[21914] | 1 | /* $Id: adler32.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - Adler-32
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| 4 | */
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| 5 |
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| 6 | /*
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[98103] | 7 | * Copyright (C) 2009-2023 Oracle and/or its affiliates.
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[21914] | 8 | *
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[96407] | 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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[21914] | 11 | *
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[96407] | 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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[21914] | 25 | * The contents of this file may alternatively be used under the terms
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| 26 | * of the Common Development and Distribution License Version 1.0
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[96407] | 27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | * in the VirtualBox distribution, in which case the provisions of the
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[21914] | 29 | * CDDL are applicable instead of those of the GPL.
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| 30 | *
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| 31 | * You may elect to license modified versions of this file under the
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| 32 | * terms and conditions of either the GPL or the CDDL or both.
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[96407] | 33 | *
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| 34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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[21914] | 35 | */
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| 36 |
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| 37 |
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[57358] | 38 | /*********************************************************************************************************************************
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| 39 | * Header Files *
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| 40 | *********************************************************************************************************************************/
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[21914] | 41 | #include <iprt/crc.h>
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| 42 | #include "internal/iprt.h"
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| 43 |
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| 44 | #include <iprt/asm.h>
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| 45 | #include <iprt/assert.h>
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| 46 |
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| 47 |
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[57358] | 48 | /*********************************************************************************************************************************
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| 49 | * Defined Constants And Macros *
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| 50 | *********************************************************************************************************************************/
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[21914] | 51 | #define RTCRC_ADLER_32_NUMBER 65521
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| 52 |
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| 53 |
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| 54 | RTDECL(uint32_t) RTCrcAdler32(void const *pv, size_t cb)
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| 55 | {
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| 56 | /* Don't want to do the unrolling twice. */
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| 57 | return RTCrcAdler32Process(RTCrcAdler32Start(), pv, cb);
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| 58 | }
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| 59 |
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| 60 |
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| 61 | RTDECL(uint32_t) RTCrcAdler32Start(void)
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| 62 | {
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| 63 | return 1;
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| 64 | }
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| 65 |
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| 66 |
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| 67 | RTDECL(uint32_t) RTCrcAdler32Process(uint32_t u32Crc, void const *pv, size_t cb)
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| 68 | {
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| 69 | uint8_t const *pbSrc = (uint8_t const *)pv;
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| 70 | uint32_t a = u32Crc & 0xffff;
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| 71 | uint32_t b = u32Crc >> 16;
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| 72 | if (cb < 64 /* randomly selected number */)
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| 73 | {
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| 74 | while (cb-- > 0)
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| 75 | {
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| 76 | a += *pbSrc++;
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| 77 | a %= RTCRC_ADLER_32_NUMBER;
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| 78 | b += a;
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| 79 | b %= RTCRC_ADLER_32_NUMBER;
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| 80 | }
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| 81 | }
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| 82 | else
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| 83 | {
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| 84 | switch (((uintptr_t)pbSrc & 0x3))
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| 85 | {
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| 86 | case 0:
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| 87 | break;
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| 88 |
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| 89 | case 1:
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| 90 | a += *pbSrc++;
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| 91 | a %= RTCRC_ADLER_32_NUMBER;
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| 92 | b += a;
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| 93 | b %= RTCRC_ADLER_32_NUMBER;
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| 94 | cb--;
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[69046] | 95 | RT_FALL_THRU();
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[21914] | 96 |
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| 97 | case 2:
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| 98 | a += *pbSrc++;
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| 99 | a %= RTCRC_ADLER_32_NUMBER;
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| 100 | b += a;
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| 101 | b %= RTCRC_ADLER_32_NUMBER;
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| 102 | cb--;
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[69046] | 103 | RT_FALL_THRU();
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[21914] | 104 |
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| 105 | case 3:
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| 106 | a += *pbSrc++;
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| 107 | a %= RTCRC_ADLER_32_NUMBER;
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| 108 | b += a;
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| 109 | b %= RTCRC_ADLER_32_NUMBER;
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| 110 | cb--;
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| 111 | break;
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| 112 | }
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| 113 |
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| 114 | while (cb >= 4)
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| 115 | {
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| 116 | uint32_t u32 = *(uint32_t const *)pbSrc;
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| 117 | pbSrc += 4;
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| 118 |
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| 119 | a += u32 & 0xff;
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| 120 | a %= RTCRC_ADLER_32_NUMBER;
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| 121 | b += a;
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| 122 | b %= RTCRC_ADLER_32_NUMBER;
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| 123 |
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| 124 | a += (u32 >> 8) & 0xff;
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| 125 | a %= RTCRC_ADLER_32_NUMBER;
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| 126 | b += a;
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| 127 | b %= RTCRC_ADLER_32_NUMBER;
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| 128 |
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| 129 | a += (u32 >> 16) & 0xff;
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| 130 | a %= RTCRC_ADLER_32_NUMBER;
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| 131 | b += a;
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| 132 | b %= RTCRC_ADLER_32_NUMBER;
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| 133 |
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| 134 | a += (u32 >> 24) & 0xff;
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| 135 | a %= RTCRC_ADLER_32_NUMBER;
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| 136 | b += a;
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| 137 | b %= RTCRC_ADLER_32_NUMBER;
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| 138 |
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| 139 | cb -= 4;
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| 140 | }
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| 141 |
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| 142 | switch (cb)
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| 143 | {
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| 144 | case 0:
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| 145 | break;
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| 146 |
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| 147 | case 3:
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| 148 | a += *pbSrc++;
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| 149 | a %= RTCRC_ADLER_32_NUMBER;
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| 150 | b += a;
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| 151 | b %= RTCRC_ADLER_32_NUMBER;
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| 152 | cb--;
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[69046] | 153 | RT_FALL_THRU();
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[21914] | 154 |
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| 155 | case 2:
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| 156 | a += *pbSrc++;
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| 157 | a %= RTCRC_ADLER_32_NUMBER;
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| 158 | b += a;
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| 159 | b %= RTCRC_ADLER_32_NUMBER;
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| 160 | cb--;
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[69046] | 161 | RT_FALL_THRU();
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[21914] | 162 |
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| 163 | case 1:
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| 164 | a += *pbSrc++;
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| 165 | a %= RTCRC_ADLER_32_NUMBER;
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| 166 | b += a;
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| 167 | b %= RTCRC_ADLER_32_NUMBER;
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| 168 | cb--;
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| 169 | break;
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| 170 | }
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| 171 | }
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| 172 |
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| 173 | return a | (b << 16);
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| 174 | }
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| 175 |
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| 176 |
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| 177 | RTDECL(uint32_t) RTCrcAdler32Finish(uint32_t u32Crc)
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| 178 | {
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| 179 | return u32Crc;
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| 180 | }
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| 181 |
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