Another half-percent from specializing some operations on bit arrays

git-svn-id: https://zxing.googlecode.com/svn/trunk@2050 59b500cc-1b3d-0410-9834-0bbf25fbcc57

core/src/com/google/zxing/common/BitArray.java

@@ -78,6 +78,32 @@ public final class BitArray {
     bits[i >> 5] ^= 1 << (i & 0x1F);
   }
 
+  /**
+   * @param from first bit to check
+   * @return index of first bit that is set, starting from the given index, or size if none are set
+   */
+  public int getNextSet(int from) {
+    int size = this.size;
+    if (from >= size) {
+      return size;
+    }
+    int bitsOffset = from >> 5;
+    int currentBits = bits[bitsOffset];
+    int mask = 1 << (from & 0x1F);
+    while ((currentBits & mask) == 0) {
+      if (++from >= size) {
+        break;
+      }
+      if (mask == 0x80000000) {
+        mask = 1;
+        currentBits = bits[++bitsOffset];
+      } else {
+        mask <<= 1;
+      }
+    }
+    return from;
+  }
+
   /**
    * Sets a block of 32 bits, starting at bit i.
    *

core/src/com/google/zxing/common/BitMatrix.java

@@ -144,6 +144,14 @@ public final class BitMatrix {
     return row;
   }
 
+  /**
+   * @param y row to set
+   * @param row {@link BitArray} to copy from
+   */
+  public void setRow(int y, BitArray row) {
+    System.arraycopy(row.getBitArray(), 0, bits, y * rowSize, rowSize);
+  }
+
   /**
    * This is useful in detecting the enclosing rectangle of a 'pure' barcode.
    *

core/src/com/google/zxing/oned/CodaBarReader.java

@@ -66,13 +66,9 @@ public final class CodaBarReader extends OneDReader {
       throws NotFoundException {
     int[] start = findAsteriskPattern(row);
     start[1] = 0; // BAS: settings this to 0 improves the recognition rate somehow?
-    int nextStart = start[1];
-    int end = row.getSize();
-
     // Read off white space    
-    while (nextStart < end && !row.get(nextStart)) {
+    int nextStart = row.getNextSet(start[1]);
-      nextStart++;
+    int end = row.getSize();
-    }
 
     StringBuilder result = new StringBuilder();
     int[] counters = new int[7];
@@ -95,9 +91,7 @@ public final class CodaBarReader extends OneDReader {
       }
 
       // Read off white space
-      while (nextStart < end && !row.get(nextStart)) {
+      nextStart = row.getNextSet(nextStart);
-        nextStart++;
-      }
     } while (nextStart < end); // no fixed end pattern so keep on reading while data is available
 
     // Look for whitespace after pattern:
@@ -157,13 +151,7 @@ public final class CodaBarReader extends OneDReader {
 
   private static int[] findAsteriskPattern(BitArray row) throws NotFoundException {
     int width = row.getSize();
-    int rowOffset = 0;
+    int rowOffset = row.getNextSet(0);
-    while (rowOffset < width) {
-      if (row.get(rowOffset)) {
-        break;
-      }
-      rowOffset++;
-    }
 
     int counterPosition = 0;
     int[] counters = new int[7];
@@ -172,8 +160,7 @@ public final class CodaBarReader extends OneDReader {
     int patternLength = counters.length;
 
     for (int i = rowOffset; i < width; i++) {
-      boolean pixel = row.get(i);
+      if (row.get(i) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == patternLength - 1) {

core/src/com/google/zxing/oned/Code128Reader.java

@@ -168,13 +168,7 @@ public final class Code128Reader extends OneDReader {
 
   private static int[] findStartPattern(BitArray row) throws NotFoundException {
     int width = row.getSize();
-    int rowOffset = 0;
+    int rowOffset = row.getNextSet(0);
-    while (rowOffset < width) {
-      if (row.get(rowOffset)) {
-        break;
-      }
-      rowOffset++;
-    }
 
     int counterPosition = 0;
     int[] counters = new int[6];
@@ -183,8 +177,7 @@ public final class Code128Reader extends OneDReader {
     int patternLength = counters.length;
 
     for (int i = rowOffset; i < width; i++) {
-      boolean pixel = row.get(i);
+      if (row.get(i) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == patternLength - 1) {

core/src/com/google/zxing/oned/Code39Reader.java

@@ -98,13 +98,9 @@ public final class Code39Reader extends OneDReader {
 
     int[] counters = new int[9];
     int[] start = findAsteriskPattern(row, counters);
-    int nextStart = start[1];
-    int end = row.getSize();
-
     // Read off white space    
-    while (nextStart < end && !row.get(nextStart)) {
+    int nextStart = row.getNextSet(start[1]);
-      nextStart++;
+    int end = row.getSize();
-    }
 
     StringBuilder result = new StringBuilder(20);
     char decodedChar;
@@ -122,11 +118,9 @@ public final class Code39Reader extends OneDReader {
         nextStart += counter;
       }
       // Read off white space
-      while (nextStart < end && !row.get(nextStart)) {
+      nextStart = row.getNextSet(nextStart);
-        nextStart++;
-      }
     } while (decodedChar != '*');
-    result.deleteCharAt(result.length() - 1); // remove asterisk
+    result.setLength(result.length() - 1); // remove asterisk
 
     // Look for whitespace after pattern:
     int lastPatternSize = 0;
@@ -136,7 +130,7 @@ public final class Code39Reader extends OneDReader {
     int whiteSpaceAfterEnd = nextStart - lastStart - lastPatternSize;
     // If 50% of last pattern size, following last pattern, is not whitespace, fail
     // (but if it's whitespace to the very end of the image, that's OK)
-    if (nextStart != end && whiteSpaceAfterEnd / 2 < lastPatternSize) {
+    if (nextStart != end && (whiteSpaceAfterEnd >> 1) < lastPatternSize) {
       throw NotFoundException.getNotFoundInstance();
     }
 
@@ -149,7 +143,7 @@ public final class Code39Reader extends OneDReader {
       if (result.charAt(max) != ALPHABET[total % 43]) {
         throw ChecksumException.getChecksumInstance();
       }
-      result.deleteCharAt(max);
+      result.setLength(max);
     }
 
     if (result.length() < 4) {
@@ -178,13 +172,7 @@ public final class Code39Reader extends OneDReader {
 
   private static int[] findAsteriskPattern(BitArray row, int[] counters) throws NotFoundException {
     int width = row.getSize();
-    int rowOffset = 0;
+    int rowOffset = row.getNextSet(0);
-    while (rowOffset < width) {
-      if (row.get(rowOffset)) {
-        break;
-      }
-      rowOffset++;
-    }
 
     int counterPosition = 0;
     int patternStart = rowOffset;
@@ -192,14 +180,13 @@ public final class Code39Reader extends OneDReader {
     int patternLength = counters.length;
 
     for (int i = rowOffset; i < width; i++) {
-      boolean pixel = row.get(i);
+      if (row.get(i) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == patternLength - 1) {
           if (toNarrowWidePattern(counters) == ASTERISK_ENCODING) {
             // Look for whitespace before start pattern, >= 50% of width of start pattern
-            if (row.isRange(Math.max(0, patternStart - (i - patternStart) / 2), patternStart, false)) {
+            if (row.isRange(Math.max(0, patternStart - ((i - patternStart) >> 1)), patternStart, false)) {
               return new int[]{patternStart, i};
             }
           }

core/src/com/google/zxing/oned/Code93Reader.java

@@ -58,13 +58,9 @@ public final class Code93Reader extends OneDReader {
       throws NotFoundException, ChecksumException, FormatException {
 
     int[] start = findAsteriskPattern(row);
-    int nextStart = start[1];
-    int end = row.getSize();
-
     // Read off white space    
-    while (nextStart < end && !row.get(nextStart)) {
+    int nextStart = row.getNextSet(start[1]);
-      nextStart++;
+    int end = row.getSize();
-    }
 
     StringBuilder result = new StringBuilder(20);
     int[] counters = new int[6];
@@ -83,9 +79,7 @@ public final class Code93Reader extends OneDReader {
         nextStart += counter;
       }
       // Read off white space
-      while (nextStart < end && !row.get(nextStart)) {
+      nextStart = row.getNextSet(nextStart);
-        nextStart++;
-      }
     } while (decodedChar != '*');
     result.deleteCharAt(result.length() - 1); // remove asterisk
 
@@ -119,13 +113,7 @@ public final class Code93Reader extends OneDReader {
 
   private static int[] findAsteriskPattern(BitArray row) throws NotFoundException {
     int width = row.getSize();
-    int rowOffset = 0;
+    int rowOffset = row.getNextSet(0);
-    while (rowOffset < width) {
-      if (row.get(rowOffset)) {
-        break;
-      }
-      rowOffset++;
-    }
 
     int counterPosition = 0;
     int[] counters = new int[6];
@@ -134,8 +122,7 @@ public final class Code93Reader extends OneDReader {
     int patternLength = counters.length;
 
     for (int i = rowOffset; i < width; i++) {
-      boolean pixel = row.get(i);
+      if (row.get(i) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == patternLength - 1) {

core/src/com/google/zxing/oned/ITFReader.java

@@ -227,13 +227,7 @@ public final class ITFReader extends OneDReader {
    */
   private static int skipWhiteSpace(BitArray row) throws NotFoundException {
     int width = row.getSize();
-    int endStart = 0;
+    int endStart = row.getNextSet(0);
-    while (endStart < width) {
-      if (row.get(endStart)) {
-        break;
-      }
-      endStart++;
-    }
     if (endStart == width) {
       throw NotFoundException.getNotFoundInstance();
     }
@@ -300,8 +294,7 @@ public final class ITFReader extends OneDReader {
     int counterPosition = 0;
     int patternStart = rowOffset;
     for (int x = rowOffset; x < width; x++) {
-      boolean pixel = row.get(x);
+      if (row.get(x) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == patternLength - 1) {

core/src/com/google/zxing/oned/OneDReader.java

@@ -203,8 +203,7 @@ public abstract class OneDReader implements Reader {
     int counterPosition = 0;
     int i = start;
     while (i < end) {
-      boolean pixel = row.get(i);
+      if (row.get(i) ^ isWhite) { // that is, exactly one is true
-      if (pixel ^ isWhite) { // that is, exactly one is true
         counters[counterPosition]++;
       } else {
         counterPosition++;

core/src/com/google/zxing/oned/UPCEANExtensionSupport.java

@@ -85,9 +85,7 @@ final class UPCEANExtensionSupport {
       }
       if (x != 4) {
         // Read off separator if not last
-        while (rowOffset < end && !row.get(rowOffset)) {
+        rowOffset = row.getNextSet(rowOffset);
-          rowOffset++;
-        }
         while (rowOffset < end && row.get(rowOffset)) {
           rowOffset++;
         }

core/src/com/google/zxing/oned/UPCEANReader.java

@@ -289,8 +289,7 @@ public abstract class UPCEANReader extends OneDReader {
     int counterPosition = 0;
     int patternStart = rowOffset;
     for (int x = rowOffset; x < width; x++) {
-      boolean pixel = row.get(x);
+      if (row.get(x) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == patternLength - 1) {

core/src/com/google/zxing/oned/rss/RSS14Reader.java

@@ -303,8 +303,7 @@ public final class RSS14Reader extends AbstractRSSReader {
     int counterPosition = 0;
     int patternStart = rowOffset;
     for (int x = rowOffset; x < width; x++) {
-      boolean pixel = row.get(x);
+      if (row.get(x) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == 3) {

core/src/com/google/zxing/oned/rss/expanded/RSSExpandedReader.java

@@ -306,8 +306,7 @@ public final class RSSExpandedReader extends AbstractRSSReader {
     int counterPosition = 0;
     int patternStart = rowOffset;
     for (int x = rowOffset; x < width; x++) {
-      boolean pixel = row.get(x);
+      if (row.get(x) ^ isWhite) {
-      if (pixel ^ isWhite) {
         counters[counterPosition]++;
       } else {
         if (counterPosition == 3) {

core/test/src/com/google/zxing/common/BitArrayTestCase.java

@@ -34,6 +34,31 @@ public final class BitArrayTestCase extends Assert {
     }
   }
 
+  @Test
+  public void testGetNextSet() {
+    BitArray array = new BitArray(32);
+    assertEquals(32, array.getNextSet(0));
+    assertEquals(32, array.getNextSet(31));
+
+    array = new BitArray(33);
+    assertEquals(33, array.getNextSet(0));
+    assertEquals(33, array.getNextSet(31));
+    assertEquals(33, array.getNextSet(32));
+
+    array.set(31);
+    assertEquals(31, array.getNextSet(0));
+    assertEquals(31, array.getNextSet(30));
+    assertEquals(31, array.getNextSet(31));
+    assertEquals(33, array.getNextSet(32));
+
+    array = new BitArray(33);
+    array.set(32);
+    assertEquals(32, array.getNextSet(0));
+    assertEquals(32, array.getNextSet(30));
+    assertEquals(32, array.getNextSet(31));
+    assertEquals(32, array.getNextSet(32));
+  }
+
   @Test
   public void testSetBulk() {
     BitArray array = new BitArray(64);