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comparison app/src/main/java/com/jcraft/jzlib/Adler32.java @ 438:d29cce60f393

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migrate from Eclipse to Android Studio
author Carl Byington <carl@five-ten-sg.com>
date Thu, 03 Dec 2015 11:23:55 -0800
parents src/com/jcraft/jzlib/Adler32.java@46c2115ae1c8
children
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437:208b31032318 438:d29cce60f393
1 /* -*-mode:java; c-basic-offset:2; -*- */
2 /*
3 Copyright (c) 2000-2011 ymnk, JCraft,Inc. All rights reserved.
4
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions are met:
7
8 1. Redistributions of source code must retain the above copyright notice,
9 this list of conditions and the following disclaimer.
10
11 2. Redistributions in binary form must reproduce the above copyright
12 notice, this list of conditions and the following disclaimer in
13 the documentation and/or other materials provided with the distribution.
14
15 3. The names of the authors may not be used to endorse or promote products
16 derived from this software without specific prior written permission.
17
18 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
19 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
21 INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
22 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24 OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29 /*
30 * This program is based on zlib-1.1.3, so all credit should go authors
31 * Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
32 * and contributors of zlib.
33 */
34
35 package com.jcraft.jzlib;
36
37 final public class Adler32 implements Checksum {
38
39 // largest prime smaller than 65536
40 static final private int BASE=65521;
41 // NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
42 static final private int NMAX=5552;
43
44 private long s1=1L;
45 private long s2=0L;
46
47 public void reset(long init){
48 s1=init&0xffff;
49 s2=(init>>16)&0xffff;
50 }
51
52 public void reset(){
53 s1=1L;
54 s2=0L;
55 }
56
57 public long getValue(){
58 return ((s2<<16)|s1);
59 }
60
61 public void update(byte[] buf, int index, int len){
62
63 if(len==1){
64 s1+=buf[index++]&0xff; s2+=s1;
65 s1%=BASE;
66 s2%=BASE;
67 return;
68 }
69
70 int len1 = len/NMAX;
71 int len2 = len%NMAX;
72 while(len1-->0) {
73 int k=NMAX;
74 len-=k;
75 while(k-->0){
76 s1+=buf[index++]&0xff; s2+=s1;
77 }
78 s1%=BASE;
79 s2%=BASE;
80 }
81
82 int k=len2;
83 len-=k;
84 while(k-->0){
85 s1+=buf[index++]&0xff; s2+=s1;
86 }
87 s1%=BASE;
88 s2%=BASE;
89 }
90
91 public Adler32 copy(){
92 Adler32 foo = new Adler32();
93 foo.s1 = this.s1;
94 foo.s2 = this.s2;
95 return foo;
96 }
97
98 // The following logic has come from zlib.1.2.
99 static long combine(long adler1, long adler2, long len2){
100 long BASEL = (long)BASE;
101 long sum1;
102 long sum2;
103 long rem; // unsigned int
104
105 rem = len2 % BASEL;
106 sum1 = adler1 & 0xffffL;
107 sum2 = rem * sum1;
108 sum2 %= BASEL; // MOD(sum2);
109 sum1 += (adler2 & 0xffffL) + BASEL - 1;
110 sum2 += ((adler1 >> 16) & 0xffffL) + ((adler2 >> 16) & 0xffffL) + BASEL - rem;
111 if (sum1 >= BASEL) sum1 -= BASEL;
112 if (sum1 >= BASEL) sum1 -= BASEL;
113 if (sum2 >= (BASEL << 1)) sum2 -= (BASEL << 1);
114 if (sum2 >= BASEL) sum2 -= BASEL;
115 return sum1 | (sum2 << 16);
116 }
117
118 /*
119 private java.util.zip.Adler32 adler=new java.util.zip.Adler32();
120 public void update(byte[] buf, int index, int len){
121 if(buf==null) {adler.reset();}
122 else{adler.update(buf, index, len);}
123 }
124 public void reset(){
125 adler.reset();
126 }
127 public void reset(long init){
128 if(init==1L){
129 adler.reset();
130 }
131 else{
132 System.err.println("unsupported operation");
133 }
134 }
135 public long getValue(){
136 return adler.getValue();
137 }
138 */
139 }