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1   package net.sf.jpkgmk.util;
2   
3   import java.io.BufferedInputStream;
4   import java.io.File;
5   import java.io.FileInputStream;
6   import java.io.IOException;
7   import java.io.InputStream;
8   import java.util.zip.Checksum;
9   
10  
11  /**
12   * Implementation of the unix algorithm "cksum". For further information see 
13   * For details on the concrete algorithm that was used see 
14   * {@link http://www.opengroup.org/onlinepubs/009695399/utilities/cksum.html}
15   * 
16   * @author gommma (gommma AT users.sourceforge.net)
17   * @author Last changed by: $Author: gommma $
18   * @version $Revision: 2 $ $Date: 2008-08-20 21:14:19 +0200 (Mi, 20 Aug 2008) $
19   * @since 1.0
20   * @see http://users.cs.cf.ac.uk/htbin/systems/fedmanpage?1p+cksum
21   */
22  public class UnixChecksum implements Checksum
23  {
24  
25  	static int crctab[] = {
26  		0x00000000,
27  		0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
28  		0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6,
29  		0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
30  		0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac,
31  		0x5bd4b01b, 0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f,
32  		0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a,
33  		0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
34  		0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58,
35  		0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033,
36  		0xa4ad16ea, 0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe,
37  		0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
38  		0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4,
39  		0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
40  		0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5,
41  		0x2ac12072, 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
42  		0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07,
43  		0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c,
44  		0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1,
45  		0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
46  		0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b,
47  		0xbb60adfc, 0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698,
48  		0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d,
49  		0x94ea7b2a, 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
50  		0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f,
51  		0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
52  		0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80,
53  		0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
54  		0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a,
55  		0x58c1663d, 0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629,
56  		0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c,
57  		0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
58  		0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e,
59  		0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65,
60  		0xeba91bbc, 0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8,
61  		0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
62  		0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2,
63  		0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
64  		0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74,
65  		0x857130c3, 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
66  		0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21,
67  		0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a,
68  		0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087,
69  		0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
70  		0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d,
71  		0x2056cd3a, 0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce,
72  		0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb,
73  		0xdbee767c, 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
74  		0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09,
75  		0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
76  		0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf,
77  		0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
78  		};
79  
80  	private int value = 0;
81  	private int dataLength = 0;
82  //		unsigned long memcrc(const unsigned char *b, size_t n)
83  //		{
84  //		/*  Input arguments:
85  //		 *  const char*   b == byte sequence to checksum
86  //		 *  size_t        n == length of sequence
87  //		 */
88  //
89  //
90  //		    register unsigned   i, c, s = 0;
91  //
92  //
93  //		    for (i = n; i > 0; --i) {
94  //		        c = (unsigned)(*b++);
95  //		        s = (s << 8) ^ crctab[(s >> 24) ^ c];
96  //		    }
97  //
98  //
99  //		    /* Extend with the length of the string. */
100 //		    while (n != 0) {
101 //		        c = n & 0377;
102 //		        n >>= 8;
103 //		        s = (s << 8) ^ crctab[(s >> 24) ^ c];
104 //		    }
105 //
106 //
107 //		    return ˜s;
108 //		}
109 
110 	
111 	public static long createChecksum(File file) throws IOException
112 	{
113 		UnixChecksum unixChecksum = new UnixChecksum();
114 		InputStream input = new BufferedInputStream(new FileInputStream(file));
115 		try {
116 			int b=-1;
117 			while((b=input.read()) != -1) {
118 				unixChecksum.update(b);
119 			}
120 			return unixChecksum.getValue();
121 		}
122 		finally {
123 			StreamUtil.tryCloseStream(input);
124 		}
125 	}
126 	
127 	public static long createChecksum(byte[] data)
128 	{
129 		UnixChecksum unixChecksum = new UnixChecksum();
130 		unixChecksum.update(data);
131 		return unixChecksum.getValue();
132 	}
133 	
134 //	/**
135 //	 * Creates and returns the unix "cksum"
136 //	 * @param data
137 //	 * @return
138 //	 */
139 //	public long createChecksum(byte[] data)
140 //	{
141 //		int c = 0;
142 //		int sum = 0;
143 //		for(int i=0; i<data.length; i++) {
144 //			c = data[i];
145 //			sum = (sum << 8) ^ crctab[(sum >>> 24) ^ c];
146 //		}
147 //		
148 //		/* Extend with the length of the string. */
149 //		for(int size=data.length; size!=0; size >>>= 8) {
150 //			c = size & 0377;
151 //			sum = (sum << 8) ^ crctab[(sum >>> 24) ^ c];
152 //		}
153 //		
154 //		return ~sum & 0xFFFFFFFFL;
155 //	}
156 
157 	public long getValue() {
158 		/* Extend with the length of the string. */
159 		int c=0;
160 		int sum=this.value;
161 		for(int size=dataLength; size!=0; size >>>= 8) {
162 			c = size & 0377;
163 			sum = (sum << 8) ^ crctab[(sum >>> 24) ^ c];
164 		}
165 		return ~sum & 0xffffffffL;
166 	}
167 
168 	public void reset() {
169 		this.value = 0;
170 		this.dataLength = 0;
171 	}
172 
173 	public void update(int byt) {
174 		this.value = (this.value << 8) ^ crctab[(this.value >>> 24) ^ byt];
175 		// Increase the data length
176 		this.dataLength++;
177 	}
178 
179 	public void update(byte[] data) {
180 		update(data, 0, data.length);
181 //		int byt = 0;
182 //		for(int i=0; i<data.length; i++) {
183 //			byt = data[i];
184 //			update(byt);
185 //		}
186 	}
187 
188 	public void update(byte[] data, int off, int len) {
189 		if (data == null) {
190 		    throw new NullPointerException();
191 		}
192 		
193 	    if (off < 0 || len < 0 || off > data.length - len) {
194 		    throw new ArrayIndexOutOfBoundsException();
195 		}
196 
197 	    int endIdx = off+len;
198 	    int byt = 0;
199 	    for (int i = off; i < endIdx; i++) {
200 			byt = data[i];
201 			update(byt);
202 		}
203 	}
204 
205 	
206 //	public static void main(String[] args) throws Exception{
207 //		byte[] data = "bla fasel huhu".getBytes();
208 //		long res1 = new UnixChecksum().getCksum(data);
209 //		System.out.println(res1 + "  " + res2);
210 //		System.out.println(crctab.length);
211 //		System.out.println("CRtabs equal: " + Arrays.equals(crctab, crctab2));
212 //		System.out.println("" + Arrays.toString(crctab2));
213 //		
214 //		int i=1;
215 ////		int res = i^32 + i^26 + i^23 + i^22 + i^16 + i^12 + i^11 + i^10 + i^8 + i^7 + i^5 + i^4 + i^2 + i;// + 1; 
216 //		int res = i<<32 + i<<26 + i<<23 + i<<22 + i<<16 + i<<12 + i<<11 + i<<10 + i<<8 + i<<7 + i<<5 + i<<4 + i<<2 + i;// + 1; 
217 //		System.out.println(res);
218 //	}
219 }