beginnings of acas

pyModeS/decoder/acas.py

@@ -3,3 +3,37 @@ Decoding Air-Air Surveillance (ACAS) DF=0/16
 
 [To be implemented]
 """
+
+from pyModeS import common
+
+
+def has_multiple_threats(msg):
+    """
+    Indicate if the ACAS is processing zero, one, or more than one threat
+    simultaneously
+    :param msg:
+    :return: boolean
+    """
+    mb = common.bin2int(msg)[32:]
+
+    mte = mb[27]
+    ara_b1 = mb[8]
+
+    if ara_b1 == 0 and mte == 0:
+        # There are no active threats
+        return False
+    elif ara_b1 == 1 and mte == 0:
+        # There is a single threat
+        return False
+    elif mte == 1:
+        # There are multiple threats
+        return True
+    else:
+        return False
+
+
+def active_resolution_advisories(msg):
+    mb = common.bin2int(msg)[32:]
+    ara_b1 = mb[8]
+    ara_b2 = mb[9]
+    ara_b1 = mb[8]