Removed support for dual analog hall effect sensors for shifters

Change-Id: Ie521511f5181140de44c35385aac0b01b5116c06
diff --git a/frc971/shifter_hall_effect.h b/frc971/shifter_hall_effect.h
index aaa5ebd..991386d 100644
--- a/frc971/shifter_hall_effect.h
+++ b/frc971/shifter_hall_effect.h
@@ -4,18 +4,31 @@
 namespace frc971 {
 namespace constants {
 
-// Contains the voltages for an analog hall effect sensor on a shifter.
+// Contains the constants for mapping the analog voltages that the shifter
+// sensors return to the shifter position.  The code which uses this is trying
+// to sort out if we are in low gear, high gear, or neutral.
 struct ShifterHallEffect {
-  // The numbers to use for scaling raw voltages to 0-1.
-  // Low is near 0.0, high is near 1.0
-  double low_gear_middle, low_gear_low;
-  double high_gear_high, high_gear_middle;
+  // low_gear_low is the voltage that the shifter position sensor reads when it
+  // is all the way in low gear.  high_gear_high is the voltage that the shifter
+  // position sensor reads when it is all the way in high gear.  These two
+  // values are used to calculate a position from 0 to 1, where we get 0 when
+  // the shifter is in low gear, and 1 when it is high gear.
+  double low_gear_low;
+  double high_gear_high;
 
   // The numbers for when the dog is clear of each gear.
+  // We are in low gear when the position is less than clear_low, and in high
+  // gear when the shifter position is greater than clear_high.
   double clear_low, clear_high;
 };
 
-} // constants
-} // frc971
+struct DualHallShifterHallEffect {
+  ShifterHallEffect shifter_hall_effect;
+  double low_gear_middle;
+  double high_gear_middle;
+};
+
+}  // namespace constants
+}  // namespace frc971
 
 #endif