Add unit to lua getFieldInfo (#4750)

* Create getUnit lua function

* Cosmetics

* Expend getFieldInfo instead of creating a new function

* Streamline units table

* @projeckk2glider comments

* Cosmetics

* Use simple division

radio/src/lua/api_general.cpp

@@ -478,10 +478,12 @@ static int luaCrossfireTelemetryPush(lua_State * L)
 Return detailed information about field (source)
 
 The list of valid sources is available:
-* for OpenTX 2.0.x at http://downloads-20.open-tx.org/firmware/lua_fields.txt
+
-* for OpenTX 2.1.x at http://downloads-21.open-tx.org/firmware/lua_fields.txt (depreciated)
+| OpenTX Version | Radio |
-* for OpenTX 2.1.x Taranis and Taranis Plus at http://downloads-21.open-tx.org/firmware/lua_fields_taranis.txt
+|----------------|-------|
-* for OpenTX 2.1.x Taranis X9E at http://downloads-21.open-tx.org/firmware/lua_fields_taranis_x9e.txt
+| 2.0 | [all](http://downloads-20.open-tx.org/firmware/lua_fields.txt) |
+| 2.1 | [X9D and X9D+](http://downloads-21.open-tx.org/firmware/lua_fields_taranis.txt), [X9E](http://downloads-21.open-tx.org/firmware/lua_fields_taranis_x9e.txt) |
+| 2.2 | [X9D and X9D+](http://downloads.open-tx.org/2.2/firmware/lua_fields_x9d.txt), [X9E](http://downloads.open-tx.org/2.2/firmware/lua_fields_x9e.txt), [Horus](http://downloads.open-tx.org/2.2/firmware/lua_fields_x12s.txt) |
 
 @param name (string) name of the field
 
@@ -489,10 +491,11 @@ The list of valid sources is available:
  * `id`   (number) field identifier
  * `name` (string) field name
  * `desc` (string) field description
+ * 'unit' (number) unit identifier [Full list](../appendix/units.html)
 
 @retval nil the requested field was not found
 
-@status current Introduced in 2.0.8
+@status current Introduced in 2.0.8, 'unit' field added in 2.2.0
 */
 static int luaGetFieldInfo(lua_State * L)
 {
@@ -504,6 +507,13 @@ static int luaGetFieldInfo(lua_State * L)
     lua_pushtableinteger(L, "id", field.id);
     lua_pushtablestring(L, "name", what);
     lua_pushtablestring(L, "desc", field.desc);
+    if (field.id >= MIXSRC_FIRST_TELEM && field.id <= MIXSRC_LAST_TELEM) {
+      TelemetrySensor & telemetrySensor = g_model.telemetrySensors[(int)((field.id-MIXSRC_FIRST_TELEM)/3)];
+      lua_pushtableinteger(L, "unit", telemetrySensor.unit);
+    }
+    else {
+      lua_pushtablenil(L, "unit");
+    }
     return 1;
   }
   return 0;
@@ -663,7 +673,7 @@ Play a numerical value (text to speech)
 
 @param value (number) number to play. Value is interpreted as integer.
 
-@param unit (number) unit identifier (see table todo)
+@param unit (number) unit identifier [Full list]((../appendix/units.html))
 
 @param attributes (unsigned number) possible values:
  * `0 or not present` plays integral part of the number (for a number 123 it plays 123)
@@ -672,37 +682,6 @@ Play a numerical value (text to speech)
 
 @status current Introduced in 2.0.0
 
-
-| 2.2 Unit  | Sound        |
-| --- | ---                |
-| 0   | (no unit played)   |
-| 1   | Volts              |
-| 2   | Amps               |
-| 3   | Milliamps          |
-| 4   | Knots              |
-| 5   | Meters per Second  |
-| 6   | Feet per Second    |
-| 7   | Kilometers per Hour|
-| 8   | Miles per Hour     |
-| 9   | Meters             |
-| 10  | Feet               |
-| 11  | Degrees Celsius    |
-| 12  | Degrees Fahrenheit |
-| 13  | Percent            |
-| 14  | Milliamp Hours     |
-| 15  | Watts              |
-| 16  | Milliwatts         |
-| 17  | DB                 |
-| 18  | RPM                |
-| 19  | Gee                |
-| 20  | Degrees            |
-| 21  | Radians            |
-| 22  | Milliliters        |
-| 23  | Fluid Ounces       |
-| 24  | Hours              |
-| 25  | Minutes            |
-| 26  | Seconds            |
-
 */
 static int luaPlayNumber(lua_State * L)
 {
@@ -1004,14 +983,7 @@ static int luaDefaultStick(lua_State * L)
 
 @param value fed to the sensor
 
-@param unit unit of the sensor.
+@param unit unit of the sensor [Full list](../appendix/units.html)
- * `0 or not present` UNIT_RAW.
- * `!= 0` Valid values are 1 (UNIT_VOLTS), 2 (UNIT_AMPS), 3 (UNIT_MILLIAMPS),
- 4 (UNIT_KTS), 5 (UNIT_METERS_PER_SECOND), 6 (UNIT_FEET_PER_SECOND), 7 (UNIT_KMH), 8 (UNIT_MPH), 9 (UNIT_METERS),
- 10 (UNIT_FEET), 11 (UNIT_CELSIUS), 12 (UNIT_FAHRENHEIT), 13 (UNIT_PERCENT), 14 (UNIT_MAH), 15 (UNIT_WATTS),
- 16 (UNIT_MILLIWATTS), 17 (UNIT_DB), 18 (UNIT_RPMS), 19 (UNIT_G), 20 (UNIT_DEGREE), 21 (UNIT_RADIANS),
- 22 (UNIT_MILLILITERS), 23 (UNIT_FLOZ), 24 (UNIT_HOURS), 25 (UNIT_MINUTES), 26 (UNIT_SECONDS), 27 (UNIT_CELLS),
- 28 (UNIT_DATETIME), 29 (UNIT_GPS), 30 (UNIT_BITFIELD), 31 (UNIT_TEXT)
 
 @param precision the precision of the sensor
  * `0 or not present` no decimal precision.
@@ -1116,7 +1088,7 @@ static int luaGetRSSI(lua_State * L)
 /*luadoc
 @function loadScript(file [, mode], [,env])
 
-Load a Lua script file. This is similar to Lua's own [loadfile()](https://www.lua.org/manual/5.2/manual.html#pdf-loadfile) 
+Load a Lua script file. This is similar to Lua's own [loadfile()](https://www.lua.org/manual/5.2/manual.html#pdf-loadfile)
 API method,  but it uses OpenTx's optional pre-compilation feature to save memory and time during load.
 
 Return values are same as from Lua API loadfile() method: If the script was loaded w/out errors
@@ -1128,20 +1100,20 @@ then the loaded script (or "chunk") is returned as a function. Otherwise, return
 
 @param mode (string) (optional) Controls whether to force loading the text (.lua) or pre-compiled binary (.luac)
   version of the script. By default OTx will load the newest version and compile a new binary if necessary (overwriting any
-  existing .luac version of the same script, and stripping some debug info like line numbers).  
+  existing .luac version of the same script, and stripping some debug info like line numbers).
   You can use `mode` to control the loading behavior more specifically. Possible values are:
    * `b` only binary.
    * `t` only text.
    * `T` (default on simulator) prefer text but load binary if that is the only version available.
    * `bt` (default on radio) either binary or text, whichever is newer (binary preferred when timestamps are equal).
-   * Add `x` to avoid automatic compilation of source file to .luac version.  
+   * Add `x` to avoid automatic compilation of source file to .luac version.
        Eg: "tx", "bx", or "btx".
-   * Add `c` to force compilation of source file to .luac version (even if existing version is newer than source file).  
+   * Add `c` to force compilation of source file to .luac version (even if existing version is newer than source file).
        Eg: "tc" or "btc" (forces "t", overrides "x").
-   * Add `d` to keep extra debug info in the compiled binary.  
+   * Add `d` to keep extra debug info in the compiled binary.
        Eg: "td", "btd", or "tcd" (no effect with just "b" or with "x").
 
-@notice 
+@notice
   Note that you will get an error if you specify `mode` as "b" or "t" and that specific version of the file does not exist (eg. no .luac file when "b" is used).
   Also note that `mode` is NOT passed on to Lua's loader function, so unlike with loadfile() the actual file content is not checked (as if no mode or "bt" were passed to loadfile()).