Hello,

> Consider this code:
> =

> default_minutes:
>         addwf   PCL, f                          ; jump table
>         retlw   .5
>         retlw   .10
>         retlw   .15
>         retlw   .20
> =

> When it was in the beginning of my code, PCL was below 0xff, =

> it worked. When tidying my code I moved the above to the =

> bottom of the source, and the code went totally havoc. After =

> 20 minutes of debugging, I found that two lines before it, =

> PCL overflowed and turned into 0x00, making the jump-table =

> return a value which made the goto go to the beginning of the code!
> =

> It's easily solvable by moving "default_minutes" to a place =

> near the top of the source, but is there any way you can =

> solve it in other ways? I mean, since the chip (16F886) got =

> 8kb program stack, PCL must be able to keep track of all 8kb data.


With the normal way, described in all the mails here, it is working fine, a=
s long you are not crossing the 2 Kbyte border!
I have the same issue here. I did some sim-debugging and had to find out, t=
hat RETLW is not restoring PCLATH correctly after returning from the comput=
ed goto.
A normal RETURN does :-(

So, what I do is, before I am grabbing the PCLATH of the table, I save the =
original PCLATH to a register. After return, I restore PCLATH from there.


		movlw	d'0'				; Startoffset f=FCr String setzen
		movwf	toffset			; Laden von toffset

		movlw	stringdef			; default stringl=E4nge =3D 32 Zeichen in stringcounter=
 laden
		movwf	stringcnt

string11loop
		movf	PCLATH,w			; store of PCLATH
		movwf	pclath_temp
		movlw HIGH text11			; load PCLATH with hi adress of texttab
		movwf	PCLATH
		movf	toffset,w			; textoffset in w laden
		call	text11			; text abholen von toffset
		movwf	tx_temp			; restore PCLATH
		movf	pclath_temp,w
		movwf	PCLATH
		movf	tx_temp,w
		call	rs232send			; text an rs232 senden
		incf	toffset			; toffset um 1 erh=F6hen
		decfsz	stringcnt		; stringcounter um 1 veringern, solange bis counter =3D=
 0
		goto 	string11loop
		return

This code does note care about the 256 byte board, since my tables are not =
so big, but I want to move them in the second or third 2KByte page.
If the tables are bigger, this code should be extended with the 256 Byte wo=
rkaround, so that the table can be 512 Byte long.

Best Jens

-- =

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