How to make a hex/binary transform within item definition?

Setup, Configuration and Use Scripts & Rules
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1

How do I transform a hex strings first 7 bit to a number within an item definition?
An regex returns a string of hex values that contains the information, e.g.: (hex=BA00… > bin=1011101000000000… > first7bit=1011101 > dec=93). The goal is to have the 93 as value in the number item.

Can I use a transform script in the item definition, but how to combine regex and transform?

2

If you can code the extraction of the 1’s and 0’s from the String and convert them to a number in JavaScript then you can use the JavaScript transform. Otherwise, you cannot do it within the item definition and will have to do the above in a Rule.

3

Thank you. As a rule is more flexible then a transform I decided to write a rule. A short minimal working example looks like this:

rule "MyDecodeRule"
when
  Item MessageString changed 
then
  // MessageString = "bla bla MessageData=ba0000; bla bla"
  var MessageData = transform("REGEX", ".*MessageData=([0-9a-f.]+)?;.*", MessageString.state.toString())
  // MessageData = "ba0000"
  var StringBuilder MessageDataBin = new StringBuilder
  for (char ch: MessageData.toCharArray()) {
    var i = Integer.parseInt(ch.toString(), 16)
    var s = String.format("%4s", Integer.toBinaryString(i)).replace(' ', '0')
    MessageDataBin.append(s)
  }
  // MessageDataBin = "101110100000000000000000"
  logInfo("MyDecodeRule", "MessageData = "+MessageData+" > "+MessageDataBin)
  var MyDecodedValue = Integer.parseInt(MessageDataBin.substring(0,10), 2);
  // MyDecodedValue = "93"
  logInfo("MyDecodeRule", "MyDecodedValue = "+MyDecodedValue)
end
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