1 files changed, 171 insertions, 0 deletions
diff --git a/libraries/zxing/src/com/google/zxing/qrcode/decoder/FormatInformation.java b/libraries/zxing/src/com/google/zxing/qrcode/decoder/FormatInformation.java
new file mode 100644
index 000000000..1b76b0de5
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+++ b/libraries/zxing/src/com/google/zxing/qrcode/decoder/FormatInformation.java
@@ -0,0 +1,171 @@
+/*
+ * Copyright 2007 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.decoder;
+
+/**
+ * <p>Encapsulates a QR Code's format information, including the data mask used and
+ * error correction level.</p>
+ *
+ * @author Sean Owen
+ * @see DataMask
+ * @see ErrorCorrectionLevel
+ */
+final class FormatInformation {
+
+  private static final int FORMAT_INFO_MASK_QR = 0x5412;
+
+  /**
+   * See ISO 18004:2006, Annex C, Table C.1
+   */
+  private static final int[][] FORMAT_INFO_DECODE_LOOKUP = {
+      {0x5412, 0x00},
+      {0x5125, 0x01},
+      {0x5E7C, 0x02},
+      {0x5B4B, 0x03},
+      {0x45F9, 0x04},
+      {0x40CE, 0x05},
+      {0x4F97, 0x06},
+      {0x4AA0, 0x07},
+      {0x77C4, 0x08},
+      {0x72F3, 0x09},
+      {0x7DAA, 0x0A},
+      {0x789D, 0x0B},
+      {0x662F, 0x0C},
+      {0x6318, 0x0D},
+      {0x6C41, 0x0E},
+      {0x6976, 0x0F},
+      {0x1689, 0x10},
+      {0x13BE, 0x11},
+      {0x1CE7, 0x12},
+      {0x19D0, 0x13},
+      {0x0762, 0x14},
+      {0x0255, 0x15},
+      {0x0D0C, 0x16},
+      {0x083B, 0x17},
+      {0x355F, 0x18},
+      {0x3068, 0x19},
+      {0x3F31, 0x1A},
+      {0x3A06, 0x1B},
+      {0x24B4, 0x1C},
+      {0x2183, 0x1D},
+      {0x2EDA, 0x1E},
+      {0x2BED, 0x1F},
+  };
+
+  /**
+   * Offset i holds the number of 1 bits in the binary representation of i
+   */
+  private static final int[] BITS_SET_IN_HALF_BYTE =
+      {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4};
+
+  private final ErrorCorrectionLevel errorCorrectionLevel;
+  private final byte dataMask;
+
+  private FormatInformation(int formatInfo) {
+    // Bits 3,4
+    errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
+    // Bottom 3 bits
+    dataMask = (byte) (formatInfo & 0x07);
+  }
+
+  static int numBitsDiffering(int a, int b) {
+    a ^= b; // a now has a 1 bit exactly where its bit differs with b's
+    // Count bits set quickly with a series of lookups:
+    return BITS_SET_IN_HALF_BYTE[a & 0x0F] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 4 & 0x0F)] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 8 & 0x0F)] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 12 & 0x0F)] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 16 & 0x0F)] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 20 & 0x0F)] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 24 & 0x0F)] +
+        BITS_SET_IN_HALF_BYTE[(a >>> 28 & 0x0F)];
+  }
+
+  /**
+   * @param maskedFormatInfo1 format info indicator, with mask still applied
+   * @param maskedFormatInfo2 second copy of same info; both are checked at the same time
+   *  to establish best match
+   * @return information about the format it specifies, or <code>null</code>
+   *  if doesn't seem to match any known pattern
+   */
+  static FormatInformation decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
+    FormatInformation formatInfo = doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2);
+    if (formatInfo != null) {
+      return formatInfo;
+    }
+    // Should return null, but, some QR codes apparently
+    // do not mask this info. Try again by actually masking the pattern
+    // first
+    return doDecodeFormatInformation(maskedFormatInfo1 ^ FORMAT_INFO_MASK_QR,
+                                     maskedFormatInfo2 ^ FORMAT_INFO_MASK_QR);
+  }
+
+  private static FormatInformation doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
+    // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
+    int bestDifference = Integer.MAX_VALUE;
+    int bestFormatInfo = 0;
+    for (int i = 0; i < FORMAT_INFO_DECODE_LOOKUP.length; i++) {
+      int[] decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
+      int targetInfo = decodeInfo[0];
+      if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
+        // Found an exact match
+        return new FormatInformation(decodeInfo[1]);
+      }
+      int bitsDifference = numBitsDiffering(maskedFormatInfo1, targetInfo);
+      if (bitsDifference < bestDifference) {
+        bestFormatInfo = decodeInfo[1];
+        bestDifference = bitsDifference;
+      }
+      if (maskedFormatInfo1 != maskedFormatInfo2) {
+        // also try the other option
+        bitsDifference = numBitsDiffering(maskedFormatInfo2, targetInfo);
+        if (bitsDifference < bestDifference) {
+          bestFormatInfo = decodeInfo[1];
+          bestDifference = bitsDifference;
+        }
+      }
+    }
+    // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
+    // differing means we found a match
+    if (bestDifference <= 3) {
+      return new FormatInformation(bestFormatInfo);
+    }
+    return null;
+  }
+
+  ErrorCorrectionLevel getErrorCorrectionLevel() {
+    return errorCorrectionLevel;
+  }
+
+  byte getDataMask() {
+    return dataMask;
+  }
+
+  public int hashCode() {
+    return (errorCorrectionLevel.ordinal() << 3) | (int) dataMask;
+  }
+
+  public boolean equals(Object o) {
+    if (!(o instanceof FormatInformation)) {
+      return false;
+    }
+    FormatInformation other = (FormatInformation) o;
+    return this.errorCorrectionLevel == other.errorCorrectionLevel &&
+        this.dataMask == other.dataMask;
+  }
+
+}