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;------------------------------------------------------------------------------ 34global ASM_PFX(InternalMemIsZeroBuffer) 35ASM_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