GSM48: Add code to encode a phone number.

GSM48.st

@@ -496,11 +496,16 @@ Object subclass: GSMNumberingPlan [
 Object subclass: GSMNumberDigits [
     <comment: 'I represent table 10.5.118 continued'>
     DigitMap := nil.
+    ReverseMap := nil.
 
     GSMNumberDigits class >> mapDigit: aBinary [
         ^ self digitMap at: aBinary asInteger + 1.
     ]
 
+    GSMNumberDigits class >> digitMap: aDigit [
+        ^ self reverseMap at: aDigit.
+    ]
+
     GSMNumberDigits class >> digitMap [
         ^ DigitMap ifNil: [
             DigitMap := Dictionary new.
@@ -518,6 +523,19 @@ Object subclass: GSMNumberDigits [
         ].
     ]
 
+    GSMNumberDigits class >> reverseMap [
+        ^ ReverseMap ifNil: [
+            ReverseMap := Dictionary new.
+            self digitMap associationsDo: [:each |
+                ReverseMap at: each value put: (each key - 1).
+            ].
+
+            ReverseMap yourself.
+        ].
+    ]
+
+
+
     GSMNumberDigits class >> decodeFrom: anArray [
         | str |
 
@@ -538,6 +556,32 @@ Object subclass: GSMNumberDigits [
 
         ^ str asString
     ]
+
+    GSMNumberDigits class >> encodeFrom: aNumber [
+        | digits res |
+        digits := OrderedCollection new.
+
+        aNumber do: [:digit |
+            digits add: (self digitMap: digit).
+        ].
+
+        digits size odd
+            ifTrue: [
+                digits add: 16rF.
+        ].
+
+        "Create the binary structure"
+        res := OrderedCollection new.
+        1 to: digits size by: 2 do: [:each |
+            | low high |
+            low := digits at: each.
+            high := digits at: each + 1.
+
+            res add: (low bitOr: (high bitShift: 4)).
+        ].
+
+        ^ res asByteArray.
+    ]
 ]
 
 GSM48DataHolder subclass: GSMCalledBCDNumber [

Tests.st

@@ -207,6 +207,16 @@ TestCase subclass: GSM48Test [
         number := #(73 132 50 23 120).
         res := GSMNumberDigits decodeFrom: number.
         self assert: res = '9448237187'.
+
+        number := #(73 132 50 23 120 186 220 174).
+        res := GSMNumberDigits decodeFrom: number.
+        self assert: res = '9448237187*#abc*'.
+    ]
+
+    testNumberEncode [
+        | res |
+        res := GSMNumberDigits encodeFrom: '9448237187*#abc*'.
+        self assert: res = #(73 132 50 23 120 186 220 174) asByteArray.
     ]
 ]