jumping out of a gosub reminder

[pedja089]

I had similar ideas, but give up on them. I use something like this:

Gosub xx : If err=1 then goto yy

XX:
if something to triger going to err sub then
err=1 ' goto in different sub after retun
else
err=0 ' return and continue normally
endif

But if you must have gosub, without return, you can look up in datasheet of PIC, POP command. It should pop up stack, and free one space.

The TOS value is pulled off the return
stack and is discarded. The TOS value
then becomes the previous value that
was pushed onto the return stack.
This instruction is provided to enable
the user to properly manage the return
stack to incorporate a software stack

If I understand POP and PUSH commands, you could do something like this

If err=1 THEN
@ POP
GOTO ErrHandler
ENDIF

[mpgmike]

Don't use both. What was printed in the above post will GOTO a new address, then erase the RETURN address. This will generate a Stack Underflow condition and the PIC will "exhibit unpredictable behavior". Just use GOTO and leave the Stack alone.

[pedja089]

But if I understand correctly he want to goto and never return.
So you need to pop stack to prevent overflow.

[mpgmike]

Then yes, POP the Stack. Not sure when such an approach might be considered good programming practice, though.

[richard]

Not sure when such an approach might be considered good programming practice

using goto to control program flow = spaghetti code [hard to unravel ,hard to modify ]

spaghetti code with stack popping to undo dead subs ?

franken code ? [as in Frankenstein ]
you would need good comments with a flow diagram and a state diagram at hand to unravel it

[pedja089]

franken code ?

Not necessarlly, Lot of hi level programing language have this already implemented. eg in .net: On Error GoTo, Try, catch, etc...
Same could be done for HW. If something external happened then you need unconditionally goto something, and start program from known place.

It is not easy to implement, by any means. But it could very useful.
What longpole001 have exactly on his mind, I can't tell...

[Art]

You could count your gosub nesting level in another variable.
Increment for every gosub, and decrement for every return.
You don’t know about PBP's own gosubs, but they are supposed to be the compiler’s problem, and aren’t your responsibility.

So you would know if the value wasn’t zero when you thought it should be.

[richard]

Not necessarlly, Lot of hi level programing language have this already implemented. eg in .net: On Error GoTo, Try, catch, etc...

hmm, in python at least a sub with a "try" still returns , even if the processing aborts and executes an "try" error routine.
i see no goto or stack popping going on.

a couple of python subs with try

def process_d(tname,q):    while exitflg==0:
        dx=ser.readline()
        try :
            rt='s'
            
            ff= string.rstrip(dx)   
            int(ff,16)   ##non hex chr will cause ValueError
            if dx[0]=='A':
                 rt='w'
            
            #print dx
            ts=str(datetime.datetime.now())[:19]
            r_x=[ts,dx,rt]
            queueLock.acquire()
            q.put(r_x)
            queueLock.release()
        except ValueError:
                #print dx
                dx=[]


def bag_reading ():
    global readings
    bag_data_time =datetime.datetime.now()
    if len(readings)>0:
         
       try:
           conn=sqlite3.connect('/media/CORSAIR/wh2.db') 
           curs=conn.cursor()
           curs.executemany("INSERT INTO log values((?),(?),(?),(?))", (readings))
           # commit the changes
           conn.commit()
           conn.close()
           print 'write ',len(readings),'  ',readings[-1][0]
           readings=[]
           bag_data_time += datetime.timedelta(minutes=5)
       except sqlite3.OperationalError as err :
           print 'db busy',err
           bag_data_time += datetime.timedelta(minutes=1)  
    return   bag_data_time