You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
77 lines
2.6 KiB
77 lines
2.6 KiB
4 years ago
|
;------------------------------------------------------------------------------
|
||
|
|
;
|
||
|
|
; 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
|
||
|
|
xor rcx, rcx ; rcx <- 0
|
||
|
|
sub rcx, rdi
|
||
|
|
and rcx, 15 ; rcx + rdi aligns on 16-byte boundary
|
||
|
|
jz @Is16BytesZero
|
||
|
|
cmp rcx, rdx ; Length already in rdx
|
||
|
|
cmova rcx, rdx ; bytes before the 16-byte boundary
|
||
|
|
sub rdx, rcx
|
||
|
|
xor rax, rax ; rax <- 0, also set ZF
|
||
|
|
repe scasb
|
||
|
|
jnz @ReturnFalse ; ZF=0 means non-zero element found
|
||
|
|
@Is16BytesZero:
|
||
|
|
mov rcx, rdx
|
||
|
|
and rdx, 15
|
||
|
|
shr rcx, 4
|
||
|
|
jz @IsBytesZero
|
||
|
|
.0:
|
||
|
|
pxor xmm0, xmm0 ; xmm0 <- 0
|
||
|
|
pcmpeqb xmm0, [rdi] ; check zero for 16 bytes
|
||
|
|
pmovmskb eax, xmm0 ; eax <- compare results
|
||
|
|
; nasm doesn't support 64-bit destination
|
||
|
|
; for pmovmskb
|
||
|
|
cmp eax, 0xffff
|
||
|
|
jnz @ReturnFalse
|
||
|
|
add rdi, 16
|
||
|
|
loop .0
|
||
|
|
@IsBytesZero:
|
||
|
|
mov rcx, rdx
|
||
|
|
xor rax, rax ; rax <- 0, also set ZF
|
||
|
|
repe scasb
|
||
|
|
jnz @ReturnFalse ; ZF=0 means non-zero element found
|
||
|
|
pop rdi
|
||
|
|
mov rax, 1 ; return TRUE
|
||
|
|
ret
|
||
|
|
@ReturnFalse:
|
||
|
|
pop rdi
|
||
|
|
xor rax, rax
|
||
|
|
ret ; return FALSE
|
||
|
|
|