General :: Parse Substring From Barcode With Variable Digit Count

I need to identify and parse (substring) a number of digits from a barcode. The barcode digit count will vary, based on the number of details included in the barcode.

For example: the barcode for GS1 DataBar begins with a 4 digit code of 8110 identifying the code as GS1. The 5th digit then identifies the number of digits directly following which constitute the manufacturers code, which can range anywhere from 6 digits to 12 digits. I need to pull the number of digits out of the barcode based on the value of the 5th digit placeholder and pull only that many digits from the string and replace them into another field. There are potentially 70 total digits in the barcode. I have only provided the first section, which I am asking the question on.

Simply put: I need to tell the substring to identify the number to parse from digit 5, (which will have a min of 6 digits and a max of 12)

How do I pull the information out of a string to create a substring in another field by first defining the number of digits to pull out (Digits 6 to 17 min of 6 digits and a max of 12 digits) based on a value within the string (digit 5= value)

So if Digit 5 is 6 the returned value would be: Digits: 6 7 8 9 10 11 (6 6 6 6 6 6 )

If Digit 6 is 9 the returned value would be: Digits: 6 7 8 9 10 11 12 13 14 (9 9 9 9 9 9 9 9 9)

The first portion of the barcode is below: There are other pieces necessary to be pulled the same way, but from other sections, and based on yet another X desinator field (the next with a min of 1 and max of 5) I assume the pull would be similarly completed.

I don't know how to write code, I have used formulas but not this detailed or specific.

Ex: I know = Min (barcode, 5, 6) would pull the 6 digits after the 5 spot, but how do I vary the 6 (count) number in the formula?

Example below: No additional spaces, dashes, letters etc. (A's = 1-4, X = 5, M's = 6-17)

A A A A X M M M M M M M M M M M M

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17