1 /*
2 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
38 * @author David Connelly
39 */
40 public
41 class CRC32 implements Checksum {
42 private int crc;
43
44 /**
45 * Creates a new CRC32 object.
46 */
47 public CRC32() {
48 }
49
50
51 /**
52 * Updates the CRC-32 checksum with the specified byte (the low
53 * eight bits of the argument b).
54 *
55 * @param b the byte to update the checksum with
56 */
57 public void update(int b) {
58 crc = update(crc, b);
59 }
60
61 /**
62 * Updates the CRC-32 checksum with the specified array of bytes.
63 */
64 public void update(byte[] b, int off, int len) {
65 if (b == null) {
66 throw new NullPointerException();
67 }
68 if (off < 0 || len < 0 || off > b.length - len) {
69 throw new ArrayIndexOutOfBoundsException();
70 }
71 crc = updateBytes(crc, b, off, len);
72 }
73
74 /**
75 * Updates the CRC-32 checksum with the specified array of bytes.
76 *
77 * @param b the array of bytes to update the checksum with
78 */
79 public void update(byte[] b) {
80 crc = updateBytes(crc, b, 0, b.length);
81 }
82
83 /**
84 * Updates the checksum with the bytes from the specified buffer.
85 *
86 * The checksum is updated using
87 * buffer.{@link java.nio.Buffer#remaining() remaining()}
88 * bytes starting at
89 * buffer.{@link java.nio.Buffer#position() position()}
90 * Upon return, the buffer's position will
91 * be updated to its limit; its limit will not have been changed.
92 *
114
115 /**
116 * Resets CRC-32 to initial value.
117 */
118 public void reset() {
119 crc = 0;
120 }
121
122 /**
123 * Returns CRC-32 value.
124 */
125 public long getValue() {
126 return (long)crc & 0xffffffffL;
127 }
128
129 private native static int update(int crc, int b);
130 private native static int updateBytes(int crc, byte[] b, int off, int len);
131
132 private native static int updateByteBuffer(int adler, long addr,
133 int off, int len);
134 }
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1 /*
2 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
38 * @author David Connelly
39 */
40 public
41 class CRC32 implements Checksum {
42 private int crc;
43
44 /**
45 * Creates a new CRC32 object.
46 */
47 public CRC32() {
48 }
49
50
51 /**
52 * Updates the CRC-32 checksum with the specified byte (the low
53 * eight bits of the argument b).
54 *
55 * @param b the byte to update the checksum with
56 */
57 public void update(int b) {
58 int c = ~ crc;
59 b = timesXtoThe32[(b ^ c) & 0xFF];
60 b = b ^ (c >>> 8);
61 crc = ~b;
62 }
63
64 /**
65 * Updates the CRC-32 checksum with the specified array of bytes.
66 */
67 public void update(byte[] b, int off, int len) {
68 if (b == null) {
69 throw new NullPointerException();
70 }
71 if (off < 0 || len < 0 || off > b.length - len) {
72 throw new ArrayIndexOutOfBoundsException();
73 }
74
75 if (len < javaCRCIfSmallerThan) {
76 crc = updateBytesSimple(crc, b, off, len);
77 } else {
78 crc = updateBytes(crc, b, off, len);
79 }
80 }
81
82 /**
83 * Updates the CRC-32 checksum with the specified array of bytes.
84 *
85 * @param b the array of bytes to update the checksum with
86 */
87 public void update(byte[] b) {
88 crc = updateBytes(crc, b, 0, b.length);
89 }
90
91 /**
92 * Updates the checksum with the bytes from the specified buffer.
93 *
94 * The checksum is updated using
95 * buffer.{@link java.nio.Buffer#remaining() remaining()}
96 * bytes starting at
97 * buffer.{@link java.nio.Buffer#position() position()}
98 * Upon return, the buffer's position will
99 * be updated to its limit; its limit will not have been changed.
100 *
122
123 /**
124 * Resets CRC-32 to initial value.
125 */
126 public void reset() {
127 crc = 0;
128 }
129
130 /**
131 * Returns CRC-32 value.
132 */
133 public long getValue() {
134 return (long)crc & 0xffffffffL;
135 }
136
137 private native static int update(int crc, int b);
138 private native static int updateBytes(int crc, byte[] b, int off, int len);
139
140 private native static int updateByteBuffer(int adler, long addr,
141 int off, int len);
142
143 /**
144 * Simple byte-at-a-time CRC for avoiding the overhead of native call.
145 * Breakeven ranges between 60 and 100 bytes.
146 */
147 private static int updateBytesSimple(int crc, byte[] b, int off, int len) {
148 int[] a = timesXtoThe32;
149 if (a.length < 256)
150 throw new ArrayIndexOutOfBoundsException();
151 int c = ~crc;
152 for (int i = 0; i < len; i++ ) {
153 int x0 = b[i + off];
154 x0 = a[(x0 ^ c) & 0xFF];
155 c = x0 ^ (c >>> 8);
156 }
157 return ~c;
158 }
159
160 /**
161 * Returns true if CLMUL is both requested and supported.
162 */
163 private native static boolean init(int[] timesXtoThe32, boolean try_use_clmul);
164
165 /**
166 * timesXtoThe32[a] = rep(poly(a)*x**32)
167 */
168 static int[] timesXtoThe32;
169
170 /**
171 * Estimated CRC size below which the JNI overhead is too large.
172 * May be modified depending on platform properties.
173 */
174 static int javaCRCIfSmallerThan = 80;
175
176 static {
177 timesXtoThe32 = new int[256];
178 boolean try_use_clmul =
179 "true".equals(sun.misc.VM.getSavedProperty("sun.zip.clmulSupported"));
180 init(timesXtoThe32, try_use_clmul);
181 }
182 }
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