1.2.8 Using subroutines

Procedures may be defined to act as subroutines (see chapter The PROC statement for the syntax description). They are not bound to variables in this case. The CALL statement is used to invoke a subroutine from another procedure.

Subroutines are suitable to code operations which have to be done in the same way in several procedures. A common application for this is the check of the device's reply to a command. A subroutine can read the device's reply, check if it is OK and raise a fault flag if not. After a procedure sends a command to the device, it calls the subroutine which does the check.

When using subroutines, you should notice the following:

• Subroutines may be nested, this means a subroutine may contain a CALL statement to another subroutine.
• Subroutines must be defined before they can be referenced in another procedure.
• The device driver language allows to define recursive subroutines (subroutines which call themselves). You are strongly discouraged to program recursive subroutines as a program bug in your device driver may cause infinite recursion which definitely will crash the whole MNC application!