Re: A86: Line routines

To: assembly-86@lists.ticalc.org
Subject: Re: A86: Line routines
From: Joshua J Seagoe <rabidcow@juno.com>
Date: Sun, 2 May 1999 07:05:39 -0700
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-86@lists.ticalc.org
Reply-To: assembly-86@lists.ticalc.org

are the lines in a fixed location or do they move or have to be
calculated?

if they're gonna be fixed, you can do something like:
	ld hl,$fc44		;start location ($fc00 + 16*y + x/8)
	ld de,16		;bytes to next line
	ld b,21-1		;height of line (h-1)
vloop: set 6,(hl)		;pixel within byte (x%8)
	add hl,de
	djnz vloop
	set 6,(hl)		;pixel within byte
to draw a vertical line

also, do the horizontal lines start/end on a byte boundry?

starting on a byte boundry:
	ld a,$ff		;8 pixels on
	ld hl,$fc45		;starting location 
	ld b,7-1		;width-1
hloop:	ld (hl),a
	inc hl
	djnz hloop
	ld (hl),a

-josh

On Sun, 2 May 1999 01:07:17 EDT PXGray@aol.com writes:
>
>I am using the built in call _ILine to draw the lines for my program, 
>
>however, it leaves junk on the graphscreen that cannot be cleared, and 
>it 
>also shows that junk even after I clear the screen.  I need a better 
>line 
>drawing routine.  All I am doing is drawing horizontal and vertical 
>lines, 
>nothing big.  Can anyone help me?
>
>.db "Patrick Gray",0
>

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