Add MAXIMUM_VALID_AMOTION_EVENT_AXIS_VALUE

This helps to standardize checks for the max possible motion event axis
value.

Bug: 32830165
Test: static assert added
Change-Id: I664ee86b065745720a1af4d07c577eb088525d3d
diff --git a/include/android/input.h b/include/android/input.h
index 7080386..d906af6 100644
--- a/include/android/input.h
+++ b/include/android/input.h
@@ -772,8 +772,17 @@
      */
     AMOTION_EVENT_AXIS_GENERIC_16 = 47,
 
+    /**
+     * Note: This is not an "Axis constant". It does not represent any axis, nor should it be used
+     * to represent any axis. It is a constant holding the value of the largest defined axis value,
+     * to make some computations (like iterating through all possible axes) cleaner.
+     * Please update the value accordingly if you add a new axis.
+     */
+    AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE = AMOTION_EVENT_AXIS_GENERIC_16,
+
     // NOTE: If you add a new axis here you must also add it to several other files.
     //       Refer to frameworks/base/core/java/android/view/MotionEvent.java for the full list.
+    //       Update AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE accordingly as well.
 };
 
 /**
diff --git a/services/inputflinger/InputCommonConverter.cpp b/services/inputflinger/InputCommonConverter.cpp
index 8aee39f..23b6f57 100644
--- a/services/inputflinger/InputCommonConverter.cpp
+++ b/services/inputflinger/InputCommonConverter.cpp
@@ -263,6 +263,8 @@
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_14) == common::Axis::GENERIC_14);
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_15) == common::Axis::GENERIC_15);
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_16) == common::Axis::GENERIC_16);
+static_assert(static_cast<common::Axis>(AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE) ==
+              static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_16));
 
 static common::VideoFrame getHalVideoFrame(const TouchVideoFrame& frame) {
     common::VideoFrame out;
diff --git a/services/inputflinger/reader/mapper/JoystickInputMapper.cpp b/services/inputflinger/reader/mapper/JoystickInputMapper.cpp
index 7d30d0c..17f139f 100644
--- a/services/inputflinger/reader/mapper/JoystickInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/JoystickInputMapper.cpp
@@ -145,12 +145,12 @@
         for (auto it = mAxes.begin(); it != mAxes.end(); /*increment it inside loop*/) {
             Axis& axis = it->second;
             if (axis.axisInfo.axis < 0) {
-                while (nextGenericAxisId <= AMOTION_EVENT_AXIS_GENERIC_16 &&
+                while (nextGenericAxisId <= AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE &&
                        haveAxis(nextGenericAxisId)) {
                     nextGenericAxisId += 1;
                 }
 
-                if (nextGenericAxisId <= AMOTION_EVENT_AXIS_GENERIC_16) {
+                if (nextGenericAxisId <= AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE) {
                     axis.axisInfo.axis = nextGenericAxisId;
                     nextGenericAxisId += 1;
                 } else {