gsm48: Decode the Request Reference IE

GSM48.st

@@ -318,6 +318,29 @@ GSM48SimpleData subclass: GSM48RequestReference [
 
     <gsmName: 'requestReference'>
     <gsmValueLength: 3>
+
+    ra [
+        <category: 'decoding'>
+        ^ data at: 1
+    ]
+
+    t1 [
+        <category: 'decoding'>
+        ^ (data at: 2) bitShift: - 3
+    ]
+
+    t2 [
+        <category: 'decoding'>
+        ^ (data at: 3) bitAnd: 2r00011111
+    ]
+
+    t3 [
+        | high low |
+        <category: 'decoding'>
+        high := (data at: 2) bitAnd: 2r111.
+        low := (data at: 3) bitShift: -5.
+        ^ low bitOr: (high bitShift: 3)
+    ]
 ]
 
 GSM48DataHolder subclass: GSM48IARestOctets [

Tests.st

@@ -298,6 +298,10 @@ TestCase subclass: GSM48Test [
                  16r2B 16r2B 16r2B 16r2B) asByteArray.
         dec := GSM48MSG decode: inp readStream.
         self assert: dec type = GSM48RRImmediateAssignCommand messageType.
+        self assert: dec requestReference ra = 16r1A.
+        self assert: dec requestReference t1 = 1.
+        self assert: dec requestReference t2 = 15.
+        self assert: dec requestReference t3 = 17.
         self assert: dec toMessage asByteArray = inp.
     ]