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⬅️ Previous capture (2023-01-29)

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"Terry & Utahna" <tolsen64@hotmail.com> wrote in message news:<z4LY9.36828
> 
>     jsr PrintRoutine
>     asc "Hello World!",00
>     ...continue assembly code here
> 
> The print routine somehow knew to RTS to the instruction just after the 00
> termination on that string.  I think the return address was pulled from the
> stack and the "modified" return address was pushed just before the RTS...Am
> I close????

You should be able to midify this to work:


	
***************************************************************
	
SAYIT Sets the curser prints the string.
	
string must be null terminated.
	

	
msb  on
	
jsr  sayit
	
dc   i1'10,10'             ; left then top
	
dc   c'Hello World',h'00'  ; note the null end
	
msb  off
	
more code    sayit returns to more code
	

	
A/X/Y  scrambled
	
***************************************************************




SAYIT    START

TAKE     EQU   $FA             ;FA,FB
HTAB     EQU   $57B
VTAB     EQU   $FB5B
COUT     EQU   $FDED           ;CHAR OUT


         PLA                   ;GET RTN ADDRESS
         STA   RTNADD
         STA   TAKE            ;USE AS INDEX
         PLA                   ;TO DATA
         STA   RTNADD+1
         STA   TAKE+1

;    CORRECT TAKE

         LDA   TAKE
         CLC
         ADC   #1
         STA   TAKE
         LDA   TAKE+1
         ADC   #0
         STA   TAKE+1

         ldy   #0              ;set the curser
         ldx   #0              ;rtnadd  counter
         lda   (take),y
         sta   htab
         inx
         iny
         lda   (take),y
         jsr   vtab
         iny
         inx


; PRINT THE MSG


LOOP     LDA   (TAKE),Y
         BEQ   DONE
         JSR   COUT
         LDA   TAKE
         CLC
         ADC   #1
         STA   TAKE
         LDA   TAKE+1
         ADC   #0
         STA   TAKE+1
         inx
         BNE   LOOP


DONE     inx          ;set the return address
         txa
         clc
         adc   rtnadd
         sta   rtnadd
         lda   rtnadd+1
         adc   #0
         pha
         ldA   RTNADD
         PHA
         RTS

RTNADD   DS    2

         END