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1 | /* -*-mode:java; c-basic-offset:2; -*- */ |
2 | /* | |
3 | Copyright (c) 2000,2001,2002,2003 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 class Adler32{ | |
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 | long adler32(long adler, byte[] buf, int index, int len){ | |
45 | if(buf == null){ return 1L; } | |
46 | ||
47 | long s1=adler&0xffff; | |
48 | long s2=(adler>>16)&0xffff; | |
49 | int k; | |
50 | ||
51 | while(len > 0) { | |
52 | k=len<NMAX?len:NMAX; | |
53 | len-=k; | |
54 | while(k>=16){ | |
55 | s1+=buf[index++]&0xff; s2+=s1; | |
56 | s1+=buf[index++]&0xff; s2+=s1; | |
57 | s1+=buf[index++]&0xff; s2+=s1; | |
58 | s1+=buf[index++]&0xff; s2+=s1; | |
59 | s1+=buf[index++]&0xff; s2+=s1; | |
60 | s1+=buf[index++]&0xff; s2+=s1; | |
61 | s1+=buf[index++]&0xff; s2+=s1; | |
62 | s1+=buf[index++]&0xff; s2+=s1; | |
63 | s1+=buf[index++]&0xff; s2+=s1; | |
64 | s1+=buf[index++]&0xff; s2+=s1; | |
65 | s1+=buf[index++]&0xff; s2+=s1; | |
66 | s1+=buf[index++]&0xff; s2+=s1; | |
67 | s1+=buf[index++]&0xff; s2+=s1; | |
68 | s1+=buf[index++]&0xff; s2+=s1; | |
69 | s1+=buf[index++]&0xff; s2+=s1; | |
70 | s1+=buf[index++]&0xff; s2+=s1; | |
71 | k-=16; | |
72 | } | |
73 | if(k!=0){ | |
74 | do{ | |
75 | s1+=buf[index++]&0xff; s2+=s1; | |
76 | } | |
77 | while(--k!=0); | |
78 | } | |
79 | s1%=BASE; | |
80 | s2%=BASE; | |
81 | } | |
82 | return (s2<<16)|s1; | |
83 | } | |
84 | ||
85 | /* | |
86 | private java.util.zip.Adler32 adler=new java.util.zip.Adler32(); | |
87 | long adler32(long value, byte[] buf, int index, int len){ | |
88 | if(value==1) {adler.reset();} | |
89 | if(buf==null) {adler.reset();} | |
90 | else{adler.update(buf, index, len);} | |
91 | return adler.getValue(); | |
92 | } | |
93 | */ | |
94 | } |