sprites: start adding putsprite for asteroids

interlace_demo/gr_putsprite.s

@@ -0,0 +1,80 @@
+	;=============================================
+	; put_sprite
+	;=============================================
+	; Sprite to display in INH,INL
+	; Location is SPRITE_XPOS,SPRITE_YPOS
+	; Note, only works if SPRITE_YPOS is multiple of two
+
+	; NO TRANSPARENCY
+
+	; 28+ Y*(34+17+X*(18+13) + 5
+	; 33 + Y*(51+31*X)
+
+	; so if 3*2 = 321 cycles??
+
+put_sprite:
+
+	ldy	#0		; byte 0 is xsize			; 2
+	lda	(INL),Y							; 5
+	sta	CH		; xsize is in CH			; 3
+	iny								; 2
+
+	lda	(INL),Y		; byte 1 is ysize			; 5
+	sta	CV		; ysize is in CV			; 3
+	iny								; 2
+
+	lda	SPRITE_YPOS		; make a copy of ypos			; 3
+	sta	TEMPY		; as we modify it			; 3
+								;===========
+								;	28
+put_sprite_loop:
+	sty	TEMP		; save sprite pointer			; 3
+	ldy	TEMPY							; 3
+	lda	gr_offsets,Y	; lookup low-res memory address		; 4
+	clc								; 2
+	adc	SPRITE_XPOS		; add in xpos				; 3
+	sta	OUTL		; store out low byte of addy		; 3
+	lda	gr_offsets+1,Y	; look up high byte			; 4
+	adc	DRAW_PAGE	;					; 3
+	sta	OUTH		; and store it out			; 3
+	ldy	TEMP		; restore sprite pointer		; 3
+
+				; OUTH:OUTL now points at right place
+
+	ldx	CH		; load xsize into x			; 3
+								;===========
+								;	34
+put_sprite_pixel:
+	lda	(INL),Y			; get sprite colors		; 5
+	iny				; increment sprite pointer	; 2
+
+	sty	TEMP			; save sprite pointer		; 3
+	ldy	#$0							; 2
+	sta	(OUTL),Y		; and write it out		; 6
+								;============
+								;	 18
+
+put_sprite_done_draw:
+
+	ldy	TEMP			; restore sprite pointer	; 3
+
+	inc	OUTL			; increment output pointer	; 5
+	dex				; decrement x counter		; 2
+	bne	put_sprite_pixel	; if not done, keep looping	; 3
+								;==============
+								;	13
+
+									; -1
+	inc	TEMPY			; each line has two y vars	; 5
+	inc	TEMPY							; 5
+	dec	CV			; decemenet total y count	; 5
+	bne	put_sprite_loop		; loop if not done		; 3
+								;==============
+								;	17
+
+									; -1
+	rts				; return			; 6
+
+
+
+

interlace_demo/sprites.s

@@ -23,20 +23,25 @@ BASL		= $28
 BASH		= $29
 FRAME		= $60
 BLARGH		= $69
+SPRITE_XPOS	= $E0
+SPRITE_YPOS	= $E1
 DRAW_PAGE	= $EE
 
+
 FIRE_X		= $F0
 FIRE_Y		= $F1
+YPOS		= $F2
+YADD		= $F3
+BLAST1		= $F4
+BLAST2		= $F5
+FIRE		= $F6
+TEMP		= $F7
+WHICH		= $F8
+TEMPY		= $F9
+LEVEL_DONE	= $FA
 
-YPOS		= $F3
-YADD		= $F4
-BLAST1		= $F5
-BLAST2		= $F6
-FIRE		= $F7
-TEMP		= $FA
-WHICH		= $FB
-TEMPY		= $FC
-LEVEL_DONE	= $FD
+INL		= $FC
+INH		= $FD
 OUTL		= $FE
 OUTH		= $FF
 
@@ -1013,7 +1018,7 @@ erase_fire:
 .include "gr_copy.s"
 .include "vapor_lock.s"
 .include "delay_a.s"
-
+.include "gr_putsprite.s"
 
 .assert >gr_offsets = >gr_offsets_done, error, "gr_offsets crosses page"
 .assert >wait_loop = >(wait_loop_end-1), error, "wait_loop crosses page"