Re: A83: Sprite routine problem

To: <assembly-83@lists.ticalc.org>
Subject: Re: A83: Sprite routine problem
From: "Ben Wise" <bwise@labyrinth.net.au>
Date: Sun, 5 Sep 1999 14:51:19 +1000
References: <19990904220008.58CDEA404C@towerguard.unix.edu.sollentuna.se>
Reply-To: assembly-83@lists.ticalc.org


Ok - well there were a few errors in your code... See the !!!!! comments :)

Here is a version which works... Of course there are heaps of optimiztions
you could make to your routine, such as not using the ix register for the
sprite address but using the HL register (for much faster access to the
sprite data). Anyhow hope this helps. Email me if you have any questions.

Ben.

Here is a corrected version of your routine:
.NOLIST
#define equ .EQU
#define EQU .equ
#define end .end
#include "ti83asm.inc"
#include "tokens.inc"
.LIST
.org     9327h

 call _clrLCDFull
 call _grbufclr ;!!! Actually clear out the memory used for the graph
buffer. !!!
 ld b,48 ;!!!!!!!!! NOTE the change - register b now...!!!!!!!!!
 ld e,32
 ld ix,big_sprite
 call _Big_Sprite
 call _grbufcpy_v
loop:
 call _getkey
 ret
;!!! Just use ret here... what if getkey returns zero??? maybe not
possible... always better to be safe than sorry.!!!

;Input: b-x coord, e-y coord, ix-sprite address
;Output: 8x16 XOR sprite written to 8e29h
_Big_Sprite:
 ld hl,0
 ld d,0 ;!!!!!!!You just killed one of your former sprite
coordinates!!!!!!!!!
;*********Calculate addy in graphbuf********
 sla e  ;Do y*12
 sla e
 add hl,de
 add hl,de
 add hl,de
 ld e,b ;!!! note I've loaded e with b - reflecting the earlier changes.!!!
 srl e  ;Do x/8
 srl e
 srl e
 add hl,de
 ld de,8e29h
 add hl,de
 ;!!!!Fine (now) til this point.!!!!!

 ld a,b
 and 00000111b
;cp 0 ;checks if sprite is aligned !!!!! This is not needed. cp will set
zero flag if result is zero!!!!!!
 jr z,Aligned_Sprite ;If so, goto aligned sprite bit


;********Non-aligned sprite bit starts here********
  ;!!! here, a contains the number of shifts required !!!

  ld de,0

  ld b,a  ;Shift counter
  ld c,16  ;Line counter
Line_Loop:
   ld d,(ix+0)
   push bc
Shift_Loop:
   srl d
   rr e
   djnz Shift_Loop
   pop bc
   ld a,d  ;Write line to graphbuf
   xor (hl)
   ld (hl),a
   inc hl
   ld a,e
   xor (hl)
   ld (hl),a
   ld de,11d
   add hl,de
   inc ix
   dec c
  ;cp 0 ;!!! again not needed... dec will set zero flag when c reaches zero.
   jr nz,Line_Loop
   ret
  ;********Aligned sprite bit starts here********
Aligned_Sprite:
   ld c,16  ;Line counter
Aligned_Loop:
   ld d,(ix+0)
   ld a,d
   xor (hl)
   ld (hl),a
   ld de,12d
   add hl,de
   inc ix
   dec c
  ; cp 0 ; !!! no comment !!!
   jr nz,Aligned_Loop
   ret

big_sprite:
   .db 11111111b
   .db 11000011b
   .db 10100101b
   .db 10011001b
   .db 10011001b
   .db 10100101b
   .db 11000011b
   .db 10000001b
   .db 10000001b
   .db 11000011b
   .db 10100101b
   .db 10011001b
   .db 10011001b
   .db 10100101b
   .db 11000011b
   .db 11111111b
.end
END


----- Original Message -----
From: Assembly-83 Digest <owner-assembly-83@lists.ticalc.org>
To: <assembly-83-digest@lists.ticalc.org>
Sent: Sunday, 5 September 1999 8:00
Subject: Assembly-83 Digest V1 #808


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