[A83] Re: Fw: GrBufCpy

[Prev][Next][Index][Thread]

[A83] Re: Fw: GrBufCpy



I compiled this code...exactly as shown (in ZDS), and I ran it using the
flash debugger. It appeared to do what I think you want it to do. 12
different columns rose up from the bottom of the screen but only the
bottom moved after that. I do have a question though...How do you have
"hlminus12" without a call? I never did that before.


fire: ld e,10101101b ;seed
 ld a,0FFh
 ld (frame),a ;n
frameloop:
 ld b,12         ;x
 ld c,63         ;y
 ld hl,plotSScreen
 inc hl
filter:
 ld a,(hl)
 call hlplus12
 add (hl)
 srl a
 call hlminus12
 cp 0
 jr z,firez
 dec a
firez: ld (hl),a
 inc hl
 djnz filter
 ld b,12
 dec c
 jr nz,filter
 ld b,12
fire_loop:
 ld a,e
 ld d,e
firelupp:add e
 add e
 ;dec d
 ;jr nz,firelupp
 inc a
 ld e,a
 ld (hl),a
 inc hl
 dec b
 jr nz,fire_loop      ;x slut?
 B_CALL GrBufCpy
 ld a,(frame)
 dec a
 ld (frame),a
 cp 0
 jr nz,frameloop
 ret
hlplus12:
	ld de,12
	add hl,de
	ret
hlminus12:
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	dec hl
	ret

frame: db 0,0,0

Thomas Lutz

Steven I.T.

-----Original Message-----
From: assembly-83-bounce@lists.ticalc.org
[mailto:assembly-83-bounce@lists.ticalc.org] On Behalf Of Jens
Bj=F6rnhager
Sent: Friday, December 14, 2001 7:06 AM
To: assembly-83@lists.ticalc.org
Subject: [A83] Fw: GrBufCpy


> GrBufCpy copies the 768 bytes from plotSScreen, the graph backup =3D
buffer,
> to the display.

Yes, that's why I'm using it.. :)

> I'm not sure what the problem with your program is, but
> it could be that GrBufCpy destroys all registers, so make sure to
> push/pop appropriately, or disable interrupts and swap with the shadow
> registers.

No, I don't have any registers worth saving when calling GrBufCpy.
And the routine works as it should.

> Alternatively, go to Home Depot and purchase a large sledgehammer.

Yes, this is very frustrating.. :P

If anyone can make out anything of it, here is the routine that screws =
=3D
up
the following routines. Think of this as a demo, where this is one in a
series of effects. This one was supposed to be a kind of fire effect:

fire: ld e,10101101b ;seed
 ld a,0FFh
 ld (frame),a ;n
frameloop:=3D20
 ld b,12         ;x
 ld c,63         ;y
 ld hl,plotSScreen
 inc hl
filter:
 ld a,(hl)
 hlplus12
 add (hl)
 srl a
 hlminus12
 cp 0
 jr z,firez
 dec a
firez: ld (hl),a
 inc hl
 djnz filter
 ld b,12
 dec c
 jr nz,filter
 ld b,12
fire_loop:
 ld a,e
 ld d,e
firelupp:add e
 add e
 ;dec d
 ;jr nz,firelupp
 inc a
 ld e,a
 ld (hl),a
 inc hl
 dec b
 jr nz,fire_loop      ;x slut?
 B_CALL GrBufCpy
 ld a,(frame)
 dec a
 ld (frame),a
 cp 0
 jr nz,frameloop
 ret

In a nutshell:
I have isolated the problem to appear after a B_CALL GrBufCpy.
This routine messes up the display for routines to come.
This must mean that B_CALL GrBufCpy messes up the
display for routines to come. The display just doesn't behave
like it should after the call. After the call it seems like I just can
write to the first byte-column of the screen. If you don't understand
my problem after this, I can make two 8xp files, one with this routine
and one without so that you can see what the difference is.

I just have no idea what is happening..

/Jens
Follow-Ups: References: