VirtualBox

source: vbox/trunk/src/VBox/Runtime/common/asm/ASMMemFirstNonZero-generic.cpp@ 103795

Last change on this file since 103795 was 103010, checked in by vboxsync, 11 months ago

iprt/asm.h,*: Split out the ASMMem* and related stuff into a separate header, asm-mem.h, so
that we can get the RT_ASM_PAGE_SIZE stuff out of the way. [build fixes]

  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
File size: 2.7 KB
Line 
1/* $Id: ASMMemFirstNonZero-generic.cpp 103010 2024-01-24 00:14:44Z vboxsync $ */
2/** @file
3 * IPRT - ASMMemZeroPage - generic C implementation.
4 */
5
6/*
7 * Copyright (C) 2006-2023 Oracle and/or its affiliates.
8 *
9 * This file is part of VirtualBox base platform packages, as
10 * available from https://www.virtualbox.org.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation, in version 3 of the
15 * License.
16 *
17 * This program is distributed in the hope that it will be useful, but
18 * WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, see <https://www.gnu.org/licenses>.
24 *
25 * The contents of this file may alternatively be used under the terms
26 * of the Common Development and Distribution License Version 1.0
27 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28 * in the VirtualBox distribution, in which case the provisions of the
29 * CDDL are applicable instead of those of the GPL.
30 *
31 * You may elect to license modified versions of this file under the
32 * terms and conditions of either the GPL or the CDDL or both.
33 *
34 * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35 */
36
37
38/*********************************************************************************************************************************
39* Header Files *
40*********************************************************************************************************************************/
41#include <iprt/asm-mem.h>
42#include "internal/iprt.h"
43
44
45RTDECL(void RT_FAR *) ASMMemFirstNonZero(void const RT_FAR *pv, size_t cb) RT_NOTHROW_DEF
46{
47 uint8_t const *pb = (uint8_t const RT_FAR *)pv;
48
49 /*
50 * If we've got a large buffer to search, do it in larger units.
51 */
52 if (cb >= sizeof(size_t) * 2)
53 {
54 /* Align the pointer: */
55 while ((uintptr_t)pb & (sizeof(size_t) - 1))
56 {
57 if (RT_LIKELY(*pb == 0))
58 { /* likely */ }
59 else
60 return (void RT_FAR *)pb;
61 cb--;
62 pb++;
63 }
64
65 /* Scan in size_t sized words: */
66 while ( cb >= sizeof(size_t)
67 && *(size_t *)pb == 0)
68 {
69 pb += sizeof(size_t);
70 cb -= sizeof(size_t);
71 }
72 }
73
74 /*
75 * Search byte by byte.
76 */
77 for (; cb; cb--, pb++)
78 if (RT_LIKELY(*pb == 0))
79 { /* likely */ }
80 else
81 return (void RT_FAR *)pb;
82
83 return NULL;
84}
85
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