A86: Will this work?

To: assembly-86@lists.ticalc.org
Subject: A86: Will this work?
From: BIOSERRORS <BIOSERRORS@aol.com>
Date: Tue, 19 May 1998 00:05:40 EDT
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org


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I'm attempting to fully grasp the concept of drawing sprites...  Will the
following code work???

PutSprite:						;8x8 sprites ONLY
;hl -> Sprite
;b = xCoord (1-16)				;Like in the OS, except max is 16, instead of 21,
;c = yCoord (1-8)				;because OS uses 8x6 sprites.
;This routine destroys all registers.
	push	hl					;Save the pointer
	dec		b					;duh		=)
	dec		c					;duh		=)
	ld		(hl),c
	add		hl,hl				;*2
	add		hl,hl				;*4
	add		hl,hl				;*8
	add		hl,hl				;*16
	add		hl,hl				;*32
	add		hl,hl				;*64
	add		hl,hl				;*128 - Skip 16 bytes for each row * 8 rows for each sprite
	push	hl					;ld	hl
	pop		de					;in de
	ld		(hl),b
	add		hl,de				;add the xCoord
	push	hl					;ld	hl
	pop		de					;in de
	ld		hl,VIDEO_MEM
	add		hl,de				;Now the sprite is aligned.  (I think)
	pop		de					;Get the pointer to the sprite
	ld		b,8					;8 bytes to be transferred
PutSpriteLoop:
	push	bc					;Save bit counter
	ld		a,(de)				;copy 1 byte from de
	ld		(hl),a				;to hl
	ld		bc,16				;Skip 16 bytes ahead
	add		hl,bc
	push	hl
	push	de
	pop		hl
	add		hl,bc
	push	hl
	pop		de
	pop		hl
	pop		bc
	djnz	PutSpriteLoop
	ret							;Return