From 3c14579040bcbe88bc4b5219eebc8de4aab339ab Mon Sep 17 00:00:00 2001
From: Alexander Hirsch <amhirsch825@gmail.com>
Date: Fri, 17 May 2019 09:45:16 -0700
Subject: [PATCH] velocity default argument for backwards compatibility

---
 pyModeS/decoder/adsb.py      | 12 ++++++++----
 pyModeS/decoder/bds/bds06.py | 13 ++++++++++---
 pyModeS/decoder/bds/bds09.py | 12 ++++++++++--
 3 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/pyModeS/decoder/adsb.py b/pyModeS/decoder/adsb.py
index 521ce1d..9253ee5 100644
--- a/pyModeS/decoder/adsb.py
+++ b/pyModeS/decoder/adsb.py
@@ -143,12 +143,16 @@ def altitude(msg):
         return None
 
 
-def velocity(msg):
+def velocity(msg, rtn_sources=False):
     """Calculate the speed, heading, and vertical rate
     (handles both airborne or surface message)
 
     Args:
         msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
 
     Returns:
         (int, float, int, string, string, string): speed (kt),
@@ -160,14 +164,14 @@ def velocity(msg):
             barometer, 'GNSS' for GNSS constellation).
             
             In the case of surface messages, None will be put in place
-            for direction, vertical rate, and their respective sources.
+            for vertical rate and its respective sources.
     """
 
     if 5 <= typecode(msg) <= 8:
-        return surface_velocity(msg)
+        return surface_velocity(msg, rtn_sources)
 
     elif typecode(msg) == 19:
-        return airborne_velocity(msg)
+        return airborne_velocity(msg, rtn_sources)
 
     else:
         raise RuntimeError("incorrect or inconsistant message types, expecting 4<TC<9 or TC=19")
diff --git a/pyModeS/decoder/bds/bds06.py b/pyModeS/decoder/bds/bds06.py
index 8b9df07..d387696 100644
--- a/pyModeS/decoder/bds/bds06.py
+++ b/pyModeS/decoder/bds/bds06.py
@@ -141,13 +141,17 @@ def surface_position_with_ref(msg, lat_ref, lon_ref):
     return round(lat, 5), round(lon, 5)
 
 
-def surface_velocity(msg):
+def surface_velocity(msg, rtn_sources=False):
     """Decode surface velocity from from a surface position message
     Args:
         msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
 
     Returns:
-        (int, float, None, string, string, None): speed (kt),
+        (int, float, int, string, string, None): speed (kt),
             ground track (degree), None for rate of climb/descend (ft/min),
             and speed type ('GS' for ground speed), direction source
             ('gnd_trk' for ground track), None rate of climb/descent source.
@@ -183,4 +187,7 @@ def surface_velocity(msg):
         spd = kts[i-1] + (mov-movs[i-1]) * step
         spd = round(spd, 2)
 
-    return spd, trk, None, 'GS', 'gnd_trk', None
+    if rtn_sources:
+        return spd, trk, 0, 'GS', 'gnd_trk', None
+    else:
+        return spd, trk, 0, 'GS'
diff --git a/pyModeS/decoder/bds/bds09.py b/pyModeS/decoder/bds/bds09.py
index 8a3a384..50ec8e2 100644
--- a/pyModeS/decoder/bds/bds09.py
+++ b/pyModeS/decoder/bds/bds09.py
@@ -25,11 +25,15 @@ from pyModeS.decoder import common
 import math
 
 
-def airborne_velocity(msg):
+def airborne_velocity(msg, rtn_sources=False):
     """Calculate the speed, track (or heading), and vertical rate
 
     Args:
         msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
 
     Returns:
         (int, float, int, string, string, string): speed (kt),
@@ -96,7 +100,11 @@ def airborne_velocity(msg):
     vr = common.bin2int(mb[37:46])
     rocd = None if vr==0 else int(vr_sign*(vr-1)*64)
 
-    return spd, trk_or_hdg, rocd, tag, dir_type, vr_source
+    if rtn_sources:
+        return spd, trk_or_hdg, rocd, tag, dir_type, vr_source
+    else:
+        return spd, trk_or_hdg, rocd, tag
+    
 
 def altitude_diff(msg):
     """Decode the differece between GNSS and barometric altitude