From 84c62555674445ed43181b8c3cca998e2fd82b19 Mon Sep 17 00:00:00 2001
From: boringow <62092582+boringow@users.noreply.github.com>
Date: Tue, 10 Nov 2020 20:44:32 +0100
Subject: [PATCH 1/7] Update allcall.py

Tested, it is all functioning well, I created a new decoder since I couldn't understand yours. It may not be the most optimum, I am quite new into coding so it may no be optimal, but for sure it is working :) Hope you like it!
---
 pyModeS/decoder/allcall.py | 53 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 51 insertions(+), 2 deletions(-)

diff --git a/pyModeS/decoder/allcall.py b/pyModeS/decoder/allcall.py
index 6e296ca..ebd132c 100644
--- a/pyModeS/decoder/allcall.py
+++ b/pyModeS/decoder/allcall.py
@@ -1,5 +1,54 @@
+from pyModeS import common
 """
 Decoding all call replies DF=11
-
-[To be implemented]
 """
+
+
+def ipcode(msg):
+    '''Returns the IP code of the Mode S all-call reply (DF11)'''
+    binaryraw=common.hex2bin(msg)
+    PI=binaryraw[-24:]
+    DATA=binaryraw[:-24]
+
+    Gx='1111111111111010000001001000'
+    Mx=DATA[::-1].zfill(len(DATA)+24)[::-1]
+    initialdifference=len(Mx)-len(Gx)
+    Gx = Gx[::-1].zfill(len(Mx))[::-1]
+    while len(Mx)>initialdifference:
+        MSB=Mx[0]
+        if MSB=='1':
+            result=int(Mx,2)^int(Gx,2)
+            Mx = str(bin(result)[2:])
+            Gx = Gx.rstrip('0')[::-1].zfill(len(Mx))[::-1]
+
+        else: #If the Mx starts with a 0
+            Mx=Mx[1:]
+            Gx=Gx[:-1]
+
+    SIcode=(int(Mx,2)^int(PI,2)) #Mx is the parity sequence and PI is the last field of the DF11.
+    return SIcode
+
+
+def capability(msg):
+    '''return the capability code'''
+    if common.df(msg) == 11:#check that the msg is DF11
+        binaryraw=common.hex2bin(msg)
+        CA = (int(binaryraw[5:8],2))
+        if CA == 0: #level 1 transponder
+            return 0
+        if CA in [1, 2,  3]: #reserved
+            return None
+        if CA == 4:#level 2 transponder, ability to set CA to 7 and on ground
+            return 4
+        if CA == 5:#level 2 transponder, ability to set CA to 7 and airborn
+            return 5
+        if CA == 6:#level 2 transponder, ability to set CA to 7 and either airborn on ground
+            return 6
+        if CA == 7:# (either DR field is 0 or FS field is 2,3,4 or 5), and either airborn on ground
+            return 7
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def AA(msg):
+    '''returns the icao code of the aircraft'''
+    return (msg[2:8])

From 35c0bfa5137c3828341280e33ece3d33334dbefc Mon Sep 17 00:00:00 2001
From: boringow <62092582+boringow@users.noreply.github.com>
Date: Thu, 12 Nov 2020 14:46:33 +0100
Subject: [PATCH 2/7] Update allcall.py

---
 pyModeS/decoder/allcall.py | 75 +++++++++++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 21 deletions(-)

diff --git a/pyModeS/decoder/allcall.py b/pyModeS/decoder/allcall.py
index ebd132c..4e9fdf2 100644
--- a/pyModeS/decoder/allcall.py
+++ b/pyModeS/decoder/allcall.py
@@ -3,31 +3,61 @@ from pyModeS import common
 Decoding all call replies DF=11
 """
 
-
 def ipcode(msg):
-    '''Returns the IP code of the Mode S all-call reply (DF11)'''
-    binaryraw=common.hex2bin(msg)
-    PI=binaryraw[-24:]
-    DATA=binaryraw[:-24]
+    if common.df(msg) == 11:  # check that the msg is DF11
+        '''Returns the IP code of the Mode S all-call reply (DF11)'''
+        binaryraw=common.hex2bin(msg)
+        PI=binaryraw[-24:]
+        DATA=binaryraw[:-24]
 
-    Gx='1111111111111010000001001000'
-    Mx=DATA[::-1].zfill(len(DATA)+24)[::-1]
-    initialdifference=len(Mx)-len(Gx)
-    Gx = Gx[::-1].zfill(len(Mx))[::-1]
-    while len(Mx)>initialdifference:
-        MSB=Mx[0]
-        if MSB=='1':
-            result=int(Mx,2)^int(Gx,2)
-            Mx = str(bin(result)[2:])
-            Gx = Gx.rstrip('0')[::-1].zfill(len(Mx))[::-1]
+        Gx='1111111111111010000001001000'
+        Mx=DATA[::-1].zfill(len(DATA)+24)[::-1]
+        initialdifference=len(Mx)-len(Gx)
+        Gx = Gx[::-1].zfill(len(Mx))[::-1]
+        while len(Mx)>initialdifference:
+            MSB=Mx[0]
+            if MSB=='1':
+                result=int(Mx,2)^int(Gx,2)
+                Mx = str(bin(result)[2:])
+                Gx = Gx.rstrip('0')[::-1].zfill(len(Mx))[::-1]
 
-        else: #If the Mx starts with a 0
-            Mx=Mx[1:]
-            Gx=Gx[:-1]
+            else: #If the Mx starts with a 0
+                Mx=Mx[1:]
+                Gx=Gx[:-1]
 
-    SIcode=(int(Mx,2)^int(PI,2)) #Mx is the parity sequence and PI is the last field of the DF11.
-    return SIcode
+        SIcode=bin(int(Mx,2)^int(PI,2)).zfill(7) #Mx is the parity sequence and PI is the last field of the DF11.
+        if int(SIcode[0:3],2)>0:
+            return str("SI" + str(int(SIcode[3:],2)))
+        else:
+            return str("II" + str(int(SIcode,2)))
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
 
+def flight_status(msg):
+    '''returns the flight status'''
+    if common.df(msg) == 11:  # check that the msg is DF11
+        binaryraw=common.hex2bin(msg)
+        CA = (int(binaryraw[5:8],2))
+        if CA in [0, 1, 2, 3, 6, 7]: #reserved
+            return None
+        if CA == 4:#level 2 transponder, ability to set CA to 7 and on ground
+            return "on ground"
+        if CA == 5:#level 2 transponder, ability to set CA to 7 and airborn
+            return "airborne"
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def transponder_level(msg):
+    '''returns the transponder level'''
+    if common.df(msg) == 11:#check that the msg is DF11
+        binaryraw=common.hex2bin(msg)
+        CA = (int(binaryraw[5:8],2))
+        if CA in [1, 2, 3, 4, 5, 6, 7]: #reserved
+            return 2
+        if CA == 0:
+            return 1
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
 
 def capability(msg):
     '''return the capability code'''
@@ -51,4 +81,7 @@ def capability(msg):
 
 def AA(msg):
     '''returns the icao code of the aircraft'''
-    return (msg[2:8])
+    if common.df(msg) == 11:  # check that the msg is DF11
+        return (msg[2:8])
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")

From 4ba900f500f91ddfe53c098ed9ece6df8942fe12 Mon Sep 17 00:00:00 2001
From: boringow <62092582+boringow@users.noreply.github.com>
Date: Thu, 12 Nov 2020 14:49:52 +0100
Subject: [PATCH 3/7] Update allcall.py

---
 pyModeS/decoder/allcall.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyModeS/decoder/allcall.py b/pyModeS/decoder/allcall.py
index 4e9fdf2..9ecd194 100644
--- a/pyModeS/decoder/allcall.py
+++ b/pyModeS/decoder/allcall.py
@@ -3,7 +3,7 @@ from pyModeS import common
 Decoding all call replies DF=11
 """
 
-def ipcode(msg):
+def interrogator_code(msg):
     if common.df(msg) == 11:  # check that the msg is DF11
         '''Returns the IP code of the Mode S all-call reply (DF11)'''
         binaryraw=common.hex2bin(msg)

From eacc828b75a19ed62cf7df072e610308d3dbc893 Mon Sep 17 00:00:00 2001
From: boringow <62092582+boringow@users.noreply.github.com>
Date: Sat, 14 Nov 2020 09:37:08 +0100
Subject: [PATCH 4/7] Update surv.py

I have completed the allcall.py and the surv.py, but I can not commit the two files at the same time. Hope you like how it looks, If necessary, tell me what could I change. Have a nice weekend!
---
 pyModeS/decoder/surv.py | 117 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 116 insertions(+), 1 deletion(-)

diff --git a/pyModeS/decoder/surv.py b/pyModeS/decoder/surv.py
index 746f47f..abda10d 100644
--- a/pyModeS/decoder/surv.py
+++ b/pyModeS/decoder/surv.py
@@ -1,5 +1,120 @@
 """
 Warpper for short roll call surveillance replies DF=4/5
 
-[To be implemented]
 """
+
+from pyModeS import common
+
+def fs(msg):
+    '''tell the flight status of the aircraft, returns airborne, ground or None'''
+    if common.df(msg) in [4,5]:
+        binaryraw=common.hex2bin(msg)
+        fs=int(binaryraw[5:8],2)
+        if fs in [0,2]:
+            return "airborne"
+        if fs in [1,3]:
+            return "ground"
+        else:
+            return None
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def alert(msg):
+    '''returns True if there is an alert, False otherwise '''
+    #The alert indicates that the TXPPR Mode A code is changed manually by the pilot. Icao Annex10, Vol IV, 3.1.2.6.10.1.1
+    if common.df(msg) in [4,5]:
+        binaryraw = common.hex2bin(msg)
+        fs = int(binaryraw[5:8], 2)
+        if fs in [2,3,4]:
+            return True
+        if fs in [0,1,5]:
+            return False
+        else:
+            return None
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+
+def SPI(msg):
+    '''returns True if there there is Special Pulse Indicator, False otherwise '''
+    if common.df(msg) in [4, 5]:
+        binaryraw = common.hex2bin(msg)
+        fs = int(binaryraw[5:8], 2)
+        if fs in [4, 5]:
+            return True
+        if fs in [0, 1, 2, 3]:
+            return False
+        else:
+            return None
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def dr(msg):
+    '''Returns Downlink Request Status.
+     Args:
+        msg (str): 14 hexdigits string,
+    Returns:
+        str: Downlink Request Status
+    '''
+    if common.df(msg) in [4,5]:
+        binaryraw = common.hex2bin(msg)
+        dr = int(binaryraw[8:13], 2)
+        if dr in [2,3,6,7]:
+            return "ACAS"
+        if dr == 0:
+            return "no downlink request"
+        if dr == 1:
+            return "request to send Comm-B message"
+        if dr in 4:
+            return "Comm-B broadcast 1 available"
+        if dr in 5:
+            return "Comm-B broadcast 2 available"
+        if dr > 7 and dr < 16:
+            return None
+        else:
+            return str(15-dr)+" downlink ELM segments available"
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def um(msg):
+    '''returns the Interrogator Identifier and the type of reservation
+    Args:
+        msg (str): 14 hexdigits string,
+    Returns:
+        int: II code of the identifier that triggered the reply
+        str: type of reservation made by the interrogator
+    '''
+    if common.df(msg) in [4,5]:
+        binaryraw = common.hex2bin(msg)
+        iis = int(binaryraw[13:17], 2)
+        ds = int(binaryraw[17:19], 2)
+        if ds == 0:
+            ds=None
+        if ds == 1:
+            ds='Comm-B'
+        if ds == 2:
+            ds='Comm-C'
+        if ds == 3:
+            ds='Comm-D'
+        return iis, ds
+
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def ac(msg):
+    '''return the altitude in ft'''
+    if common.df(msg) == 4:
+        binaryraw = common.hex2bin(msg)
+        altcode = binaryraw[19:32] # Here we could also put the common.altcode(msg).
+        return common.altitude(altcode)
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")
+
+def id(msg):
+    '''return the squawk code (identifier)'''
+    if common.df(msg) == 5:
+        binaryraw = common.hex2bin(msg)
+        altcode = binaryraw[19:32]  # Here we could also put the common.idcode(msg).
+        return common.squawk(altcode)
+    else:
+        raise RuntimeError("Incorrect or inconsistent message types")

From 668d6580d025b2df436baacd62089a19034484df Mon Sep 17 00:00:00 2001
From: Junzi Sun <junzisun@gmail.com>
Date: Sat, 14 Nov 2020 21:57:08 +0100
Subject: [PATCH 5/7] Update allcall.py

---
 pyModeS/decoder/allcall.py | 140 +++++++++++++++++--------------------
 1 file changed, 64 insertions(+), 76 deletions(-)

diff --git a/pyModeS/decoder/allcall.py b/pyModeS/decoder/allcall.py
index 9ecd194..5f352f4 100644
--- a/pyModeS/decoder/allcall.py
+++ b/pyModeS/decoder/allcall.py
@@ -1,87 +1,75 @@
+"""
+Decode all-call reply messages, with dowlink format 11
+"""
+
 from pyModeS import common
-"""
-Decoding all call replies DF=11
-"""
 
-def interrogator_code(msg):
-    if common.df(msg) == 11:  # check that the msg is DF11
-        '''Returns the IP code of the Mode S all-call reply (DF11)'''
-        binaryraw=common.hex2bin(msg)
-        PI=binaryraw[-24:]
-        DATA=binaryraw[:-24]
 
-        Gx='1111111111111010000001001000'
-        Mx=DATA[::-1].zfill(len(DATA)+24)[::-1]
-        initialdifference=len(Mx)-len(Gx)
-        Gx = Gx[::-1].zfill(len(Mx))[::-1]
-        while len(Mx)>initialdifference:
-            MSB=Mx[0]
-            if MSB=='1':
-                result=int(Mx,2)^int(Gx,2)
-                Mx = str(bin(result)[2:])
-                Gx = Gx.rstrip('0')[::-1].zfill(len(Mx))[::-1]
+def _checkdf(func):
+    """Ensure downlink format is 11."""
 
-            else: #If the Mx starts with a 0
-                Mx=Mx[1:]
-                Gx=Gx[:-1]
+    def wrapper(msg):
+        df = common.df(msg)
+        if df != 11:
+            raise RuntimeError(
+                "Incorrect downlink format, expect 11, got {}".format(df)
+            )
+        return func(msg)
 
-        SIcode=bin(int(Mx,2)^int(PI,2)).zfill(7) #Mx is the parity sequence and PI is the last field of the DF11.
-        if int(SIcode[0:3],2)>0:
-            return str("SI" + str(int(SIcode[3:],2)))
-        else:
-            return str("II" + str(int(SIcode,2)))
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+    return wrapper
 
-def flight_status(msg):
-    '''returns the flight status'''
-    if common.df(msg) == 11:  # check that the msg is DF11
-        binaryraw=common.hex2bin(msg)
-        CA = (int(binaryraw[5:8],2))
-        if CA in [0, 1, 2, 3, 6, 7]: #reserved
-            return None
-        if CA == 4:#level 2 transponder, ability to set CA to 7 and on ground
-            return "on ground"
-        if CA == 5:#level 2 transponder, ability to set CA to 7 and airborn
-            return "airborne"
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
 
-def transponder_level(msg):
-    '''returns the transponder level'''
-    if common.df(msg) == 11:#check that the msg is DF11
-        binaryraw=common.hex2bin(msg)
-        CA = (int(binaryraw[5:8],2))
-        if CA in [1, 2, 3, 4, 5, 6, 7]: #reserved
-            return 2
-        if CA == 0:
-            return 1
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+@_checkdf
+def icao(msg):
+    """Decode transponder code (ICAO address).
 
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        string: ICAO address
+
+    """
+    return common.icao(msg)
+
+
+@_checkdf
+def interrogator(msg):
+    """Decode interrogator identifier code.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int: interrogator identifier code
+
+    """
+    # simply the CRC reminder
+    return common.crc(msg)
+
+
+@_checkdf
 def capability(msg):
-    '''return the capability code'''
-    if common.df(msg) == 11:#check that the msg is DF11
-        binaryraw=common.hex2bin(msg)
-        CA = (int(binaryraw[5:8],2))
-        if CA == 0: #level 1 transponder
-            return 0
-        if CA in [1, 2,  3]: #reserved
-            return None
-        if CA == 4:#level 2 transponder, ability to set CA to 7 and on ground
-            return 4
-        if CA == 5:#level 2 transponder, ability to set CA to 7 and airborn
-            return 5
-        if CA == 6:#level 2 transponder, ability to set CA to 7 and either airborn on ground
-            return 6
-        if CA == 7:# (either DR field is 0 or FS field is 2,3,4 or 5), and either airborn on ground
-            return 7
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+    """Decode transponder capability.
 
-def AA(msg):
-    '''returns the icao code of the aircraft'''
-    if common.df(msg) == 11:  # check that the msg is DF11
-        return (msg[2:8])
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: transponder capability, description
+
+    """
+    msgbin = common.hex2bin(msg)
+    ca = common.bin2int(msgbin[5:8])
+
+    if ca == 0:
+        text = "level 1 transponder"
+    elif ca == 4:
+        text = "level 2 transponder, ability to set CA to 7, on ground"
+    elif ca == 5:
+        text = "level 2 transponder, ability to set CA to 7, airborne"
+    elif ca == 6:
+        text = "evel 2 transponder, ability to set CA to 7, either airborne or ground"
+    elif ca == 7:
+        text = "Downlink Request value is 0,or the Flight Status is 2, 3, 4 or 5, either airborne or on the ground"
     else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+        text = None
+
+    return ca, text

From a3e5e7e1417295187749b86fba5fd5ee4a2ec34d Mon Sep 17 00:00:00 2001
From: Junzi Sun <junzisun@gmail.com>
Date: Sat, 14 Nov 2020 21:57:34 +0100
Subject: [PATCH 6/7] Update surv.py

---
 pyModeS/decoder/surv.py | 228 +++++++++++++++++++++-------------------
 1 file changed, 120 insertions(+), 108 deletions(-)

diff --git a/pyModeS/decoder/surv.py b/pyModeS/decoder/surv.py
index abda10d..ceec90c 100644
--- a/pyModeS/decoder/surv.py
+++ b/pyModeS/decoder/surv.py
@@ -1,120 +1,132 @@
 """
-Warpper for short roll call surveillance replies DF=4/5
-
+Decode short roll call surveillance replies, with downlink format 4 or 5
 """
 
 from pyModeS import common
 
+
+def _checkdf(func):
+    """Ensure downlink format is 4 or 5."""
+
+    def wrapper(msg):
+        df = common.df(msg)
+        if df not in [4, 5]:
+            raise RuntimeError(
+                "Incorrect downlink format, expect 4 or 5, got {}".format(df)
+            )
+        return func(msg)
+
+    return wrapper
+
+
+@_checkdf
 def fs(msg):
-    '''tell the flight status of the aircraft, returns airborne, ground or None'''
-    if common.df(msg) in [4,5]:
-        binaryraw=common.hex2bin(msg)
-        fs=int(binaryraw[5:8],2)
-        if fs in [0,2]:
-            return "airborne"
-        if fs in [1,3]:
-            return "ground"
-        else:
-            return None
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+    """Decode flight status.
 
-def alert(msg):
-    '''returns True if there is an alert, False otherwise '''
-    #The alert indicates that the TXPPR Mode A code is changed manually by the pilot. Icao Annex10, Vol IV, 3.1.2.6.10.1.1
-    if common.df(msg) in [4,5]:
-        binaryraw = common.hex2bin(msg)
-        fs = int(binaryraw[5:8], 2)
-        if fs in [2,3,4]:
-            return True
-        if fs in [0,1,5]:
-            return False
-        else:
-            return None
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
-
-
-def SPI(msg):
-    '''returns True if there there is Special Pulse Indicator, False otherwise '''
-    if common.df(msg) in [4, 5]:
-        binaryraw = common.hex2bin(msg)
-        fs = int(binaryraw[5:8], 2)
-        if fs in [4, 5]:
-            return True
-        if fs in [0, 1, 2, 3]:
-            return False
-        else:
-            return None
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
-
-def dr(msg):
-    '''Returns Downlink Request Status.
-     Args:
-        msg (str): 14 hexdigits string,
-    Returns:
-        str: Downlink Request Status
-    '''
-    if common.df(msg) in [4,5]:
-        binaryraw = common.hex2bin(msg)
-        dr = int(binaryraw[8:13], 2)
-        if dr in [2,3,6,7]:
-            return "ACAS"
-        if dr == 0:
-            return "no downlink request"
-        if dr == 1:
-            return "request to send Comm-B message"
-        if dr in 4:
-            return "Comm-B broadcast 1 available"
-        if dr in 5:
-            return "Comm-B broadcast 2 available"
-        if dr > 7 and dr < 16:
-            return None
-        else:
-            return str(15-dr)+" downlink ELM segments available"
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
-
-def um(msg):
-    '''returns the Interrogator Identifier and the type of reservation
     Args:
-        msg (str): 14 hexdigits string,
+        msg (str): 14 hexdigits string
     Returns:
-        int: II code of the identifier that triggered the reply
-        str: type of reservation made by the interrogator
-    '''
-    if common.df(msg) in [4,5]:
-        binaryraw = common.hex2bin(msg)
-        iis = int(binaryraw[13:17], 2)
-        ds = int(binaryraw[17:19], 2)
-        if ds == 0:
-            ds=None
-        if ds == 1:
-            ds='Comm-B'
-        if ds == 2:
-            ds='Comm-C'
-        if ds == 3:
-            ds='Comm-D'
-        return iis, ds
+        int, str: flight status, description
 
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+    """
+    msgbin = common.hex2bin(msg)
+    fs = common.bin2int(msgbin[5:8])
+    text = None
 
-def ac(msg):
-    '''return the altitude in ft'''
-    if common.df(msg) == 4:
-        binaryraw = common.hex2bin(msg)
-        altcode = binaryraw[19:32] # Here we could also put the common.altcode(msg).
-        return common.altitude(altcode)
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+    if fs == 0:
+        text = "no alert, no SPI, aircraft is airborne"
+    elif fs == 1:
+        text = "no alert, no SPI, aircraft is on-ground"
+    elif fs == 2:
+        text = "alert, no SPI, aircraft is airborne"
+    elif fs == 3:
+        text = "alert, no SPI, aircraft is on-ground"
+    elif fs == 4:
+        text = "alert, SPI, aircraft is airborne or on-ground"
+    elif fs == 5:
+        text = "no alert, SPI, aircraft is airborne or on-ground"
 
-def id(msg):
-    '''return the squawk code (identifier)'''
-    if common.df(msg) == 5:
-        binaryraw = common.hex2bin(msg)
-        altcode = binaryraw[19:32]  # Here we could also put the common.idcode(msg).
-        return common.squawk(altcode)
-    else:
-        raise RuntimeError("Incorrect or inconsistent message types")
+    return fs, text
+
+
+@_checkdf
+def dr(msg):
+    """Decode downlink request.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: downlink request, description
+
+    """
+    msgbin = common.hex2bin(msg)
+    dr = common.bin2int(msgbin[8:13])
+
+    text = None
+
+    if dr == 0:
+        text = "no downlink request"
+    elif dr == 1:
+        text = "request to send Comm-B message"
+    elif dr == 4:
+        text = "Comm-B broadcast 1 available"
+    elif dr == 5:
+        text = "Comm-B broadcast 2 available"
+    elif dr >= 16:
+        text = "ELM downlink segments available: {}".format(dr - 15)
+
+    return dr, text
+
+
+@_checkdf
+def um(msg):
+    """Decode utility message.
+
+    Utility message contains interrogator identifier and reservation type.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: interrogator identifier code that triggered the reply, and
+        reservation type made by the interrogator
+    """
+    msgbin = common.hex2bin(msg)
+    iis = common.bin2int(msgbin[13:17])
+    ids = common.bin2int(msgbin[17:19])
+    if ids == 0:
+        ids_text = None
+    if ids == 1:
+        ids_text = "Comm-B interrogator identifier code"
+    if ids == 2:
+        ids_text = "Comm-C interrogator identifier code"
+    if ids == 3:
+        ids_text = "Comm-D interrogator identifier code"
+    return iis, ids, ids_text
+
+
+@_checkdf
+def altitude(msg):
+    """Decode altitude.
+
+    Args:
+        msg (String): 14 hexdigits string
+
+    Returns:
+        int: altitude in ft
+
+    """
+    return common.altcode(msg)
+
+
+@_checkdf
+def identity(msg):
+    """Decode squawk code.
+
+    Args:
+        msg (String): 14 hexdigits string
+
+    Returns:
+        string: squawk code
+
+    """
+    return common.idcode(msg)

From f65ffd13f75e623717011b2311ace359f4e6bf9d Mon Sep 17 00:00:00 2001
From: Junzi Sun <junzisun@gmail.com>
Date: Sat, 14 Nov 2020 22:05:48 +0100
Subject: [PATCH 7/7] add tests

---
 tests/test_allcall.py | 13 +++++++++++++
 tests/test_surv.py    | 22 ++++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 tests/test_allcall.py
 create mode 100644 tests/test_surv.py

diff --git a/tests/test_allcall.py b/tests/test_allcall.py
new file mode 100644
index 0000000..e727d4b
--- /dev/null
+++ b/tests/test_allcall.py
@@ -0,0 +1,13 @@
+from pyModeS import allcall
+
+
+def test_icao():
+    assert allcall.icao("5D484FDEA248F5") == "484FDE"
+
+
+def test_interrogator():
+    assert allcall.interrogator("5D484FDEA248F5") == 22
+
+
+def test_capability():
+    assert allcall.capability("5D484FDEA248F5")[0] == 5
diff --git a/tests/test_surv.py b/tests/test_surv.py
new file mode 100644
index 0000000..0286e27
--- /dev/null
+++ b/tests/test_surv.py
@@ -0,0 +1,22 @@
+from pyModeS import surv
+
+
+def test_fs():
+    assert surv.fs("2A00516D492B80")[0] == 2
+
+
+def test_dr():
+    assert surv.dr("2A00516D492B80")[0] == 0
+
+
+def test_um():
+    assert surv.um("200CBE4ED80137")[0] == 9
+    assert surv.um("200CBE4ED80137")[1] == 1
+
+
+def test_identity():
+    assert surv.identity("2A00516D492B80") == "0356"
+
+
+def test_altitude():
+    assert surv.altitude("20001718029FCD") == 36000