Does CLEAR Command clear return adrress of a subroutine?

[Acetronics2]

Hi, Paul

There's also something Doable ( depends on use ...) :


A GOSUB loads an address you can choose in the stack ...

if ending the SUB with a GOTO instead of a RETURN ... This address will stay as the new "return", "retfie" ... address.

That's used with the "RESUME Label" of PbP ...

I do not think "clearing" the stack would be really useful ... as a stack containing zeros will cause the device to reset ONLY its program on the first "return or so" met ...

Alain

[sayzer]

As Alain mentioned, there are potential side effects If I start playing directly with the registers.

Instead now, I am using flags being set to zero before going to a subroutine, and set the flags if something inside the subroutine is used.

Then at the end of the subroutine(s), I am using a kind of select case with "GOTO".

This way, I don't have any "return" address to care for.


This is a little code eating though; but a lot safer.

-------------------

[skimask]

As Alain mentioned, there are potential side effects If I start playing directly with the registers.
Instead now, I am using flags being set to zero before going to a subroutine, and set the flags if something inside the subroutine is used.
Then at the end of the subroutine(s), I am using a kind of select case with "GOTO".
This way, I don't have any "return" address to care for.
This is a little code eating though; but a lot safer.
-------------------

How about something like this:

main:
code....code...code...
addrreturn = 1
goto subroutine

return1:
addrreturn = 2
goto subroutine

return2:
addrreturn = 0
goto main

subroutine:
code....code....code
branch addrreturn , [ return1 , return2, return3.................]

Set your branch return location parameter, jump to the generic subroutine, branch back to wherever it came from. No calls, no gosubs, and so on...

[paul borgmeier]

Instead now, I am using flags being set to zero before going to a subroutine, and set the flags if something inside the subroutine is used.

Then at the end of the subroutine(s), I am using a kind of select case with "GOTO".

This way, I don't have any "return" address to care for.

Hi SAYZER,

I do not get what you mean by "return" address care ... why can't you just match each "gosub" with a "return" and let PBP do the work.

[sayzer]

In the code, I jump from locations to locations really very fequently.

I am having a lot of return addresses.
_________________________________

[sayzer]

Ok, here is a simple example good enough to explain the issue.

<font color="#000000">Begin:

OK = <font color="#FF0000"><b>0


</b></font>MainMenu:
<font color="#000080"><i>'...stuff is going on here...

    </i><b>IF </b></font>OK = <font color="#FF0000"><b>1 </b></font><font color="#000080"><b>THEN GOSUB </b></font>PrintMemory


    <font color="#000080"><b>GOTO </b></font>MainMenu
    
    
PrintMemory:
    <font color="#000080"><b>IF </b></font>Memory = <font color="#FF0000"><b>0 </b></font><font color="#000080"><b>THEN </b></font>Begin
    <font color="#000080"><b>RETURN    </b>
<i>' IF this IF statement is true, then I get a useless Return address on Stack,
and I get a lot of them.
</i></font>

[skimask]

Ok, here is a simple example good enough to explain the issue.
...........

If you're careful, and I mean very, very careful, you could turn off the Stack Overflow/Underflow reset bits in the CONFIG and just not worry about the RETURN addresses...let them overflow as they will.
But again, you'd have to be very careful, especially if you nest any GOSUB's at all...so that might not work out at all.
Maybe take DT's Software Gosub example shown earlier and add your own subroutine to POP the last GOSUB address off the Software Stack.

Actually, I just looked at the code for the first time...
In the swStack.inc file, you could use this section:

'------------Pop Address from the Stack---------------------------------------
Pop:
    if StackPTR = 0 then  StackEmpty = 1  ; Update Empty status
    if StackEmpty = 0 then                ; If Stack isn't Empty
       Address = Stack[StackPTR-1]        ; Get last Address from the Stack
       StackPTR = StackPTR - 1            ; Point to Prior Stack level
       StackFull = 0                      ; 0 - Since we just removed 1
    else
       STunderflow = 1                    ; Stack was Empty on swReturn
    endif
    if StackPTR = 0 then  StackEmpty = 1  ; Update Empty status
return

You have access to the Pop subroutine.

But I'm guessing here...since I haven't used to swGosub/swReturn routines at all.........

You 'include' DT's software stack routines, your code above becomes:

Begin:
OK = 0
MainMenu:
'...stuff is going on here...
    IF OK = 1 THEN
               @ swGOSUB PrintMemory
    ENDIF
    GOTO MainMenu
PrintMemory:
    IF Memory = 0 THEN
               Gosub Pop  'regular Gosub here, generic, can be used system wide
               Goto BEGIN    'no more return address from the Gosub above
    ENDIF
    swRETURN

Again, I'm guessing...