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;------------------------------------------------------------------------------
;
; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
; Module Name:
;
; IsZeroBuffer.nasm
;
; Abstract:
;
; IsZeroBuffer function
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; BOOLEAN
; EFIAPI
; InternalMemIsZeroBuffer (
; IN CONST VOID *Buffer,
; IN UINTN Length
; );
;------------------------------------------------------------------------------
global ASM_PFX(InternalMemIsZeroBuffer)
ASM_PFX(InternalMemIsZeroBuffer):
push rdi
mov rdi, rcx ; rdi <- Buffer
mov rcx, rdx ; rcx <- Length
shr rcx, 3 ; rcx <- number of qwords
and rdx, 7 ; rdx <- number of trailing bytes
xor rax, rax ; rax <- 0, also set ZF
repe scasq
jnz @ReturnFalse ; ZF=0 means non-zero element found
mov rcx, rdx
repe scasb
jnz @ReturnFalse
pop rdi
mov rax, 1 ; return TRUE
ret
@ReturnFalse:
pop rdi
xor rax, rax
ret ; return FALSE
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