Add length parameter to GSM7Bit decode

lib/biju/pdu.rb

@@ -31,17 +31,18 @@ module Biju
         user_data_length: string[52..53],
       }
       res[:sender_number] = string[22..(22 + res[:address_length])]
-      res[:user_data] = PDU.decode_user_data(
+      res[:user_data] = PDU.decode_user_data(string[54..-1],
-        string[54..-1], res[:data_coding_scheme])
+        encoding: res[:data_coding_scheme],
+        length: res[:user_data_length].hex)
 
       res
     end
 
-    def self.decode_user_data(message, encoding = '00')
+    def self.decode_user_data(message, encoding: '00', length: 0)
       encoding = data_coding_scheme(encoding) unless encoding.is_a?(Symbol)
 
       raise ArgumentError, "Unknown encoding" unless ENCODING.has_key?(:gsm7bit)
-      ENCODING[:gsm7bit].decode(message)
+      ENCODING[:gsm7bit].decode(message, length: length)
     end
 
     def self.data_coding_scheme(dcs)

lib/biju/pdu/gsm7bit.rb

@@ -1,4 +1,5 @@
-module Biju::PDU
+module Biju
+  module PDU
     class GSM7Bit
       BASIC_7BIT_CHARACTER_SET = [
         '@', '£', '$', '¥', 'è', 'é', 'ù', 'ì', 'ò', 'Ç', "\n", 'Ø', 'ø', "\r", 'Å', 'å',
@@ -26,7 +27,7 @@ module Biju::PDU
         0x65 => '€',
       }
 
-    def self.decode(string)
+      def self.decode(string, length: 0)
         res = ''
         next_char = 0
 
@@ -43,7 +44,7 @@ module Biju::PDU
           end
         end
 
-      res
+        res[0..(length - 1)]
       end
 
       def self.encode(string)
@@ -79,3 +80,4 @@ module Biju::PDU
       end
     end
   end
+end