| ;------------------------------------------------------------------------------ | |
| ; | |
| ; 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 | |