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1 /**
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2 * Title: tn5250J
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3 * Copyright: Copyright (c) 2001
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4 * Company:
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5 * @author Kenneth J. Pouncey
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6 * @version 0.4
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7 *
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8 * Description:
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9 *
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10 * This program is free software; you can redistribute it and/or modify
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11 * it under the terms of the GNU General Public License as published by
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12 * the Free Software Foundation; either version 2, or (at your option)
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13 * any later version.
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14 *
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15 * This program is distributed in the hope that it will be useful,
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16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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18 * GNU General Public License for more details.
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19 *
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20 * You should have received a copy of the GNU General Public License
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21 * along with this software; see the file COPYING. If not, write to
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22 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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23 * Boston, MA 02111-1307 USA
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24 *
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25 */
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26 package org.tn5250j.framework.tn5250;
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27
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28 public class Stream5250 {
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29
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30 public int streamSize;
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31 public int opCode;
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32 public int dataStart;
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33 public int pos;
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34 public byte buffer[];
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35
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36 public Stream5250(byte abyte0[]) {
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37 buffer = abyte0;
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38 // size without end of record 0xFF 0xEF
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39 streamSize = (abyte0[0] & 0xff) << 8 | abyte0[1] & 0xff;
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40 opCode = abyte0[9];
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41 dataStart = 6 + abyte0[6];
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42 pos = dataStart;
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43 }
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44
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45 public Stream5250() {
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46 buffer = null;
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47 streamSize = 0;
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48 opCode = 0;
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49 dataStart = 0;
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50 pos = dataStart;
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51 }
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52
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53 /**
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54 * This method takes a byte array and initializes the object information
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55 * to be used.
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56 *
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57 * @param abyte0
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58 */
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59 public void initialize(byte abyte0[]) {
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60
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61 buffer = abyte0;
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62 // size without end of record 0xFF 0xEF
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63 streamSize = (abyte0[0] & 0xff) << 8 | abyte0[1] & 0xff;
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64 opCode = abyte0[9];
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65 dataStart = 6 + abyte0[6];
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66 pos = dataStart;
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67
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68 }
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69
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70 public final int getOpCode() {
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71 return opCode;
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72 }
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73
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74 public final byte getNextByte()
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75 throws Exception {
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76 if(buffer == null || pos > buffer.length)
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77 throw new Exception("Buffer length exceeded: " + pos);
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78 else
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79 return buffer[pos++];
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80 }
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81
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82 public final void setPrevByte()
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83 throws Exception {
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84 if(pos == 0) {
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85 throw new Exception("Index equals zero.");
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86 }
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87 else {
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88 pos--;
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89 return;
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90 }
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91 }
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92
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93 /**
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94 * Returns where we are in the buffer
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95 * @return position in the buffer
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96 */
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97 public final int getCurrentPos() {
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98 return pos;
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99 }
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100
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101 public final byte getByteOffset(int off)
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102 throws Exception {
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103
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104 if(buffer == null || (pos + off ) > buffer.length)
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105 throw new Exception("Buffer length exceeded: " + pos);
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106 else
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107 return buffer[pos + off];
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108
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109 }
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110
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111 public final boolean size() {
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112 return pos >= streamSize;
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113 }
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114
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115
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116 /**
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117 * Determines if any more bytes are available in the buffer to be processed.
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118 * @return yes or no
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119 */
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120 public final boolean hasNext() {
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121
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122 // return pos >= buffer.length;
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123 return pos < streamSize;
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124 }
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125
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126 /**
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127 * This routine will retrieve a segment based on the first two bytes being
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128 * the length of the segment.
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129 *
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130 * @return a new byte array containing the bytes of the segment.
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131 * @throws Exception
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132 */
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133 public final byte[] getSegment() throws Exception {
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134
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135 // The first two bytes contain the length of the segment.
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136 int length = ((buffer[pos] & 0xff )<< 8 | (buffer[pos+1] & 0xff));
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137 // allocate space for it.
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138 byte[] segment = new byte[length];
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139
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140 getSegment(segment,length,true);
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141
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142 return segment;
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143 }
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144
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145
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146 /**
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147 * This routine will retrieve a byte array based on the first two bytes being
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148 * the length of the segment.
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149 *
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150 * @param segment - byte array
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151 * @param length - length of segment to return
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152 * @param adjustPos - adjust the position of the buffer to the end of the seg
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153 * ment
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154 * @throws Exception
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155 */
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156 public final void getSegment(byte[] segment, int length, boolean adjustPos)
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157 throws Exception {
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158
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159 // If the length is larger than what is available throw an exception
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160 if((pos + length ) > buffer.length)
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161 throw new Exception("Buffer length exceeded: start " + pos
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162 + " length " + length);
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163 // use the system array copy to move the bytes from the buffer
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164 // to the allocated byte array
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165 System.arraycopy(buffer,pos,segment,0,length);
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166
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167 // update the offset to be after the segment so the next byte can be read
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168 if (adjustPos)
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169 pos +=length;
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170
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171 }
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172
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173 }
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