GSM48: Start parsing message types

GSM48.st

@@ -14,6 +14,21 @@ Object subclass: GSM48KeySeqLuType [
             yourself
     ]
 
+    GSM48KeySeqLuType class >> length: aByteArray [
+        "We always need a byte"
+        ^ 1
+    ]
+
+    GSM48KeySeqLuType class >> parseFrom: aByteArray [
+        ^ self new
+            val: (aByteArray at: 1);
+            yourself
+    ]
+
+    val [
+        ^ val
+    ]
+
     val: aVal [
         <category: 'creation'>
         val := aVal.

Tests.st

@@ -109,6 +109,10 @@ TestCase subclass: GSM48Test [
         gsm writeOnDirect: msg.
 
         self assert: msg asByteArray = res.
+
+        self assert: (GSM48KeySeqLuType length: res) = 1.
+        gsm := GSM48KeySeqLuType parseFrom: res.
+        self assert: gsm val = 16r70.
     ]
 
     testLai [