PutSprite Help

To: CALC-TI@LISTS.PPP.TI.COM
Subject: PutSprite Help
From: Jim Ruble <ruble@ISERV.NET>
Date: Fri, 7 Nov 1997 14:10:42 -0500
Organization: Grand Valley State University
Reply-To: Jim Ruble <ruble@ISERV.NET>
Xref: paladin.american.edu bit.listserv.calc-ti:18546

I'm a beginner when it comes to assembly programming (although I am not
a beginner when it comes to programming in general) and I'm having a
little bit of trouble with the following code.  It assembles alright but
when I try running it garbage fills the screen.  Other than that the
program seems to be running fine (it exits when the Exit key is
pressed).  I am using USGARD 1.5.

#include "usgard.h"

.org 0
.db "Graphics Test",0

 ld a,4
 out (5),a

 call CLEARLCD
 ld b,$01
 ld c,$01
 ld hl,Block
 call &PutSprite
Loop:
 call GET_KEY
 cp $37                       ; Exit key
 jr nz, Loop
 ret

PutSprite:                  ; PutSprite routine by Jimmy Merdell
 push bc                    ; Puts sprite stored at (HL) at B,C
 push de
 ld a,63
 sub c
 ld c,a
 push hl
 push hl
 call FIND_PIXEL
 ld de,VIDEO_MEM
 add hl,de
 ex de,hl
 pop hl
 ld b,(hl)
 inc hl
 ld c,(hl)
 inc hl
 push hl
 pop ix
 ex de,hl
PS_NewRow:
 push bc
 ld d,(ix)
 inc ix
 push af
 push hl
PS_NewCol:
 rl d
 ld e,a
 jr nc,PS_NoPixel
 or (hl)
 ld (hl),a
 jr PS_NextPixel
PS_NoPixel:
 cpl
 and (hl)
 ld (hl),a
PS_NextPixel:
 ld a,e
 rrca
 jr nc,PS_SameByte
 inc hl
PS_SameByte:
 djnz PS_NewCol
 pop hl
 pop af
 ld de,16
 add hl,de
 pop bc
 dec c
 jr nz,PS_NewRow
 pop hl
 pop de
 pop bc
 ret

Block:
.db 8,8
.db %00111100
.db %01111110
.db %11111111
.db %11111111
.db %11111111
.db %11111111
.db %01111110
.db %00111100

.end


Any help would be GREATLY appreciated.  Thanks!

 - Jim

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