IsZeroBuffer.nasm
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;
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; Abstract:
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;
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; IsZeroBuffer 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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; BOOLEAN
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; EFIAPI
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; InternalMemIsZeroBuffer (
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; IN CONST VOID *Buffer,
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; IN UINTN Length
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; );
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;------------------------------------------------------------------------------
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global ASM_PFX(InternalMemIsZeroBuffer)
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ASM_PFX(InternalMemIsZeroBuffer):
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push edi
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mov edi, [esp + 8] ; edi <- Buffer
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mov ecx, [esp + 12] ; ecx <- Length
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mov edx, ecx ; edx <- ecx
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shr ecx, 2 ; ecx <- number of dwords
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and edx, 3 ; edx <- number of trailing bytes
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xor eax, eax ; eax <- 0, also set ZF
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repe scasd
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jnz @ReturnFalse ; ZF=0 means non-zero element found
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mov ecx, edx
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repe scasb
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jnz @ReturnFalse
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pop edi
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mov eax, 1 ; return TRUE
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ret
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@ReturnFalse:
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pop edi
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xor eax, eax
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ret ; return FALSE
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