Report correct Altitude for Mode C message

See rsadsb#13

Signed-off-by: wcampbell <wcampbell1995@gmail.com>

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix [#11](https://github.com/wcampbell0x2a/adsb_deku/issues/11) and [#12](https://github.com/wcampbell0x2a/adsb_deku/issues/12) - Add `ME::NoPosition` and `fmt::Display`
 - Add `fmt::Display` for `ME::Reserved0`
 - Add `fmt::Display` for `ME::Reserved1`
+- Fix [#13](https://github.com/wcampbell0x2a/adsb_deku/issues/13) - Correct Altitude for Mode C Messages, thanks ([@wiseman](https://github.com/wiseman))
 
 ### Apps
 - [radar] Enforce minimum constraint on size of tab text

src/lib.rs

@@ -432,13 +432,10 @@ pub struct Altitude {
 impl std::fmt::Display for Altitude {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         writeln!(f, "  Altitude:      {} ft barometric", self.alt)?;
-        // TODO: fix me
         writeln!(f, "  CPR type:      Airborne")?;
         writeln!(f, "  CPR odd flag:  {}", self.odd_flag)?;
         writeln!(f, "  CPR latitude:  ({})", self.lat_cpr)?;
         writeln!(f, "  CPR longitude: ({})", self.lon_cpr)?;
-        // TODO: fix me
-        //println!("{}", self.t);
         Ok(())
     }
 }
@@ -450,20 +447,13 @@ impl Altitude {
         let q = num & 0x10;
 
         if q > 0 {
-            // regular
-            // TODO this is meters?
             let n = ((num & 0x0fe0) >> 1) | (num & 0x000f);
             let n = n * 25;
-            if n > 1000 {
-                Ok((rest, (n - 1000) as u32))
-            } else {
-                // TODO add error
-                Ok((rest, 0))
-            }
+            Ok((rest, (n - 1000) as u32))
         } else {
-            // mode c?
-            // TODO this is feet
-            let n = ((num & 0x0fc0) << 1) | (num & 0x003f);
+            let mut n = ((num & 0x0fc0) << 1) | (num & 0x003f);
+            n = mode_ac::decode_id13_field(n);
+            n = mode_ac::mode_a_to_mode_c(n).unwrap();
             Ok((rest, ((n as u32) * 100)))
         }
     }
@@ -648,11 +638,6 @@ mod mode_ac {
             one_hundreds = 6 - one_hundreds;
         }
 
-        // Check for invalid one_hundres
-        if one_hundreds < 13 {
-            return Err("Invalid one_hundred");
-        }
-
         Ok((five_hundreds * 5) + one_hundreds - 13)
     }
 }

tests/test.rs

@@ -759,3 +759,80 @@ fn fix_issue_unknown() {
     );
 }
 
+#[test]
+fn fix_issue_13() {
+    // 1
+    let bytes = hex!("8dab92a2593e0664204c69d8fe84");
+    let frame = Frame::from_bytes((&bytes, 0)).unwrap().1;
+    let resulting_string = format!("{}", frame);
+    assert_eq!(
+        r#" Extended Squitter Airborne position (barometric altitude)
+  Address:       ab92a2 (Mode S / ADS-B)
+  Air/Ground:    airborne
+  Altitude:      10600 ft barometric
+  CPR type:      Airborne
+  CPR odd flag:  odd
+  CPR latitude:  (78352)
+  CPR longitude: (19561)
+"#,
+        resulting_string
+    );
+
+    // 2
+    let bytes = hex!("8dab92a299105e93001486608c6d");
+    let frame = Frame::from_bytes((&bytes, 0)).unwrap().1;
+    let resulting_string = format!("{}", frame);
+    assert_eq!(
+        r#" Extended Squitter Airborne velocity over ground, subsonic
+  Address:       ab92a2 (Mode S / ADS-B)
+  Air/Ground:    airborne
+  GNSS delta:    -125 ft
+  Heading:       149
+  Speed:         177 kt groundspeed
+  Vertical rate: 256 ft/min barometric
+"#,
+        resulting_string
+    );
+
+    // 3
+    let bytes = hex!("020007a0d08ff4");
+    let frame = Frame::from_bytes((&bytes, 0)).unwrap().1;
+    let resulting_string = format!("{}", frame);
+    assert_eq!(
+        r#" Short Air-Air Surveillance
+  ICAO Address:  ab92a2 (Mode S / ADS-B)
+  Air/Ground:    airborne?
+  Altitude:      10600 ft barometric
+"#,
+        resulting_string
+    );
+
+    // 4
+    let bytes = hex!("5dab92a2b04912");
+    let frame = Frame::from_bytes((&bytes, 0)).unwrap().1;
+    let resulting_string = format!("{}", frame);
+    assert_eq!(
+        r#" All Call Reply
+  ICAO Address:  ab92a2 (Mode S / ADS-B)
+  Air/Ground:    airborne
+"#,
+        resulting_string
+    );
+
+    // 4
+    let bytes = hex!("8dab92a2593e0664204c69d8fe84");
+    let frame = Frame::from_bytes((&bytes, 0)).unwrap().1;
+    let resulting_string = format!("{}", frame);
+    assert_eq!(
+        r#" Extended Squitter Airborne position (barometric altitude)
+  Address:       ab92a2 (Mode S / ADS-B)
+  Air/Ground:    airborne
+  Altitude:      10600 ft barometric
+  CPR type:      Airborne
+  CPR odd flag:  odd
+  CPR latitude:  (78352)
+  CPR longitude: (19561)
+"#,
+        resulting_string
+    );
+}