Add parts of zxing library to generate qr codes

1 files changed, 557 insertions, 0 deletions

diff --git a/OpenPGP-Keychain/src/com/google/zxing/qrcode/encoder/Encoder.java b/OpenPGP-Keychain/src/com/google/zxing/qrcode/encoder/Encoder.java
new file mode 100644
index 000000000..8796511ab
--- /dev/null
+++ b/OpenPGP-Keychain/src/com/google/zxing/qrcode/encoder/Encoder.java
@@ -0,0 +1,557 @@
+/*
+ * Copyright 2008 ZXing authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.zxing.qrcode.encoder;
+
+import com.google.zxing.EncodeHintType;
+import com.google.zxing.WriterException;
+import com.google.zxing.common.BitArray;
+import com.google.zxing.common.CharacterSetECI;
+import com.google.zxing.common.ECI;
+import com.google.zxing.common.reedsolomon.GenericGF;
+import com.google.zxing.common.reedsolomon.ReedSolomonEncoder;
+import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
+import com.google.zxing.qrcode.decoder.Mode;
+import com.google.zxing.qrcode.decoder.Version;
+
+import java.io.UnsupportedEncodingException;
+import java.util.Hashtable;
+import java.util.Vector;
+
+/**
+ * @author satorux@google.com (Satoru Takabayashi) - creator
+ * @author dswitkin@google.com (Daniel Switkin) - ported from C++
+ */
+public final class Encoder {
+
+  // The original table is defined in the table 5 of JISX0510:2004 (p.19).
+  private static final int[] ALPHANUMERIC_TABLE = {
+      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 0x00-0x0f
+      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 0x10-0x1f
+      36, -1, -1, -1, 37, 38, -1, -1, -1, -1, 39, 40, -1, 41, 42, 43,  // 0x20-0x2f
+      0,   1,  2,  3,  4,  5,  6,  7,  8,  9, 44, -1, -1, -1, -1, -1,  // 0x30-0x3f
+      -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,  // 0x40-0x4f
+      25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1,  // 0x50-0x5f
+  };
+
+  static final String DEFAULT_BYTE_MODE_ENCODING = "ISO-8859-1";
+
+  private Encoder() {
+  }
+
+  // The mask penalty calculation is complicated.  See Table 21 of JISX0510:2004 (p.45) for details.
+  // Basically it applies four rules and summate all penalties.
+  private static int calculateMaskPenalty(ByteMatrix matrix) {
+    int penalty = 0;
+    penalty += MaskUtil.applyMaskPenaltyRule1(matrix);
+    penalty += MaskUtil.applyMaskPenaltyRule2(matrix);
+    penalty += MaskUtil.applyMaskPenaltyRule3(matrix);
+    penalty += MaskUtil.applyMaskPenaltyRule4(matrix);
+    return penalty;
+  }
+
+  /**
+   *  Encode "bytes" with the error correction level "ecLevel". The encoding mode will be chosen
+   * internally by chooseMode(). On success, store the result in "qrCode".
+   *
+   * We recommend you to use QRCode.EC_LEVEL_L (the lowest level) for
+   * "getECLevel" since our primary use is to show QR code on desktop screens. We don't need very
+   * strong error correction for this purpose.
+   *
+   * Note that there is no way to encode bytes in MODE_KANJI. We might want to add EncodeWithMode()
+   * with which clients can specify the encoding mode. For now, we don't need the functionality.
+   */
+  public static void encode(String content, ErrorCorrectionLevel ecLevel, QRCode qrCode)
+      throws WriterException {
+    encode(content, ecLevel, null, qrCode);
+  }
+
+  public static void encode(String content, ErrorCorrectionLevel ecLevel, Hashtable hints,
+      QRCode qrCode) throws WriterException {
+
+    String encoding = hints == null ? null : (String) hints.get(EncodeHintType.CHARACTER_SET);
+    if (encoding == null) {
+      encoding = DEFAULT_BYTE_MODE_ENCODING;
+    }
+
+    // Step 1: Choose the mode (encoding).
+    Mode mode = chooseMode(content, encoding);
+
+    // Step 2: Append "bytes" into "dataBits" in appropriate encoding.
+    BitArray dataBits = new BitArray();
+    appendBytes(content, mode, dataBits, encoding);
+    // Step 3: Initialize QR code that can contain "dataBits".
+    int numInputBytes = dataBits.getSizeInBytes();
+    initQRCode(numInputBytes, ecLevel, mode, qrCode);
+
+    // Step 4: Build another bit vector that contains header and data.
+    BitArray headerAndDataBits = new BitArray();
+
+    // Step 4.5: Append ECI message if applicable
+    if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.equals(encoding)) {
+      CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encoding);
+      if (eci != null) {
+        appendECI(eci, headerAndDataBits);
+      }
+    }
+
+    appendModeInfo(mode, headerAndDataBits);
+
+    int numLetters = mode.equals(Mode.BYTE) ? dataBits.getSizeInBytes() : content.length();
+    appendLengthInfo(numLetters, qrCode.getVersion(), mode, headerAndDataBits);
+    headerAndDataBits.appendBitArray(dataBits);
+
+    // Step 5: Terminate the bits properly.
+    terminateBits(qrCode.getNumDataBytes(), headerAndDataBits);
+
+    // Step 6: Interleave data bits with error correction code.
+    BitArray finalBits = new BitArray();
+    interleaveWithECBytes(headerAndDataBits, qrCode.getNumTotalBytes(), qrCode.getNumDataBytes(),
+        qrCode.getNumRSBlocks(), finalBits);
+
+    // Step 7: Choose the mask pattern and set to "qrCode".
+    ByteMatrix matrix = new ByteMatrix(qrCode.getMatrixWidth(), qrCode.getMatrixWidth());
+    qrCode.setMaskPattern(chooseMaskPattern(finalBits, qrCode.getECLevel(), qrCode.getVersion(),
+        matrix));
+
+    // Step 8.  Build the matrix and set it to "qrCode".
+    MatrixUtil.buildMatrix(finalBits, qrCode.getECLevel(), qrCode.getVersion(),
+        qrCode.getMaskPattern(), matrix);
+    qrCode.setMatrix(matrix);
+    // Step 9.  Make sure we have a valid QR Code.
+    if (!qrCode.isValid()) {
+      throw new WriterException("Invalid QR code: " + qrCode.toString());
+    }
+  }
+
+  /**
+   * @return the code point of the table used in alphanumeric mode or
+   *  -1 if there is no corresponding code in the table.
+   */
+  static int getAlphanumericCode(int code) {
+    if (code < ALPHANUMERIC_TABLE.length) {
+      return ALPHANUMERIC_TABLE[code];
+    }
+    return -1;
+  }
+
+  public static Mode chooseMode(String content) {
+    return chooseMode(content, null);
+  }
+
+  /**
+   * Choose the best mode by examining the content. Note that 'encoding' is used as a hint;
+   * if it is Shift_JIS, and the input is only double-byte Kanji, then we return {@link Mode#KANJI}.
+   */
+  public static Mode chooseMode(String content, String encoding) {
+    if ("Shift_JIS".equals(encoding)) {
+      // Choose Kanji mode if all input are double-byte characters
+      return isOnlyDoubleByteKanji(content) ? Mode.KANJI : Mode.BYTE;
+    }
+    boolean hasNumeric = false;
+    boolean hasAlphanumeric = false;
+    for (int i = 0; i < content.length(); ++i) {
+      char c = content.charAt(i);
+      if (c >= '0' && c <= '9') {
+        hasNumeric = true;
+      } else if (getAlphanumericCode(c) != -1) {
+        hasAlphanumeric = true;
+      } else {
+        return Mode.BYTE;
+      }
+    }
+    if (hasAlphanumeric) {
+      return Mode.ALPHANUMERIC;
+    } else if (hasNumeric) {
+      return Mode.NUMERIC;
+    }
+    return Mode.BYTE;
+  }
+
+  private static boolean isOnlyDoubleByteKanji(String content) {
+    byte[] bytes;
+    try {
+      bytes = content.getBytes("Shift_JIS");
+    } catch (UnsupportedEncodingException uee) {
+      return false;
+    }
+    int length = bytes.length;
+    if (length % 2 != 0) {
+      return false;
+    }
+    for (int i = 0; i < length; i += 2) {
+      int byte1 = bytes[i] & 0xFF;
+      if ((byte1 < 0x81 || byte1 > 0x9F) && (byte1 < 0xE0 || byte1 > 0xEB)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  private static int chooseMaskPattern(BitArray bits, ErrorCorrectionLevel ecLevel, int version,
+      ByteMatrix matrix) throws WriterException {
+
+    int minPenalty = Integer.MAX_VALUE;  // Lower penalty is better.
+    int bestMaskPattern = -1;
+    // We try all mask patterns to choose the best one.
+    for (int maskPattern = 0; maskPattern < QRCode.NUM_MASK_PATTERNS; maskPattern++) {
+      MatrixUtil.buildMatrix(bits, ecLevel, version, maskPattern, matrix);
+      int penalty = calculateMaskPenalty(matrix);
+      if (penalty < minPenalty) {
+        minPenalty = penalty;
+        bestMaskPattern = maskPattern;
+      }
+    }
+    return bestMaskPattern;
+  }
+
+  /**
+   * Initialize "qrCode" according to "numInputBytes", "ecLevel", and "mode". On success,
+   * modify "qrCode".
+   */
+  private static void initQRCode(int numInputBytes, ErrorCorrectionLevel ecLevel, Mode mode,
+      QRCode qrCode) throws WriterException {
+    qrCode.setECLevel(ecLevel);
+    qrCode.setMode(mode);
+
+    // In the following comments, we use numbers of Version 7-H.
+    for (int versionNum = 1; versionNum <= 40; versionNum++) {
+      Version version = Version.getVersionForNumber(versionNum);
+      // numBytes = 196
+      int numBytes = version.getTotalCodewords();
+      // getNumECBytes = 130
+      Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);
+      int numEcBytes = ecBlocks.getTotalECCodewords();
+      // getNumRSBlocks = 5
+      int numRSBlocks = ecBlocks.getNumBlocks();
+      // getNumDataBytes = 196 - 130 = 66
+      int numDataBytes = numBytes - numEcBytes;
+      // We want to choose the smallest version which can contain data of "numInputBytes" + some
+      // extra bits for the header (mode info and length info). The header can be three bytes
+      // (precisely 4 + 16 bits) at most. Hence we do +3 here.
+      if (numDataBytes >= numInputBytes + 3) {
+        // Yay, we found the proper rs block info!
+        qrCode.setVersion(versionNum);
+        qrCode.setNumTotalBytes(numBytes);
+        qrCode.setNumDataBytes(numDataBytes);
+        qrCode.setNumRSBlocks(numRSBlocks);
+        // getNumECBytes = 196 - 66 = 130
+        qrCode.setNumECBytes(numEcBytes);
+        // matrix width = 21 + 6 * 4 = 45
+        qrCode.setMatrixWidth(version.getDimensionForVersion());
+        return;
+      }
+    }
+    throw new WriterException("Cannot find proper rs block info (input data too big?)");
+  }
+
+  /**
+   * Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).
+   */
+  static void terminateBits(int numDataBytes, BitArray bits) throws WriterException {
+    int capacity = numDataBytes << 3;
+    if (bits.getSize() > capacity) {
+      throw new WriterException("data bits cannot fit in the QR Code" + bits.getSize() + " > " +
+          capacity);
+    }
+    for (int i = 0; i < 4 && bits.getSize() < capacity; ++i) {
+      bits.appendBit(false);
+    }
+    // Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details.
+    // If the last byte isn't 8-bit aligned, we'll add padding bits.
+    int numBitsInLastByte = bits.getSize() & 0x07;    
+    if (numBitsInLastByte > 0) {
+      for (int i = numBitsInLastByte; i < 8; i++) {
+        bits.appendBit(false);
+      }
+    }
+    // If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24).
+    int numPaddingBytes = numDataBytes - bits.getSizeInBytes();
+    for (int i = 0; i < numPaddingBytes; ++i) {
+      bits.appendBits((i & 0x01) == 0 ? 0xEC : 0x11, 8);
+    }
+    if (bits.getSize() != capacity) {
+      throw new WriterException("Bits size does not equal capacity");
+    }
+  }
+
+  /**
+   * Get number of data bytes and number of error correction bytes for block id "blockID". Store
+   * the result in "numDataBytesInBlock", and "numECBytesInBlock". See table 12 in 8.5.1 of
+   * JISX0510:2004 (p.30)
+   */
+  static void getNumDataBytesAndNumECBytesForBlockID(int numTotalBytes, int numDataBytes,
+      int numRSBlocks, int blockID, int[] numDataBytesInBlock,
+      int[] numECBytesInBlock) throws WriterException {
+    if (blockID >= numRSBlocks) {
+      throw new WriterException("Block ID too large");
+    }
+    // numRsBlocksInGroup2 = 196 % 5 = 1
+    int numRsBlocksInGroup2 = numTotalBytes % numRSBlocks;
+    // numRsBlocksInGroup1 = 5 - 1 = 4
+    int numRsBlocksInGroup1 = numRSBlocks - numRsBlocksInGroup2;
+    // numTotalBytesInGroup1 = 196 / 5 = 39
+    int numTotalBytesInGroup1 = numTotalBytes / numRSBlocks;
+    // numTotalBytesInGroup2 = 39 + 1 = 40
+    int numTotalBytesInGroup2 = numTotalBytesInGroup1 + 1;
+    // numDataBytesInGroup1 = 66 / 5 = 13
+    int numDataBytesInGroup1 = numDataBytes / numRSBlocks;
+    // numDataBytesInGroup2 = 13 + 1 = 14
+    int numDataBytesInGroup2 = numDataBytesInGroup1 + 1;
+    // numEcBytesInGroup1 = 39 - 13 = 26
+    int numEcBytesInGroup1 = numTotalBytesInGroup1 - numDataBytesInGroup1;
+    // numEcBytesInGroup2 = 40 - 14 = 26
+    int numEcBytesInGroup2 = numTotalBytesInGroup2 - numDataBytesInGroup2;
+    // Sanity checks.
+    // 26 = 26
+    if (numEcBytesInGroup1 != numEcBytesInGroup2) {
+      throw new WriterException("EC bytes mismatch");
+    }
+    // 5 = 4 + 1.
+    if (numRSBlocks != numRsBlocksInGroup1 + numRsBlocksInGroup2) {
+      throw new WriterException("RS blocks mismatch");
+    }
+    // 196 = (13 + 26) * 4 + (14 + 26) * 1
+    if (numTotalBytes !=
+        ((numDataBytesInGroup1 + numEcBytesInGroup1) *
+            numRsBlocksInGroup1) +
+            ((numDataBytesInGroup2 + numEcBytesInGroup2) *
+                numRsBlocksInGroup2)) {
+      throw new WriterException("Total bytes mismatch");
+    }
+
+    if (blockID < numRsBlocksInGroup1) {
+      numDataBytesInBlock[0] = numDataBytesInGroup1;
+      numECBytesInBlock[0] = numEcBytesInGroup1;
+    } else {
+      numDataBytesInBlock[0] = numDataBytesInGroup2;
+      numECBytesInBlock[0] = numEcBytesInGroup2;
+    }
+  }
+
+  /**
+   * Interleave "bits" with corresponding error correction bytes. On success, store the result in
+   * "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details.
+   */
+  static void interleaveWithECBytes(BitArray bits, int numTotalBytes,
+      int numDataBytes, int numRSBlocks, BitArray result) throws WriterException {
+
+    // "bits" must have "getNumDataBytes" bytes of data.
+    if (bits.getSizeInBytes() != numDataBytes) {
+      throw new WriterException("Number of bits and data bytes does not match");
+    }
+
+    // Step 1.  Divide data bytes into blocks and generate error correction bytes for them. We'll
+    // store the divided data bytes blocks and error correction bytes blocks into "blocks".
+    int dataBytesOffset = 0;
+    int maxNumDataBytes = 0;
+    int maxNumEcBytes = 0;
+
+    // Since, we know the number of reedsolmon blocks, we can initialize the vector with the number.
+    Vector blocks = new Vector(numRSBlocks);
+
+    for (int i = 0; i < numRSBlocks; ++i) {
+      int[] numDataBytesInBlock = new int[1];
+      int[] numEcBytesInBlock = new int[1];
+      getNumDataBytesAndNumECBytesForBlockID(
+          numTotalBytes, numDataBytes, numRSBlocks, i,
+          numDataBytesInBlock, numEcBytesInBlock);
+
+      int size = numDataBytesInBlock[0];
+      byte[] dataBytes = new byte[size];
+      bits.toBytes(8*dataBytesOffset, dataBytes, 0, size);
+      byte[] ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]);
+      blocks.addElement(new BlockPair(dataBytes, ecBytes));
+
+      maxNumDataBytes = Math.max(maxNumDataBytes, size);
+      maxNumEcBytes = Math.max(maxNumEcBytes, ecBytes.length);
+      dataBytesOffset += numDataBytesInBlock[0];
+    }
+    if (numDataBytes != dataBytesOffset) {
+      throw new WriterException("Data bytes does not match offset");
+    }
+
+    // First, place data blocks.
+    for (int i = 0; i < maxNumDataBytes; ++i) {
+      for (int j = 0; j < blocks.size(); ++j) {
+        byte[] dataBytes = ((BlockPair) blocks.elementAt(j)).getDataBytes();
+        if (i < dataBytes.length) {
+          result.appendBits(dataBytes[i], 8);
+        }
+      }
+    }
+    // Then, place error correction blocks.
+    for (int i = 0; i < maxNumEcBytes; ++i) {
+      for (int j = 0; j < blocks.size(); ++j) {
+        byte[] ecBytes = ((BlockPair) blocks.elementAt(j)).getErrorCorrectionBytes();
+        if (i < ecBytes.length) {
+          result.appendBits(ecBytes[i], 8);
+        }
+      }
+    }
+    if (numTotalBytes != result.getSizeInBytes()) {  // Should be same.
+      throw new WriterException("Interleaving error: " + numTotalBytes + " and " +
+          result.getSizeInBytes() + " differ.");
+    }
+  }
+
+  static byte[] generateECBytes(byte[] dataBytes, int numEcBytesInBlock) {
+    int numDataBytes = dataBytes.length;
+    int[] toEncode = new int[numDataBytes + numEcBytesInBlock];
+    for (int i = 0; i < numDataBytes; i++) {
+      toEncode[i] = dataBytes[i] & 0xFF;
+    }
+    new ReedSolomonEncoder(GenericGF.QR_CODE_FIELD_256).encode(toEncode, numEcBytesInBlock);
+
+    byte[] ecBytes = new byte[numEcBytesInBlock];
+    for (int i = 0; i < numEcBytesInBlock; i++) {
+      ecBytes[i] = (byte) toEncode[numDataBytes + i];
+    }
+    return ecBytes;
+  }
+
+  /**
+   * Append mode info. On success, store the result in "bits".
+   */
+  static void appendModeInfo(Mode mode, BitArray bits) {
+    bits.appendBits(mode.getBits(), 4);
+  }
+
+
+  /**
+   * Append length info. On success, store the result in "bits".
+   */
+  static void appendLengthInfo(int numLetters, int version, Mode mode, BitArray bits)
+      throws WriterException {
+    int numBits = mode.getCharacterCountBits(Version.getVersionForNumber(version));
+    if (numLetters > ((1 << numBits) - 1)) {
+      throw new WriterException(numLetters + "is bigger than" + ((1 << numBits) - 1));
+    }
+    bits.appendBits(numLetters, numBits);
+  }
+
+  /**
+   * Append "bytes" in "mode" mode (encoding) into "bits". On success, store the result in "bits".
+   */
+  static void appendBytes(String content, Mode mode, BitArray bits, String encoding)
+      throws WriterException {
+    if (mode.equals(Mode.NUMERIC)) {
+      appendNumericBytes(content, bits);
+    } else if (mode.equals(Mode.ALPHANUMERIC)) {
+      appendAlphanumericBytes(content, bits);
+    } else if (mode.equals(Mode.BYTE)) {
+      append8BitBytes(content, bits, encoding);
+    } else if (mode.equals(Mode.KANJI)) {
+      appendKanjiBytes(content, bits);
+    } else {
+      throw new WriterException("Invalid mode: " + mode);
+    }
+  }
+
+  static void appendNumericBytes(String content, BitArray bits) {
+    int length = content.length();
+    int i = 0;
+    while (i < length) {
+      int num1 = content.charAt(i) - '0';
+      if (i + 2 < length) {
+        // Encode three numeric letters in ten bits.
+        int num2 = content.charAt(i + 1) - '0';
+        int num3 = content.charAt(i + 2) - '0';
+        bits.appendBits(num1 * 100 + num2 * 10 + num3, 10);
+        i += 3;
+      } else if (i + 1 < length) {
+        // Encode two numeric letters in seven bits.
+        int num2 = content.charAt(i + 1) - '0';
+        bits.appendBits(num1 * 10 + num2, 7);
+        i += 2;
+      } else {
+        // Encode one numeric letter in four bits.
+        bits.appendBits(num1, 4);
+        i++;
+      }
+    }
+  }
+
+  static void appendAlphanumericBytes(String content, BitArray bits) throws WriterException {
+    int length = content.length();
+    int i = 0;
+    while (i < length) {
+      int code1 = getAlphanumericCode(content.charAt(i));
+      if (code1 == -1) {
+        throw new WriterException();
+      }
+      if (i + 1 < length) {
+        int code2 = getAlphanumericCode(content.charAt(i + 1));
+        if (code2 == -1) {
+          throw new WriterException();
+        }
+        // Encode two alphanumeric letters in 11 bits.
+        bits.appendBits(code1 * 45 + code2, 11);
+        i += 2;
+      } else {
+        // Encode one alphanumeric letter in six bits.
+        bits.appendBits(code1, 6);
+        i++;
+      }
+    }
+  }
+
+  static void append8BitBytes(String content, BitArray bits, String encoding)
+      throws WriterException {
+    byte[] bytes;
+    try {
+      bytes = content.getBytes(encoding);
+    } catch (UnsupportedEncodingException uee) {
+      throw new WriterException(uee.toString());
+    }
+    for (int i = 0; i < bytes.length; ++i) {
+      bits.appendBits(bytes[i], 8);
+    }
+  }
+
+  static void appendKanjiBytes(String content, BitArray bits) throws WriterException {
+    byte[] bytes;
+    try {
+      bytes = content.getBytes("Shift_JIS");
+    } catch (UnsupportedEncodingException uee) {
+      throw new WriterException(uee.toString());
+    }
+    int length = bytes.length;
+    for (int i = 0; i < length; i += 2) {
+      int byte1 = bytes[i] & 0xFF;
+      int byte2 = bytes[i + 1] & 0xFF;
+      int code = (byte1 << 8) | byte2;
+      int subtracted = -1;
+      if (code >= 0x8140 && code <= 0x9ffc) {
+        subtracted = code - 0x8140;
+      } else if (code >= 0xe040 && code <= 0xebbf) {
+        subtracted = code - 0xc140;
+      }
+      if (subtracted == -1) {
+        throw new WriterException("Invalid byte sequence");
+      }
+      int encoded = ((subtracted >> 8) * 0xc0) + (subtracted & 0xff);
+      bits.appendBits(encoded, 13);
+    }
+  }
+
+  private static void appendECI(ECI eci, BitArray bits) {
+    bits.appendBits(Mode.ECI.getBits(), 4);
+    // This is correct for values up to 127, which is all we need now.
+    bits.appendBits(eci.getValue(), 8);
+  }
+
+}