1 ;------------------------------------------------------------------------------ 2 ; 3 ; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR> 4 ; This program and the accompanying materials 5 ; are licensed and made available under the terms and conditions of the BSD License 6 ; which accompanies this distribution. The full text of the license may be found at 7 ; http://opensource.org/licenses/bsd-license.php. 8 ; 9 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 10 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 11 ; 12 ; Module Name: 13 ; 14 ; IsZeroBuffer.nasm 15 ; 16 ; Abstract: 17 ; 18 ; IsZeroBuffer function 19 ; 20 ; Notes: 21 ; 22 ;------------------------------------------------------------------------------ 23 24 SECTION .text 25 26 ;------------------------------------------------------------------------------ 27 ; BOOLEAN 28 ; EFIAPI 29 ; InternalMemIsZeroBuffer ( 30 ; IN CONST VOID *Buffer, 31 ; IN UINTN Length 32 ; ); 33 ;------------------------------------------------------------------------------ 34 global ASM_PFX(InternalMemIsZeroBuffer) 35 ASM_PFX(InternalMemIsZeroBuffer): 36 push edi 37 mov edi, [esp + 8] ; edi <- Buffer 38 mov ecx, [esp + 12] ; ecx <- Length 39 mov edx, ecx ; edx <- ecx 40 shr ecx, 2 ; ecx <- number of dwords 41 and edx, 3 ; edx <- number of trailing bytes 42 xor eax, eax ; eax <- 0, also set ZF 43 repe scasd 44 jnz @ReturnFalse ; ZF=0 means non-zero element found 45 mov ecx, edx 46 repe scasb 47 jnz @ReturnFalse 48 pop edi 49 mov eax, 1 ; return TRUE 50 ret 51 @ReturnFalse: 52 pop edi 53 xor eax, eax 54 ret ; return FALSE 55 56
