VirtualBox

source: vbox/trunk/src/VBox/Runtime/common/asm/ASMMemFirstNonZero-generic.cpp@ 93943

Last change on this file since 93943 was 93115, checked in by vboxsync, 3 years ago

scm --update-copyright-year

  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
File size: 2.4 KB
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1/* $Id: ASMMemFirstNonZero-generic.cpp 93115 2022-01-01 11:31:46Z vboxsync $ */
2/** @file
3 * IPRT - ASMMemZeroPage - generic C implementation.
4 */
5
6/*
7 * Copyright (C) 2006-2022 Oracle Corporation
8 *
9 * This file is part of VirtualBox Open Source Edition (OSE), as
10 * available from http://www.virtualbox.org. This file is free software;
11 * you can redistribute it and/or modify it under the terms of the GNU
12 * General Public License (GPL) as published by the Free Software
13 * Foundation, in version 2 as it comes in the "COPYING" file of the
14 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16 *
17 * The contents of this file may alternatively be used under the terms
18 * of the Common Development and Distribution License Version 1.0
19 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20 * VirtualBox OSE distribution, in which case the provisions of the
21 * CDDL are applicable instead of those of the GPL.
22 *
23 * You may elect to license modified versions of this file under the
24 * terms and conditions of either the GPL or the CDDL or both.
25 */
26
27
28/*********************************************************************************************************************************
29* Header Files *
30*********************************************************************************************************************************/
31#include <iprt/asm.h>
32#include "internal/iprt.h"
33
34
35RTDECL(void RT_FAR *) ASMMemFirstNonZero(void const RT_FAR *pv, size_t cb) RT_NOTHROW_DEF
36{
37 uint8_t const *pb = (uint8_t const RT_FAR *)pv;
38
39 /*
40 * If we've got a large buffer to search, do it in larger units.
41 */
42 if (cb >= sizeof(size_t) * 2)
43 {
44 /* Align the pointer: */
45 while ((uintptr_t)pb & (sizeof(size_t) - 1))
46 {
47 if (RT_LIKELY(*pb == 0))
48 { /* likely */ }
49 else
50 return (void RT_FAR *)pb;
51 cb--;
52 pb++;
53 }
54
55 /* Scan in size_t sized words: */
56 while ( cb >= sizeof(size_t)
57 && *(size_t *)pb == 0)
58 {
59 pb += sizeof(size_t);
60 cb -= sizeof(size_t);
61 }
62 }
63
64 /*
65 * Search byte by byte.
66 */
67 for (; cb; cb--, pb++)
68 if (RT_LIKELY(*pb == 0))
69 { /* likely */ }
70 else
71 return (void RT_FAR *)pb;
72
73 return NULL;
74}
75
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