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02b5cf7f HW |
1 | ;------------------------------------------------------------------------------\r |
2 | ;\r | |
3 | ; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>\r | |
9344f092 | 4 | ; SPDX-License-Identifier: BSD-2-Clause-Patent\r |
02b5cf7f HW |
5 | ;\r |
6 | ; Module Name:\r | |
7 | ;\r | |
8 | ; IsZeroBuffer.nasm\r | |
9 | ;\r | |
10 | ; Abstract:\r | |
11 | ;\r | |
12 | ; IsZeroBuffer function\r | |
13 | ;\r | |
14 | ; Notes:\r | |
15 | ;\r | |
16 | ;------------------------------------------------------------------------------\r | |
17 | \r | |
18 | SECTION .text\r | |
19 | \r | |
20 | ;------------------------------------------------------------------------------\r | |
21 | ; BOOLEAN\r | |
22 | ; EFIAPI\r | |
23 | ; InternalMemIsZeroBuffer (\r | |
24 | ; IN CONST VOID *Buffer,\r | |
25 | ; IN UINTN Length\r | |
26 | ; );\r | |
27 | ;------------------------------------------------------------------------------\r | |
28 | global ASM_PFX(InternalMemIsZeroBuffer)\r | |
29 | ASM_PFX(InternalMemIsZeroBuffer):\r | |
30 | push edi\r | |
31 | mov edi, [esp + 8] ; edi <- Buffer\r | |
32 | mov ecx, [esp + 12] ; ecx <- Length\r | |
33 | mov edx, ecx ; edx <- ecx\r | |
34 | shr ecx, 2 ; ecx <- number of dwords\r | |
35 | and edx, 3 ; edx <- number of trailing bytes\r | |
36 | xor eax, eax ; eax <- 0, also set ZF\r | |
37 | repe scasd\r | |
38 | jnz @ReturnFalse ; ZF=0 means non-zero element found\r | |
39 | mov ecx, edx\r | |
40 | repe scasb\r | |
41 | jnz @ReturnFalse\r | |
42 | pop edi\r | |
43 | mov eax, 1 ; return TRUE\r | |
44 | ret\r | |
45 | @ReturnFalse:\r | |
46 | pop edi\r | |
47 | xor eax, eax\r | |
48 | ret ; return FALSE\r | |
49 | \r |