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annotate src/org/tmatesoft/hg/internal/DataAccess.java @ 122:e93101b97e4a

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Subtle defect: long & int constant gives wrong results for i2 > 32000+
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Fri, 04 Feb 2011 04:05:27 +0100
parents a3a2e5deb320
children d5268ca7715b
rev   line source
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1 /*
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2 * Copyright (c) 2010 TMate Software Ltd
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3 *
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4 * This program is free software; you can redistribute it and/or modify
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5 * it under the terms of the GNU General Public License as published by
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6 * the Free Software Foundation; version 2 of the License.
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7 *
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8 * This program is distributed in the hope that it will be useful,
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9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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11 * GNU General Public License for more details.
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12 *
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13 * For information on how to redistribute this software under
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14 * the terms of a license other than GNU General Public License
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15 * contact TMate Software at support@hg4j.com
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16 */
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17 package org.tmatesoft.hg.internal;
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19 import java.io.IOException;
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21 /**
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22 * relevant parts of DataInput, non-stream nature (seek operation), explicit check for end of data.
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23 * convenient skip (+/- bytes)
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24 * Primary goal - effective file read, so that clients don't need to care whether to call few
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25 * distinct getInt() or readBytes(totalForFewInts) and parse themselves instead in an attempt to optimize.
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26 *
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27 * @author Artem Tikhomirov
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28 * @author TMate Software Ltd.
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29 */
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30 public class DataAccess {
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31 public boolean isEmpty() {
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32 return true;
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33 }
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34 // absolute positioning
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35 public void seek(long offset) throws IOException {
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36 throw new UnsupportedOperationException();
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37 }
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38 // relative positioning
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39 public void skip(int bytes) throws IOException {
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40 throw new UnsupportedOperationException();
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41 }
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42 // shall be called once this object no longer needed
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43 public void done() {
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44 // no-op in this empty implementation
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45 }
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46 public int readInt() throws IOException {
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47 byte[] b = new byte[4];
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48 readBytes(b, 0, 4);
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49 return b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
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50 }
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51 public long readLong() throws IOException {
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52 byte[] b = new byte[8];
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53 readBytes(b, 0, 8);
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54 int i1 = b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
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55 int i2 = b[4] << 24 | (b[5] & 0xFF) << 16 | (b[6] & 0xFF) << 8 | (b[7] & 0xFF);
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56 return ((long) i1) << 32 | ((long) i2 & 0xFFFFFFFFl);
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57 }
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58 public void readBytes(byte[] buf, int offset, int length) throws IOException {
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59 throw new UnsupportedOperationException();
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60 }
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61 public byte readByte() throws IOException {
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62 throw new UnsupportedOperationException();
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63 }
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64 }