Name:
gosub
Syntax:

GOSUB address

CALL address

Address - is a label which specifies where to gosub to.

Description:

Go to sub procedure at 'address', then 'return' at a later point. The compiler also accepts 'call' as a pseudo for 'gosub'. The gosub ('goto subprocedure') command is a 'temporary' jump to a separate section of code, from which you will later return (via the return command). Every gosub command MUST be matched by a corresponding return command. Do not confuse with the goto command which is a permanent jump to a new program location.

The table shows the maximum number of gosubs available in each microcontroller. Gosubs can normally be nested up to 8 levels deep (ie there is a 8 level stack available in the microcontroller).

  gosubs interrupt stack depth
All 'M2' parts * 255 1 8
All 'X2' parts 255 1 8
All 'X1' parts 255 1 8
All 'X' parts (obsolete) 255 1 4
All 'M' parts (obsolete) 15 1 4
All 'A' parts (obsolete) 16 0 4

* On 'parallel tasking' M2 parts each task has its own separate 8 deep stack. Sub procedures are commonly used to reduce program space usage by putting repeated sections of code in a single sub-procedure. By passing values to the sub- procedure within variables, you can repeat a section of code from multiple places within the program. See the sample below for more information.

Applies To:
All
See Also:
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    Call a gosub subroutine

    Flash an LED multiple times using a gosub subroutine

    Code Example:
    main:	let b2 = 15		; set b2 value
    	gosub flsh		; call sub-procedure
    	let b2 = 5		; set b2 value
    	gosub flsh		; call sub-procedure
    	end			; stop accidentally falling into sub
    
    flsh:	for b0 = 1 to b2	; define loop for b2 times
    	  high B.1		; switch on output 1
    	  pause 500		; wait 0.5 seconds
    	  low B.1		; switch off output 1
    	  pause 500		; wait 0.5 seconds
    	next b0			; end of loop
    	return			; return from sub-procedure
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