1 /* |
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2 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 package sun.net.httpclient.hpack; |
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26 |
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27 import java.nio.ByteBuffer; |
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28 import java.util.Arrays; |
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29 |
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30 final class IntegerWriter { |
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31 |
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32 private static final int NEW = 0; |
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33 private static final int CONFIGURED = 1; |
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34 private static final int FIRST_BYTE_WRITTEN = 2; |
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35 private static final int DONE = 4; |
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36 |
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37 private int state = NEW; |
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38 |
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39 private int payload; |
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40 private int N; |
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41 private int value; |
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42 |
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43 // |
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44 // 0 1 2 3 4 5 6 7 |
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45 // +---+---+---+---+---+---+---+---+ |
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46 // | | | | | | | | | |
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47 // +---+---+---+-------------------+ |
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48 // |<--------->|<----------------->| |
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49 // payload N=5 |
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50 // |
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51 // payload is the contents of the left-hand side part of the octet; |
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52 // it is truncated to fit into 8-N bits, where 1 <= N <= 8; |
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53 // |
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54 public IntegerWriter configure(int value, int N, int payload) { |
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55 if (state != NEW) { |
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56 throw new IllegalStateException("Already configured"); |
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57 } |
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58 if (value < 0) { |
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59 throw new IllegalArgumentException("value >= 0: value=" + value); |
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60 } |
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61 checkPrefix(N); |
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62 this.value = value; |
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63 this.N = N; |
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64 this.payload = payload & 0xFF & (0xFFFFFFFF << N); |
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65 state = CONFIGURED; |
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66 return this; |
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67 } |
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68 |
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69 public boolean write(ByteBuffer output) { |
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70 if (state == NEW) { |
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71 throw new IllegalStateException("Configure first"); |
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72 } |
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73 if (state == DONE) { |
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74 return true; |
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75 } |
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76 |
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77 if (!output.hasRemaining()) { |
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78 return false; |
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79 } |
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80 if (state == CONFIGURED) { |
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81 int max = (2 << (N - 1)) - 1; |
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82 if (value < max) { |
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83 output.put((byte) (payload | value)); |
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84 state = DONE; |
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85 return true; |
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86 } |
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87 output.put((byte) (payload | max)); |
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88 value -= max; |
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89 state = FIRST_BYTE_WRITTEN; |
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90 } |
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91 if (state == FIRST_BYTE_WRITTEN) { |
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92 while (value >= 128 && output.hasRemaining()) { |
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93 output.put((byte) (value % 128 + 128)); |
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94 value /= 128; |
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95 } |
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96 if (!output.hasRemaining()) { |
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97 return false; |
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98 } |
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99 output.put((byte) value); |
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100 state = DONE; |
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101 return true; |
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102 } |
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103 throw new InternalError(Arrays.toString( |
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104 new Object[]{state, payload, N, value})); |
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105 } |
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106 |
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107 private static void checkPrefix(int N) { |
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108 if (N < 1 || N > 8) { |
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109 throw new IllegalArgumentException("1 <= N <= 8: N= " + N); |
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110 } |
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111 } |
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112 |
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113 public IntegerWriter reset() { |
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114 state = NEW; |
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115 return this; |
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116 } |
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117 } |
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