gsm: Provide access to the cell description..

GSM48.st

@@ -291,6 +291,23 @@ GSM48SimpleData subclass: GSM48CellDescription [
     <comment: 'I represent a 10.5.2.2 Cell Description'>
     <gsmName: 'cellDescription'>
     <gsmValueLength: 2>
+
+    ncc [
+        <category: 'accessing'>
+        ^ (data first bitShift: -3) bitAnd: 2r111
+    ]
+
+    bcc [
+        <category: 'accessing'>
+        ^ (data first bitShift: -0) bitAnd: 2r111
+    ]
+
+    bcch [
+        | hi low |
+        hi := data first bitShift: -6.
+        low := data second.
+        ^ (hi bitShift: 8) bitOr: low.
+    ]
 ]
 
 GSM48SimpleData subclass: GSM48ChannelDescription [

Tests.st

@@ -435,6 +435,11 @@ TestCase subclass: GSM48Test [
         inp := #(16r06 16r2B 16rFF 16r29 16r0B 16rE3 16r29 16r00 16r00) asByteArray.
         dec := GSM48MSG decode: inp readStream.
         self assert: dec toMessage asByteArray = inp.
+
+        "Now test some decoding inside"
+        self assert: dec cellDescription bcc = 7.
+        self assert: dec cellDescription ncc = 7.
+        self assert: dec cellDescription bcch = 809.
     ]
 ]