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18 package org.apache.commons.codec.binary;
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20 import java.util.Objects;
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22 import org.apache.commons.codec.CodecPolicy;
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42 public class Base16 extends BaseNCodec {
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47 private static final int BITS_PER_ENCODED_BYTE = 4;
48 private static final int BYTES_PER_ENCODED_BLOCK = 2;
49 private static final int BYTES_PER_UNENCODED_BLOCK = 1;
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56 private static final byte[] UPPER_CASE_DECODE_TABLE = {
57
58 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
59 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
60 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
61 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
62 -1, 10, 11, 12, 13, 14, 15
63 };
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70 private static final byte[] UPPER_CASE_ENCODE_TABLE = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
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77 private static final byte[] LOWER_CASE_DECODE_TABLE = {
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79 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
80 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
81 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
82 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
83 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
84 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
85 -1, 10, 11, 12, 13, 14, 15
86 };
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92 private static final byte[] LOWER_CASE_ENCODE_TABLE = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
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95 private static final int MASK_4_BITS = 0x0f;
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100 private final byte[] decodeTable;
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105 private final byte[] encodeTable;
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110 public Base16() {
111 this(false);
112 }
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119 public Base16(final boolean lowerCase) {
120 this(lowerCase, DECODING_POLICY_DEFAULT);
121 }
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128 private Base16(final byte[] encodeTable, final CodecPolicy decodingPolicy) {
129 super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK, 0, 0, PAD_DEFAULT, decodingPolicy);
130 Objects.requireNonNull(encodeTable, "encodeTable");
131 this.encodeTable = encodeTable;
132 this.decodeTable = encodeTable == LOWER_CASE_ENCODE_TABLE ? LOWER_CASE_DECODE_TABLE : UPPER_CASE_DECODE_TABLE;
133 }
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141 public Base16(final boolean lowerCase, final CodecPolicy decodingPolicy) {
142 this(lowerCase ? LOWER_CASE_ENCODE_TABLE : UPPER_CASE_ENCODE_TABLE, decodingPolicy);
143 }
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145 @Override
146 void decode(final byte[] data, int offset, final int length, final Context context) {
147 if (context.eof || length < 0) {
148 context.eof = true;
149 if (context.ibitWorkArea != 0) {
150 validateTrailingCharacter();
151 }
152 return;
153 }
154 final int dataLen = Math.min(data.length - offset, length);
155 final int availableChars = (context.ibitWorkArea != 0 ? 1 : 0) + dataLen;
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157 if (availableChars == 1 && availableChars == dataLen) {
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159 context.ibitWorkArea = decodeOctet(data[offset]) + 1;
160 return;
161 }
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163 final int charsToProcess = availableChars % BYTES_PER_ENCODED_BLOCK == 0 ? availableChars : availableChars - 1;
164 final int end = offset + dataLen;
165 final byte[] buffer = ensureBufferSize(charsToProcess / BYTES_PER_ENCODED_BLOCK, context);
166 int result;
167 if (dataLen < availableChars) {
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169 result = context.ibitWorkArea - 1 << BITS_PER_ENCODED_BYTE;
170 result |= decodeOctet(data[offset++]);
171 buffer[context.pos++] = (byte) result;
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173 context.ibitWorkArea = 0;
174 }
175 final int loopEnd = end - 1;
176 while (offset < loopEnd) {
177 result = decodeOctet(data[offset++]) << BITS_PER_ENCODED_BYTE;
178 result |= decodeOctet(data[offset++]);
179 buffer[context.pos++] = (byte) result;
180 }
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182 if (offset < end) {
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184 context.ibitWorkArea = decodeOctet(data[offset]) + 1;
185 }
186 }
187
188 private int decodeOctet(final byte octet) {
189 int decoded = -1;
190 if ((octet & 0xff) < decodeTable.length) {
191 decoded = decodeTable[octet];
192 }
193 if (decoded == -1) {
194 throw new IllegalArgumentException("Invalid octet in encoded value: " + (int) octet);
195 }
196 return decoded;
197 }
198
199 @Override
200 void encode(final byte[] data, final int offset, final int length, final Context context) {
201 if (context.eof) {
202 return;
203 }
204 if (length < 0) {
205 context.eof = true;
206 return;
207 }
208 final int size = length * BYTES_PER_ENCODED_BLOCK;
209 if (size < 0) {
210 throw new IllegalArgumentException("Input length exceeds maximum size for encoded data: " + length);
211 }
212 final byte[] buffer = ensureBufferSize(size, context);
213 final int end = offset + length;
214 for (int i = offset; i < end; i++) {
215 final int value = data[i];
216 final int high = value >> BITS_PER_ENCODED_BYTE & MASK_4_BITS;
217 final int low = value & MASK_4_BITS;
218 buffer[context.pos++] = encodeTable[high];
219 buffer[context.pos++] = encodeTable[low];
220 }
221 }
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229 @Override
230 public boolean isInAlphabet(final byte octet) {
231 return (octet & 0xff) < decodeTable.length && decodeTable[octet] != -1;
232 }
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239 private void validateTrailingCharacter() {
240 if (isStrictDecoding()) {
241 throw new IllegalArgumentException("Strict decoding: Last encoded character is a valid base 16 alphabet character but not a possible encoding. " +
242 "Decoding requires at least two characters to create one byte.");
243 }
244 }
245 }