;------------------------------------------------------------------------------ | |
; | |
; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR> | |
; SPDX-License-Identifier: BSD-2-Clause-Patent | |
; | |
; Module Name: | |
; | |
; IsZeroBuffer.nasm | |
; | |
; Abstract: | |
; | |
; IsZeroBuffer function | |
; | |
; Notes: | |
; | |
;------------------------------------------------------------------------------ | |
SECTION .text | |
;------------------------------------------------------------------------------ | |
; BOOLEAN | |
; EFIAPI | |
; InternalMemIsZeroBuffer ( | |
; IN CONST VOID *Buffer, | |
; IN UINTN Length | |
; ); | |
;------------------------------------------------------------------------------ | |
global ASM_PFX(InternalMemIsZeroBuffer) | |
ASM_PFX(InternalMemIsZeroBuffer): | |
push edi | |
mov edi, [esp + 8] ; edi <- Buffer | |
mov ecx, [esp + 12] ; ecx <- Length | |
mov edx, ecx ; edx <- ecx | |
shr ecx, 2 ; ecx <- number of dwords | |
and edx, 3 ; edx <- number of trailing bytes | |
xor eax, eax ; eax <- 0, also set ZF | |
repe scasd | |
jnz @ReturnFalse ; ZF=0 means non-zero element found | |
mov ecx, edx | |
repe scasb | |
jnz @ReturnFalse | |
pop edi | |
mov eax, 1 ; return TRUE | |
ret | |
@ReturnFalse: | |
pop edi | |
xor eax, eax | |
ret ; return FALSE | |