-| | | 1 | | // Adler32.cs - Computes Adler32 data checksum of a data stream |
-| | | 2 | | // Copyright © 2000-2016 AlphaSierraPapa for the SharpZipLib Team |
-| | | 3 | | // |
-| | | 4 | | // This file was translated from java, it was part of the GNU Classpath |
-| | | 5 | | // Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc. |
-| | | 6 | | // |
-| | | 7 | | // This program is free software; you can redistribute it and/or |
-| | | 8 | | // modify it under the terms of the GNU General Public License |
-| | | 9 | | // as published by the Free Software Foundation; either version 2 |
-| | | 10 | | // of the License, or (at your option) any later version. |
-| | | 11 | | // |
-| | | 12 | | // This program is distributed in the hope that it will be useful, |
-| | | 13 | | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
-| | | 14 | | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
-| | | 15 | | // GNU General Public License for more details. |
-| | | 16 | | // |
-| | | 17 | | // You should have received a copy of the GNU General Public License |
-| | | 18 | | // along with this program; if not, write to the Free Software |
-| | | 19 | | // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
-| | | 20 | | // |
-| | | 21 | | // Linking this library statically or dynamically with other modules is |
-| | | 22 | | // making a combined work based on this library. Thus, the terms and |
-| | | 23 | | // conditions of the GNU General Public License cover the whole |
-| | | 24 | | // combination. |
-| | | 25 | | // |
-| | | 26 | | // As a special exception, the copyright holders of this library give you |
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-| | | 28 | | // executable, regardless of the license terms of these independent |
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-| | | 31 | | // independent module, the terms and conditions of the license of that |
-| | | 32 | | // module. An independent module is a module which is not derived from |
-| | | 33 | | // or based on this library. If you modify this library, you may extend |
-| | | 34 | | // this exception to your version of the library, but you are not |
-| | | 35 | | // obligated to do so. If you do not wish to do so, delete this |
-| | | 36 | | // exception statement from your version. |
-| | | 37 | | |
-| | | 38 | | using System; |
-| | | 39 | | |
-| | | 40 | | namespace ICSharpCode.SharpZipLib.Checksums |
-| | | 41 | | { |
-| | | 42 | | |
-| | | 43 | | /// <summary> |
-| | | 44 | | /// Computes Adler32 checksum for a stream of data. An Adler32 |
-| | | 45 | | /// checksum is not as reliable as a CRC32 checksum, but a lot faster to |
-| | | 46 | | /// compute. |
-| | | 47 | | /// |
-| | | 48 | | /// The specification for Adler32 may be found in RFC 1950. |
-| | | 49 | | /// ZLIB Compressed Data Format Specification version 3.3) |
-| | | 50 | | /// |
-| | | 51 | | /// |
-| | | 52 | | /// From that document: |
-| | | 53 | | /// |
-| | | 54 | | /// "ADLER32 (Adler-32 checksum) |
-| | | 55 | | /// This contains a checksum value of the uncompressed data |
-| | | 56 | | /// (excluding any dictionary data) computed according to Adler-32 |
-| | | 57 | | /// algorithm. This algorithm is a 32-bit extension and improvement |
-| | | 58 | | /// of the Fletcher algorithm, used in the ITU-T X.224 / ISO 8073 |
-| | | 59 | | /// standard. |
-| | | 60 | | /// |
-| | | 61 | | /// Adler-32 is composed of two sums accumulated per byte: s1 is |
-| | | 62 | | /// the sum of all bytes, s2 is the sum of all s1 values. Both sums |
-| | | 63 | | /// are done modulo 65521. s1 is initialized to 1, s2 to zero. The |
-| | | 64 | | /// Adler-32 checksum is stored as s2*65536 + s1 in most- |
-| | | 65 | | /// significant-byte first (network) order." |
-| | | 66 | | /// |
-| | | 67 | | /// "8.2. The Adler-32 algorithm |
-| | | 68 | | /// |
-| | | 69 | | /// The Adler-32 algorithm is much faster than the CRC32 algorithm yet |
-| | | 70 | | /// still provides an extremely low probability of undetected errors. |
-| | | 71 | | /// |
-| | | 72 | | /// The modulo on unsigned long accumulators can be delayed for 5552 |
-| | | 73 | | /// bytes, so the modulo operation time is negligible. If the bytes |
-| | | 74 | | /// are a, b, c, the second sum is 3a + 2b + c + 3, and so is position |
-| | | 75 | | /// and order sensitive, unlike the first sum, which is just a |
-| | | 76 | | /// checksum. That 65521 is prime is important to avoid a possible |
-| | | 77 | | /// large class of two-byte errors that leave the check unchanged. |
-| | | 78 | | /// (The Fletcher checksum uses 255, which is not prime and which also |
-| | | 79 | | /// makes the Fletcher check insensitive to single byte changes 0 - |
-| | | 80 | | /// 255.) |
-| | | 81 | | /// |
-| | | 82 | | /// The sum s1 is initialized to 1 instead of zero to make the length |
-| | | 83 | | /// of the sequence part of s2, so that the length does not have to be |
-| | | 84 | | /// checked separately. (Any sequence of zeroes has a Fletcher |
-| | | 85 | | /// checksum of zero.)" |
-| | | 86 | | /// </summary> |
-| | | 87 | | /// <see cref="ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream"/> |
-| | | 88 | | /// <see cref="ICSharpCode.SharpZipLib.Zip.Compression.Streams.DeflaterOutputStream"/> |
-| | | 89 | | public sealed class Adler32 : IChecksum |
-| | | 90 | | { |
-| | | 91 | | /// <summary> |
-| | | 92 | | /// largest prime smaller than 65536 |
-| | | 93 | | /// </summary> |
-| | | 94 | | const uint BASE = 65521; |
-| | | 95 | | |
-| | | 96 | | /// <summary> |
-| | | 97 | | /// Returns the Adler32 data checksum computed so far. |
-| | | 98 | | /// </summary> |
-| | | 99 | | public long Value { |
-| | | 100 | | get { |
-| | 15 | 101 | | return checksum; |
-| | | 102 | | } |
-| | | 103 | | } |
-| | | 104 | | |
-| | | 105 | | /// <summary> |
-| | | 106 | | /// Creates a new instance of the Adler32 class. |
-| | | 107 | | /// The checksum starts off with a value of 1. |
-| | | 108 | | /// </summary> |
-| | 720 | 109 | | public Adler32() |
-| | | 110 | | { |
-| | 720 | 111 | | Reset(); |
-| | 720 | 112 | | } |
-| | | 113 | | |
-| | | 114 | | /// <summary> |
-| | | 115 | | /// Resets the Adler32 checksum to the initial value. |
-| | | 116 | | /// </summary> |
-| | | 117 | | public void Reset() |
-| | | 118 | | { |
-| | 1165 | 119 | | checksum = 1; |
-| | 1165 | 120 | | } |
-| | | 121 | | |
-| | | 122 | | /// <summary> |
-| | | 123 | | /// Updates the checksum with a byte value. |
-| | | 124 | | /// </summary> |
-| | | 125 | | /// <param name="value"> |
-| | | 126 | | /// The data value to add. The high byte of the int is ignored. |
-| | | 127 | | /// </param> |
-| | | 128 | | public void Update(int value) |
-| | | 129 | | { |
-| | | 130 | | // We could make a length 1 byte array and call update again, but I |
-| | | 131 | | // would rather not have that overhead |
-| | 0 | 132 | | uint s1 = checksum & 0xFFFF; |
-| | 0 | 133 | | uint s2 = checksum >> 16; |
+| | | 1 | | using System; |
+| | | 2 | | |
+| | | 3 | | namespace ICSharpCode.SharpZipLib.Checksum |
+| | | 4 | | { |
+| | | 5 | | /// <summary> |
+| | | 6 | | /// Computes Adler32 checksum for a stream of data. An Adler32 |
+| | | 7 | | /// checksum is not as reliable as a CRC32 checksum, but a lot faster to |
+| | | 8 | | /// compute. |
+| | | 9 | | /// |
+| | | 10 | | /// The specification for Adler32 may be found in RFC 1950. |
+| | | 11 | | /// ZLIB Compressed Data Format Specification version 3.3) |
+| | | 12 | | /// |
+| | | 13 | | /// |
+| | | 14 | | /// From that document: |
+| | | 15 | | /// |
+| | | 16 | | /// "ADLER32 (Adler-32 checksum) |
+| | | 17 | | /// This contains a checksum value of the uncompressed data |
+| | | 18 | | /// (excluding any dictionary data) computed according to Adler-32 |
+| | | 19 | | /// algorithm. This algorithm is a 32-bit extension and improvement |
+| | | 20 | | /// of the Fletcher algorithm, used in the ITU-T X.224 / ISO 8073 |
+| | | 21 | | /// standard. |
+| | | 22 | | /// |
+| | | 23 | | /// Adler-32 is composed of two sums accumulated per byte: s1 is |
+| | | 24 | | /// the sum of all bytes, s2 is the sum of all s1 values. Both sums |
+| | | 25 | | /// are done modulo 65521. s1 is initialized to 1, s2 to zero. The |
+| | | 26 | | /// Adler-32 checksum is stored as s2*65536 + s1 in most- |
+| | | 27 | | /// significant-byte first (network) order." |
+| | | 28 | | /// |
+| | | 29 | | /// "8.2. The Adler-32 algorithm |
+| | | 30 | | /// |
+| | | 31 | | /// The Adler-32 algorithm is much faster than the CRC32 algorithm yet |
+| | | 32 | | /// still provides an extremely low probability of undetected errors. |
+| | | 33 | | /// |
+| | | 34 | | /// The modulo on unsigned long accumulators can be delayed for 5552 |
+| | | 35 | | /// bytes, so the modulo operation time is negligible. If the bytes |
+| | | 36 | | /// are a, b, c, the second sum is 3a + 2b + c + 3, and so is position |
+| | | 37 | | /// and order sensitive, unlike the first sum, which is just a |
+| | | 38 | | /// checksum. That 65521 is prime is important to avoid a possible |
+| | | 39 | | /// large class of two-byte errors that leave the check unchanged. |
+| | | 40 | | /// (The Fletcher checksum uses 255, which is not prime and which also |
+| | | 41 | | /// makes the Fletcher check insensitive to single byte changes 0 - |
+| | | 42 | | /// 255.) |
+| | | 43 | | /// |
+| | | 44 | | /// The sum s1 is initialized to 1 instead of zero to make the length |
+| | | 45 | | /// of the sequence part of s2, so that the length does not have to be |
+| | | 46 | | /// checked separately. (Any sequence of zeroes has a Fletcher |
+| | | 47 | | /// checksum of zero.)" |
+| | | 48 | | /// </summary> |
+| | | 49 | | /// <see cref="ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream"/> |
+| | | 50 | | /// <see cref="ICSharpCode.SharpZipLib.Zip.Compression.Streams.DeflaterOutputStream"/> |
+| | | 51 | | public sealed class Adler32 : IChecksum |
+| | | 52 | | { |
+| | | 53 | | #region Instance Fields |
+| | | 54 | | /// <summary> |
+| | | 55 | | /// largest prime smaller than 65536 |
+| | | 56 | | /// </summary> |
+| | 1 | 57 | | readonly static uint BASE = 65521; |
+| | | 58 | | |
+| | | 59 | | /// <summary> |
+| | | 60 | | /// The CRC data checksum so far. |
+| | | 61 | | /// </summary> |
+| | | 62 | | uint checkValue; |
+| | | 63 | | #endregion |
+| | | 64 | | |
+| | | 65 | | /// <summary> |
+| | | 66 | | /// Initialise a default instance of <see cref="Adler32"></see> |
+| | | 67 | | /// </summary> |
+| | 709 | 68 | | public Adler32() |
+| | | 69 | | { |
+| | 709 | 70 | | Reset(); |
+| | 709 | 71 | | } |
+| | | 72 | | |
+| | | 73 | | /// <summary> |
+| | | 74 | | /// Resets the Adler32 data checksum as if no update was ever called. |
+| | | 75 | | /// </summary> |
+| | | 76 | | public void Reset() |
+| | | 77 | | { |
+| | 1143 | 78 | | checkValue = 1; |
+| | 1143 | 79 | | } |
+| | | 80 | | |
+| | | 81 | | /// <summary> |
+| | | 82 | | /// Returns the Adler32 data checksum computed so far. |
+| | | 83 | | /// </summary> |
+| | | 84 | | public long Value { |
+| | | 85 | | get { |
+| | 18 | 86 | | return checkValue; |
+| | | 87 | | } |
+| | | 88 | | } |
+| | | 89 | | |
+| | | 90 | | /// <summary> |
+| | | 91 | | /// Updates the checksum with the byte b. |
+| | | 92 | | /// </summary> |
+| | | 93 | | /// <param name="bval"> |
+| | | 94 | | /// The data value to add. The high byte of the int is ignored. |
+| | | 95 | | /// </param> |
+| | | 96 | | public void Update(int bval) |
+| | | 97 | | { |
+| | | 98 | | // We could make a length 1 byte array and call update again, but I |
+| | | 99 | | // would rather not have that overhead |
+| | 0 | 100 | | uint s1 = checkValue & 0xFFFF; |
+| | 0 | 101 | | uint s2 = checkValue >> 16; |
+| | | 102 | | |
+| | 0 | 103 | | s1 = (s1 + ((uint)bval & 0xFF)) % BASE; |
+| | 0 | 104 | | s2 = (s1 + s2) % BASE; |
+| | | 105 | | |
+| | 0 | 106 | | checkValue = (s2 << 16) + s1; |
+| | 0 | 107 | | } |
+| | | 108 | | |
+| | | 109 | | /// <summary> |
+| | | 110 | | /// Updates the Adler32 data checksum with the bytes taken from |
+| | | 111 | | /// a block of data. |
+| | | 112 | | /// </summary> |
+| | | 113 | | /// <param name="buffer">Contains the data to update the checksum with.</param> |
+| | | 114 | | public void Update(byte[] buffer) |
+| | | 115 | | { |
+| | 2 | 116 | | if (buffer == null) { |
+| | 1 | 117 | | throw new ArgumentNullException(nameof(buffer)); |
+| | | 118 | | } |
+| | | 119 | | |
+| | 1 | 120 | | Update(buffer, 0, buffer.Length); |
+| | 1 | 121 | | } |
+| | | 122 | | |
+| | | 123 | | /// <summary> |
+| | | 124 | | /// Update Adler32 data checksum based on a portion of a block of data |
+| | | 125 | | /// </summary> |
+| | | 126 | | /// <param name = "buffer">Contains the data to update the CRC with.</param> |
+| | | 127 | | /// <param name = "offset">The offset into the buffer where the data starts</param> |
+| | | 128 | | /// <param name = "count">The number of data bytes to update the CRC with.</param> |
+| | | 129 | | public void Update(byte[] buffer, int offset, int count) |
+| | | 130 | | { |
+| | 6204 | 131 | | if (buffer == null) { |
+| | 1 | 132 | | throw new ArgumentNullException(nameof(buffer)); |
+| | | 133 | | } |
| | | 134 | | |
-| | 0 | 135 | | s1 = (s1 + ((uint)value & 0xFF)) % BASE; |
-| | 0 | 136 | | s2 = (s1 + s2) % BASE; |
-| | | 137 | | |
-| | 0 | 138 | | checksum = (s2 << 16) + s1; |
-| | 0 | 139 | | } |
-| | | 140 | | |
-| | | 141 | | /// <summary> |
-| | | 142 | | /// Updates the checksum with an array of bytes. |
-| | | 143 | | /// </summary> |
-| | | 144 | | /// <param name="buffer"> |
-| | | 145 | | /// The source of the data to update with. |
-| | | 146 | | /// </param> |
-| | | 147 | | public void Update(byte[] buffer) |
-| | | 148 | | { |
-| | 0 | 149 | | if ( buffer == null ) { |
-| | 0 | 150 | | throw new ArgumentNullException(nameof(buffer)); |
-| | | 151 | | } |
-| | | 152 | | |
-| | 0 | 153 | | Update(buffer, 0, buffer.Length); |
-| | 0 | 154 | | } |
-| | | 155 | | |
-| | | 156 | | /// <summary> |
-| | | 157 | | /// Updates the checksum with the bytes taken from the array. |
-| | | 158 | | /// </summary> |
-| | | 159 | | /// <param name="buffer"> |
-| | | 160 | | /// an array of bytes |
-| | | 161 | | /// </param> |
-| | | 162 | | /// <param name="offset"> |
-| | | 163 | | /// the start of the data used for this update |
-| | | 164 | | /// </param> |
-| | | 165 | | /// <param name="count"> |
-| | | 166 | | /// the number of bytes to use for this update |
-| | | 167 | | /// </param> |
-| | | 168 | | public void Update(byte[] buffer, int offset, int count) |
-| | | 169 | | { |
-| | 6243 | 170 | | if (buffer == null) { |
-| | 0 | 171 | | throw new ArgumentNullException(nameof(buffer)); |
-| | | 172 | | } |
-| | | 173 | | |
-| | 6243 | 174 | | if (offset < 0) { |
-| | | 175 | | #if NETCF_1_0 |
-| | | 176 | | throw new ArgumentOutOfRangeException("offset"); |
-| | | 177 | | #else |
-| | 0 | 178 | | throw new ArgumentOutOfRangeException(nameof(offset), "cannot be negative"); |
-| | | 179 | | #endif |
-| | | 180 | | } |
-| | | 181 | | |
-| | 6243 | 182 | | if ( count < 0 ) |
-| | | 183 | | { |
-| | | 184 | | #if NETCF_1_0 |
-| | | 185 | | throw new ArgumentOutOfRangeException("count"); |
-| | | 186 | | #else |
-| | 0 | 187 | | throw new ArgumentOutOfRangeException(nameof(count), "cannot be negative"); |
-| | | 188 | | #endif |
-| | | 189 | | } |
-| | | 190 | | |
-| | 6243 | 191 | | if (offset >= buffer.Length) |
-| | | 192 | | { |
-| | | 193 | | #if NETCF_1_0 |
-| | | 194 | | throw new ArgumentOutOfRangeException("offset"); |
-| | | 195 | | #else |
-| | 0 | 196 | | throw new ArgumentOutOfRangeException(nameof(offset), "not a valid index into buffer"); |
-| | | 197 | | #endif |
-| | | 198 | | } |
-| | | 199 | | |
-| | 6243 | 200 | | if (offset + count > buffer.Length) |
-| | | 201 | | { |
-| | | 202 | | #if NETCF_1_0 |
-| | | 203 | | throw new ArgumentOutOfRangeException("count"); |
-| | | 204 | | #else |
-| | 0 | 205 | | throw new ArgumentOutOfRangeException(nameof(count), "exceeds buffer size"); |
-| | | 206 | | #endif |
-| | | 207 | | } |
-| | | 208 | | |
-| | | 209 | | //(By Per Bothner) |
-| | 6243 | 210 | | uint s1 = checksum & 0xFFFF; |
-| | 6243 | 211 | | uint s2 = checksum >> 16; |
-| | | 212 | | |
-| | 14027 | 213 | | while (count > 0) { |
-| | | 214 | | // We can defer the modulo operation: |
-| | | 215 | | // s1 maximally grows from 65521 to 65521 + 255 * 3800 |
-| | | 216 | | // s2 maximally grows by 3800 * median(s1) = 2090079800 < 2^31 |
-| | 7784 | 217 | | int n = 3800; |
-| | 7784 | 218 | | if (n > count) { |
-| | 6243 | 219 | | n = count; |
-| | | 220 | | } |
-| | 7784 | 221 | | count -= n; |
-| | 8556640 | 222 | | while (--n >= 0) { |
-| | 8548856 | 223 | | s1 = s1 + (uint)(buffer[offset++] & 0xff); |
-| | 8548856 | 224 | | s2 = s2 + s1; |
-| | | 225 | | } |
-| | 7784 | 226 | | s1 %= BASE; |
-| | 7784 | 227 | | s2 %= BASE; |
-| | | 228 | | } |
-| | | 229 | | |
-| | 6243 | 230 | | checksum = (s2 << 16) | s1; |
-| | 6243 | 231 | | } |
-| | | 232 | | |
-| | | 233 | | #region Instance Fields |
-| | | 234 | | uint checksum; |
-| | | 235 | | #endregion |
-| | | 236 | | } |
-| | | 237 | | } |
+| | 6203 | 135 | | if (offset < 0) { |
+| | 1 | 136 | | throw new ArgumentOutOfRangeException(nameof(offset), "cannot be less than zero"); |
+| | | 137 | | } |
+| | | 138 | | |
+| | 6202 | 139 | | if (offset >= buffer.Length) { |
+| | 1 | 140 | | throw new ArgumentOutOfRangeException(nameof(offset), "not a valid index into buffer"); |
+| | | 141 | | } |
+| | | 142 | | |
+| | 6201 | 143 | | if (count < 0) { |
+| | 1 | 144 | | throw new ArgumentOutOfRangeException(nameof(count), "cannot be less than zero"); |
+| | | 145 | | } |
+| | | 146 | | |
+| | 6200 | 147 | | if (offset + count > buffer.Length) { |
+| | 1 | 148 | | throw new ArgumentOutOfRangeException(nameof(count), "exceeds buffer size"); |
+| | | 149 | | } |
+| | | 150 | | |
+| | | 151 | | //(By Per Bothner) |
+| | 6199 | 152 | | uint s1 = checkValue & 0xFFFF; |
+| | 6199 | 153 | | uint s2 = checkValue >> 16; |
+| | | 154 | | |
+| | 13890 | 155 | | while (count > 0) { |
+| | | 156 | | // We can defer the modulo operation: |
+| | | 157 | | // s1 maximally grows from 65521 to 65521 + 255 * 3800 |
+| | | 158 | | // s2 maximally grows by 3800 * median(s1) = 2090079800 < 2^31 |
+| | 7691 | 159 | | int n = 3800; |
+| | 7691 | 160 | | if (n > count) { |
+| | 6199 | 161 | | n = count; |
+| | | 162 | | } |
+| | 7691 | 163 | | count -= n; |
+| | 8355525 | 164 | | while (--n >= 0) { |
+| | 8347834 | 165 | | s1 = s1 + (uint)(buffer[offset++] & 0xff); |
+| | 8347834 | 166 | | s2 = s2 + s1; |
+| | | 167 | | } |
+| | 7691 | 168 | | s1 %= BASE; |
+| | 7691 | 169 | | s2 %= BASE; |
+| | | 170 | | } |
+| | | 171 | | |
+| | 6199 | 172 | | checkValue = (s2 << 16) | s1; |
+| | 6199 | 173 | | } |
+| | | 174 | | } |
+| | | 175 | | } |