Re: A86: String Writing

To: assembly-86@lists.ticalc.org
Subject: Re: A86: String Writing
From: ComAsYuAre@aol.com
Date: Tue, 19 Oct 1999 20:34:03 EDT
Reply-To: assembly-86@lists.ticalc.org


In a message dated 10/19/99 20:30:07 Eastern Daylight Time, 
akdjr@softhome.net writes:

> i have a question.  suppose i have the following string:
>  
>  text:
>  .db "Welcome to EB"
>  
>  if i do the following:
>  
>      ld b,0
>      ld hl,text
>  start:
>      push hl
>      ld d,0
>      ld e,b
>      add hl,de
>      ld a,(hl)
>      call _putc
>      pop hl
>      push bc
>      ld b,10
>  hloop:
>      halt
>      djnz hloop
>      pop bc
>      inc b
>      ld a,b
>      cp 14
>      jp z, done
>      jp start
>  done:
>      ret
>  
>  will it output the string on the screen?  You can assume that i have 
already
>  set the curCol and curRow.  Also if it won't work, do i have the right idea
>  about it?  Basically, i want to be able to write the string out letter by
>  letter.
>  

It would be FAR more efficient to make the string null-terminated.  That way 
you can use the routine on any string, and frankly the code is smaller even 
if you're using it once.

put_string:
    ld a,(hl)
    or a
    ret z           ;return when (hl)=0
    call _putc      ;display char
    inc hl
    ld b,10
put_string_delay:
    halt                ;delay
    djnz put_string_delay
    jr put_string


and call it like this:

    ld hl,text
    call put_string
    ;...more code

text:
    .db "Welcome to EB",0


----
Jonah Cohen
<ComAsYuAre@aol.com>
http://linux.hypnotic.org/~jonah/