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;------------------------------------------------------------------------------
;
; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
; This program and the accompanying materials
; are licensed and made available under the terms and conditions of the BSD License
; which accompanies this distribution. The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php.
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;
; 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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