From f854442c798201d7af306114ba3ea00070d3828f Mon Sep 17 00:00:00 2001
From: Damjan Adamic <projectkk2glider@gmail.com>
Date: Tue, 10 Nov 2015 17:24:49 +0100
Subject: [PATCH] Fixes #3047: * negative altitude on top bar was displayed
 wrong (same bug affected vertical speed) * add ability to select an altitude
 sensor with ft unit for top bar * display actual sensor unit for top bar
 altitude

---
 radio/src/gui/Taranis/menu_model_telemetry.cpp | 10 +++-------
 radio/src/gui/Taranis/view_main.cpp            |  2 +-
 radio/src/myeeprom.h                           |  4 ++--
 radio/src/telemetry/telemetry.cpp              |  8 ++++++--
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/radio/src/gui/Taranis/menu_model_telemetry.cpp b/radio/src/gui/Taranis/menu_model_telemetry.cpp
index cf5de4cbd..2fa9db275 100644
--- a/radio/src/gui/Taranis/menu_model_telemetry.cpp
+++ b/radio/src/gui/Taranis/menu_model_telemetry.cpp
@@ -164,12 +164,8 @@ enum SensorFields {
 
 bool isSensorUnit(int sensor, uint8_t unit)
 {
-  if (sensor == 0)
-    return true;
-
-  sensor -= 1;
-
-  return g_model.telemetrySensors[sensor].unit == unit;
+  if (sensor <= 0 || sensor > MAX_SENSORS ) return true;
+  return g_model.telemetrySensors[--sensor].unit == unit;
 }
 
 bool isCellsSensor(int sensor)
@@ -184,7 +180,7 @@ bool isGPSSensor(int sensor)
 
 bool isAltSensor(int sensor)
 {
-  return isSensorUnit(sensor, UNIT_DIST);
+  return isSensorUnit(sensor, UNIT_DIST) || isSensorUnit(sensor, UNIT_FEET);
 }
 
 bool isVoltsSensor(int sensor)
diff --git a/radio/src/gui/Taranis/view_main.cpp b/radio/src/gui/Taranis/view_main.cpp
index 2c1f292f3..a4d7e7cb2 100644
--- a/radio/src/gui/Taranis/view_main.cpp
+++ b/radio/src/gui/Taranis/view_main.cpp
@@ -254,7 +254,7 @@ void displayTopBar()
         if (altitudeItem.isAvailable()) {
           LCD_ICON(altitude_icon_x, BAR_Y, ICON_ALTITUDE);
           int32_t value = altitudeItem.value / g_model.telemetrySensors[item].getPrecDivisor();
-          putsValueWithUnit(altitude_icon_x+2*FW-1, BAR_Y+1, value, UNIT_METERS, LEFT);
+          putsValueWithUnit(altitude_icon_x+2*FW-1, BAR_Y+1, value, g_model.telemetrySensors[item].unit, LEFT);
         }
       }
     }
diff --git a/radio/src/myeeprom.h b/radio/src/myeeprom.h
index 5882ca4d3..6d4918799 100644
--- a/radio/src/myeeprom.h
+++ b/radio/src/myeeprom.h
@@ -1317,8 +1317,8 @@ PACK(typedef struct {
   int32_t getValue(int32_t value, uint8_t unit, uint8_t prec) const;
   bool isConfigurable() const;
   bool isPrecConfigurable() const;
-  uint32_t getPrecMultiplier() const;
-  uint32_t getPrecDivisor() const;
+  int32_t getPrecMultiplier() const;
+  int32_t getPrecDivisor() const;
 }) TelemetrySensor;
 #endif
 
diff --git a/radio/src/telemetry/telemetry.cpp b/radio/src/telemetry/telemetry.cpp
index bbde9fd95..4f790fff9 100644
--- a/radio/src/telemetry/telemetry.cpp
+++ b/radio/src/telemetry/telemetry.cpp
@@ -647,14 +647,18 @@ bool TelemetrySensor::isPrecConfigurable() const
   }
 }
 
-uint32_t TelemetrySensor::getPrecMultiplier() const
+int32_t TelemetrySensor::getPrecMultiplier() const
 {
+  /*
+    Important: the return type must be signed, otherwise
+    mathematic operations with a negative telemetry value won't work
+  */
   if (prec == 2) return 1;
   if (prec == 1) return 10;
   return 100;
 }
 
-uint32_t TelemetrySensor::getPrecDivisor() const
+int32_t TelemetrySensor::getPrecDivisor() const
 {
   if (prec == 2) return 100;
   if (prec == 1) return 10;