Bugfix: cycling sensors report wheel count as UINT32.

Garmin Speed Sensor 2 actually counts forward: it was an UINT16 overflow problem (removed workaround).

Fixes #810.

README_TESTED_SENSORS.md

@@ -23,8 +23,6 @@ However, often only one value is provided.
   * Has updatable firmware that requires an account for garmin.com
   * This sensor reports speed data as cadence.
     A workaround is in place.
-  * This sensor sometimes counts backwards (unknown software version).
-    A workaround is in place.
 
 * Wahoo Speed (Model: WFRPMSPD)
 

src/androidTest/java/de/dennisguse/opentracks/util/UintUtilsTest.java

@@ -0,0 +1,23 @@
+package de.dennisguse.opentracks.util;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class UintUtilsTest {
+
+    @Test
+    public void diff() {
+        assertEquals(0, UintUtils.diff(1, 1, UintUtils.UINT16_MAX));
+        assertEquals(1, UintUtils.diff(2, 1, UintUtils.UINT16_MAX));
+        assertEquals(3, UintUtils.diff(5, 2, UintUtils.UINT16_MAX));
+        assertEquals(65534, UintUtils.diff(1, 2, UintUtils.UINT16_MAX));
+
+        assertEquals(65530, UintUtils.diff(UintUtils.UINT16_MAX, 5, UintUtils.UINT16_MAX));
+    }
+
+    @Test
+    public void realData() {
+        assertEquals(3, UintUtils.diff(381616, 381615, UintUtils.UINT32_MAX));
+    }
+}

src/main/java/de/dennisguse/opentracks/content/sensor/SensorDataCycling.java

@@ -15,8 +15,6 @@ import de.dennisguse.opentracks.util.UnitConversions;
 
 /**
  * Provides cadence in rpm and speed in milliseconds from Bluetooth LE Cycling Cadence and Speed sensors.
- * <p>
- * https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=261449
  */
 public final class SensorDataCycling {
 
@@ -96,7 +94,7 @@ public final class SensorDataCycling {
 
     public static class DistanceSpeed extends SensorData<DistanceSpeed.Data> {
 
-        private final Integer wheelRevolutionsCount; // UINT16
+        private final Integer wheelRevolutionsCount; // UINT32
         private final Integer wheelRevolutionsTime; // UINT16; 1/1024s
 
         public DistanceSpeed(String sensorAddress) {
@@ -133,8 +131,7 @@ public final class SensorDataCycling {
                     return;
                 }
 
-                long wheelDiff = UintUtils.diff(wheelRevolutionsCount, previous.wheelRevolutionsCount, UintUtils.UINT16_MAX);
-                wheelDiff = Math.abs(wheelDiff); //HACK for Garmin Speed 2 as some of those seem to count backwards
+                long wheelDiff = UintUtils.diff(wheelRevolutionsCount, previous.wheelRevolutionsCount, UintUtils.UINT32_MAX);
 
                 Distance distance = wheelCircumference.multipliedBy(wheelDiff);
                 Distance distanceOverall = distance;
@@ -164,11 +161,11 @@ public final class SensorDataCycling {
             if (!(obj instanceof DistanceSpeed)) return false;
 
             DistanceSpeed comp = (DistanceSpeed) obj;
-            if (hasData() && comp.hasData() == hasData()) {
-                return getWheelRevolutionsCount() == comp.getWheelRevolutionsCount() && getWheelRevolutionsTime() == comp.getWheelRevolutionsTime();
-            } else {
+            if (!(hasData() && comp.hasData())) {
                 return false;
             }
+
+            return getWheelRevolutionsCount() == comp.getWheelRevolutionsCount() && getWheelRevolutionsTime() == comp.getWheelRevolutionsTime();
         }
 
         public static class Data {

src/main/java/de/dennisguse/opentracks/util/StringUtils.java

@@ -215,7 +215,7 @@ public class StringUtils {
         }
 
         StringBuilder builder = new StringBuilder();
-        builder.append("[").append(category).append("]");
+        builder.append(getCategory(category));
         if (description != null && description.length() != 0) {
             builder.append(" ").append(description);
         }

src/main/java/de/dennisguse/opentracks/util/UintUtils.java

@@ -11,14 +11,14 @@ public class UintUtils {
     /**
      * Computes a - b for UINT with overflow (b < a).
      *
-     * @return diff or -1 (invalid)
+     * @return diff
      */
     public static long diff(long a, long b, final long UINT_MAX) {
         if (a < 0 || b < 0) {
-            return -1;
+            throw new RuntimeException("a or b cannot be less than zero.");
         }
         if (a > UINT_MAX || b > UINT_MAX) {
-            return -1;
+            throw new RuntimeException("a or b are outside of the allowed range." + a + " " + b);
         }
 
         if (a >= b) {