mirror of https://github.com/NekoX-Dev/NekoX.git
361 lines
13 KiB
Java
Executable File
361 lines
13 KiB
Java
Executable File
/*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.zxing.qrcode.decoder;
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import com.google.zxing.DecodeHintType;
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import com.google.zxing.FormatException;
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import com.google.zxing.common.BitSource;
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import com.google.zxing.common.CharacterSetECI;
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import com.google.zxing.common.DecoderResult;
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import com.google.zxing.common.StringUtils;
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import java.io.UnsupportedEncodingException;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.List;
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import java.util.Map;
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/**
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* <p>QR Codes can encode text as bits in one of several modes, and can use multiple modes
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* in one QR Code. This class decodes the bits back into text.</p>
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*
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* <p>See ISO 18004:2006, 6.4.3 - 6.4.7</p>
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*
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* @author Sean Owen
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*/
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final class DecodedBitStreamParser {
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/**
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* See ISO 18004:2006, 6.4.4 Table 5
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*/
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private static final char[] ALPHANUMERIC_CHARS =
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"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:".toCharArray();
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private static final int GB2312_SUBSET = 1;
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private DecodedBitStreamParser() {
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}
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static DecoderResult decode(byte[] bytes,
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Version version,
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ErrorCorrectionLevel ecLevel,
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Map<DecodeHintType,?> hints) throws FormatException {
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BitSource bits = new BitSource(bytes);
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StringBuilder result = new StringBuilder(50);
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List<byte[]> byteSegments = new ArrayList<>(1);
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int symbolSequence = -1;
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int parityData = -1;
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try {
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CharacterSetECI currentCharacterSetECI = null;
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boolean fc1InEffect = false;
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Mode mode;
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do {
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// While still another segment to read...
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if (bits.available() < 4) {
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// OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
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mode = Mode.TERMINATOR;
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} else {
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mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
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}
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switch (mode) {
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case TERMINATOR:
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break;
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case FNC1_FIRST_POSITION:
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case FNC1_SECOND_POSITION:
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// We do little with FNC1 except alter the parsed result a bit according to the spec
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fc1InEffect = true;
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break;
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case STRUCTURED_APPEND:
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if (bits.available() < 16) {
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throw FormatException.getFormatInstance();
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}
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// sequence number and parity is added later to the result metadata
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// Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
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symbolSequence = bits.readBits(8);
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parityData = bits.readBits(8);
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break;
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case ECI:
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// Count doesn't apply to ECI
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int value = parseECIValue(bits);
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currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
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if (currentCharacterSetECI == null) {
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throw FormatException.getFormatInstance();
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}
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break;
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case HANZI:
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// First handle Hanzi mode which does not start with character count
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// Chinese mode contains a sub set indicator right after mode indicator
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int subset = bits.readBits(4);
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int countHanzi = bits.readBits(mode.getCharacterCountBits(version));
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if (subset == GB2312_SUBSET) {
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decodeHanziSegment(bits, result, countHanzi);
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}
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break;
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default:
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// "Normal" QR code modes:
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// How many characters will follow, encoded in this mode?
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int count = bits.readBits(mode.getCharacterCountBits(version));
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switch (mode) {
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case NUMERIC:
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decodeNumericSegment(bits, result, count);
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break;
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case ALPHANUMERIC:
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decodeAlphanumericSegment(bits, result, count, fc1InEffect);
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break;
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case BYTE:
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decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments, hints);
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break;
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case KANJI:
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decodeKanjiSegment(bits, result, count);
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break;
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default:
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throw FormatException.getFormatInstance();
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}
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break;
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}
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} while (mode != Mode.TERMINATOR);
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} catch (IllegalArgumentException iae) {
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// from readBits() calls
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throw FormatException.getFormatInstance();
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}
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return new DecoderResult(bytes,
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result.toString(),
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byteSegments.isEmpty() ? null : byteSegments,
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ecLevel == null ? null : ecLevel.toString(),
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symbolSequence,
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parityData);
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}
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/**
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* See specification GBT 18284-2000
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*/
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private static void decodeHanziSegment(BitSource bits,
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StringBuilder result,
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int count) throws FormatException {
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// Don't crash trying to read more bits than we have available.
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if (count * 13 > bits.available()) {
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throw FormatException.getFormatInstance();
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}
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// Each character will require 2 bytes. Read the characters as 2-byte pairs
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// and decode as GB2312 afterwards
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byte[] buffer = new byte[2 * count];
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int offset = 0;
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while (count > 0) {
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// Each 13 bits encodes a 2-byte character
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int twoBytes = bits.readBits(13);
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int assembledTwoBytes = ((twoBytes / 0x060) << 8) | (twoBytes % 0x060);
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if (assembledTwoBytes < 0x00A00) {
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// In the 0xA1A1 to 0xAAFE range
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assembledTwoBytes += 0x0A1A1;
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} else {
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// In the 0xB0A1 to 0xFAFE range
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assembledTwoBytes += 0x0A6A1;
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}
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buffer[offset] = (byte) ((assembledTwoBytes >> 8) & 0xFF);
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buffer[offset + 1] = (byte) (assembledTwoBytes & 0xFF);
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offset += 2;
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count--;
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}
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try {
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result.append(new String(buffer, StringUtils.GB2312));
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} catch (UnsupportedEncodingException ignored) {
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throw FormatException.getFormatInstance();
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}
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}
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private static void decodeKanjiSegment(BitSource bits,
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StringBuilder result,
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int count) throws FormatException {
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// Don't crash trying to read more bits than we have available.
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if (count * 13 > bits.available()) {
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throw FormatException.getFormatInstance();
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}
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// Each character will require 2 bytes. Read the characters as 2-byte pairs
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// and decode as Shift_JIS afterwards
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byte[] buffer = new byte[2 * count];
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int offset = 0;
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while (count > 0) {
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// Each 13 bits encodes a 2-byte character
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int twoBytes = bits.readBits(13);
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int assembledTwoBytes = ((twoBytes / 0x0C0) << 8) | (twoBytes % 0x0C0);
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if (assembledTwoBytes < 0x01F00) {
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// In the 0x8140 to 0x9FFC range
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assembledTwoBytes += 0x08140;
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} else {
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// In the 0xE040 to 0xEBBF range
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assembledTwoBytes += 0x0C140;
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}
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buffer[offset] = (byte) (assembledTwoBytes >> 8);
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buffer[offset + 1] = (byte) assembledTwoBytes;
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offset += 2;
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count--;
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}
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// Shift_JIS may not be supported in some environments:
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try {
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result.append(new String(buffer, StringUtils.SHIFT_JIS));
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} catch (UnsupportedEncodingException ignored) {
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throw FormatException.getFormatInstance();
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}
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}
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private static void decodeByteSegment(BitSource bits,
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StringBuilder result,
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int count,
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CharacterSetECI currentCharacterSetECI,
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Collection<byte[]> byteSegments,
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Map<DecodeHintType,?> hints) throws FormatException {
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// Don't crash trying to read more bits than we have available.
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if (8 * count > bits.available()) {
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throw FormatException.getFormatInstance();
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}
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byte[] readBytes = new byte[count];
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for (int i = 0; i < count; i++) {
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readBytes[i] = (byte) bits.readBits(8);
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}
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String encoding;
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if (currentCharacterSetECI == null) {
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// The spec isn't clear on this mode; see
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// section 6.4.5: t does not say which encoding to assuming
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// upon decoding. I have seen ISO-8859-1 used as well as
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// Shift_JIS -- without anything like an ECI designator to
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// give a hint.
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encoding = StringUtils.guessEncoding(readBytes, hints);
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} else {
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encoding = currentCharacterSetECI.name();
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}
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try {
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result.append(new String(readBytes, encoding));
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} catch (UnsupportedEncodingException ignored) {
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throw FormatException.getFormatInstance();
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}
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byteSegments.add(readBytes);
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}
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private static char toAlphaNumericChar(int value) throws FormatException {
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if (value >= ALPHANUMERIC_CHARS.length) {
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throw FormatException.getFormatInstance();
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}
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return ALPHANUMERIC_CHARS[value];
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}
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private static void decodeAlphanumericSegment(BitSource bits,
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StringBuilder result,
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int count,
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boolean fc1InEffect) throws FormatException {
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// Read two characters at a time
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int start = result.length();
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while (count > 1) {
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if (bits.available() < 11) {
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throw FormatException.getFormatInstance();
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}
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int nextTwoCharsBits = bits.readBits(11);
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result.append(toAlphaNumericChar(nextTwoCharsBits / 45));
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result.append(toAlphaNumericChar(nextTwoCharsBits % 45));
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count -= 2;
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}
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if (count == 1) {
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// special case: one character left
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if (bits.available() < 6) {
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throw FormatException.getFormatInstance();
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}
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result.append(toAlphaNumericChar(bits.readBits(6)));
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}
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// See section 6.4.8.1, 6.4.8.2
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if (fc1InEffect) {
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// We need to massage the result a bit if in an FNC1 mode:
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for (int i = start; i < result.length(); i++) {
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if (result.charAt(i) == '%') {
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if (i < result.length() - 1 && result.charAt(i + 1) == '%') {
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// %% is rendered as %
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result.deleteCharAt(i + 1);
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} else {
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// In alpha mode, % should be converted to FNC1 separator 0x1D
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result.setCharAt(i, (char) 0x1D);
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}
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}
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}
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}
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}
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private static void decodeNumericSegment(BitSource bits,
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StringBuilder result,
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int count) throws FormatException {
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// Read three digits at a time
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while (count >= 3) {
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// Each 10 bits encodes three digits
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if (bits.available() < 10) {
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throw FormatException.getFormatInstance();
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}
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int threeDigitsBits = bits.readBits(10);
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if (threeDigitsBits >= 1000) {
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throw FormatException.getFormatInstance();
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}
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result.append(toAlphaNumericChar(threeDigitsBits / 100));
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result.append(toAlphaNumericChar((threeDigitsBits / 10) % 10));
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result.append(toAlphaNumericChar(threeDigitsBits % 10));
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count -= 3;
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}
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if (count == 2) {
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// Two digits left over to read, encoded in 7 bits
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if (bits.available() < 7) {
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throw FormatException.getFormatInstance();
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}
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int twoDigitsBits = bits.readBits(7);
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if (twoDigitsBits >= 100) {
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throw FormatException.getFormatInstance();
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}
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result.append(toAlphaNumericChar(twoDigitsBits / 10));
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result.append(toAlphaNumericChar(twoDigitsBits % 10));
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} else if (count == 1) {
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// One digit left over to read
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if (bits.available() < 4) {
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throw FormatException.getFormatInstance();
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}
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int digitBits = bits.readBits(4);
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if (digitBits >= 10) {
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throw FormatException.getFormatInstance();
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}
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result.append(toAlphaNumericChar(digitBits));
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}
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}
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private static int parseECIValue(BitSource bits) throws FormatException {
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int firstByte = bits.readBits(8);
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if ((firstByte & 0x80) == 0) {
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// just one byte
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return firstByte & 0x7F;
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}
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if ((firstByte & 0xC0) == 0x80) {
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// two bytes
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int secondByte = bits.readBits(8);
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return ((firstByte & 0x3F) << 8) | secondByte;
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}
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if ((firstByte & 0xE0) == 0xC0) {
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// three bytes
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int secondThirdBytes = bits.readBits(16);
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return ((firstByte & 0x1F) << 16) | secondThirdBytes;
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}
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throw FormatException.getFormatInstance();
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}
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}
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