fire: work on size-optimized version

fire/Makefile

@@ -6,9 +6,10 @@ PNG_TO_RLE = ../gr-utils/png2rle
 
 all:	fire.dsk
 
-fire.dsk:	FIRE HELLO
+fire.dsk:	FIRE FIRE_TINY HELLO
 	$(DOS33) -y fire.dsk SAVE A HELLO
 	$(DOS33) -y fire.dsk BSAVE -a 0x1000 FIRE
+	$(DOS33) -y fire.dsk BSAVE -a 0x1000 FIRE_TINY
 
 ####
 
@@ -19,6 +20,15 @@ fire.o:	fire.s gr_fast_clear.s vapor_lock.s \
 	delay_a.s
 	ca65 -o fire.o fire.s -l fire.lst
 
+####
+
+FIRE_TINY:	fire_tiny.o
+	ld65 -o FIRE_TINY fire_tiny.o -C ../linker_scripts/apple2_1000.inc
+
+fire_tiny.o:	fire_tiny.s
+	ca65 -o fire_tiny.o fire_tiny.s -l fire_tiny.lst
+
+
 
 ####
 
@@ -29,6 +39,6 @@ HELLO:  hello.bas
 #####
 
 clean:		
-		rm -f *~ *.o *.lst FIRE HELLO
+		rm -f *~ *.o *.lst FIRE FIRE_TINY HELLO
 
 

fire/fire_tiny.s

@@ -0,0 +1,178 @@
+; Lo-res fire animation, size-optimized
+
+; by deater (Vince Weaver) <vince@deater.net>
+
+; based on code described here http://fabiensanglard.net/doom_fire_psx/
+
+; 611 bytes at first
+; 601 bytes -- strip out some unused code6
+; 592 bytes -- don't init screen
+; 443 bytes -- remove more dead code
+; 206 bytes -- no need to clear screen
+; 193 bytes -- un-cycle exact the random16 code
+
+; Zero Page
+SEEDL		= $4E
+SEEDH		= $4F
+TEMP		= $FA
+TEMPY		= $FB
+
+XOR_MAGIC = $7657	; "vW"
+
+; Soft Switches
+SET_GR	= $C050 ; Enable graphics
+FULLGR	= $C052	; Full screen, no text
+LORES	= $C056	; Enable LORES graphics
+
+
+fire_demo:
+
+	; GR part
+	bit	LORES							; 4
+	bit	SET_GR							; 4
+	bit	FULLGR							; 4
+
+
+	; Setup white line on bottom
+
+	lda	#$ff
+	ldx	#39
+white_loop:
+	sta	$7d0,X			; hline 24 (46+47)
+	dex
+	bpl	white_loop
+
+
+fire_loop:
+
+	ldy	#44			; 22 * 2
+
+yloop:
+
+	lda	gr_offsets,Y
+	sta	smc2+1
+	lda	gr_offsets+1,Y
+	sta	smc2+2
+	lda	gr_offsets+2,Y
+	sta	smc1+1
+	lda	gr_offsets+3,Y
+	sta	smc1+2
+
+	sty	TEMPY
+
+	ldx	#39
+xloop:
+smc1:
+	lda	$7d0,X
+	sta	TEMP
+	and	#$f		; mask off
+	tay
+
+	jsr	random16
+	lda	SEEDL
+	and	#$1
+	beq	no_change
+
+decrement:
+	lda	color_progression,Y
+	jmp	done_change
+no_change:
+	lda	TEMP
+done_change:
+
+smc2:
+	sta	$750,X
+	dex
+	bpl	xloop
+
+	ldy	TEMPY
+
+	dey
+	dey
+	bpl	yloop
+
+
+	jmp	fire_loop
+
+
+color_progression:
+	.byte	0	; 0->0
+	.byte	$88	; 1->8
+	.byte	0	; 2->0
+	.byte	0	; 3->0
+	.byte	0	; 4->0
+	.byte	0	; 5->0
+	.byte	0	; 6->0
+	.byte	0	; 7->0
+	.byte	$55	; 8->5
+	.byte	$11	; 9->1
+	.byte	0	; 10->0
+	.byte	0	; 11->0
+	.byte	0	; 12->0
+	.byte	$99	; 13->9
+	.byte	0	; 14->0
+	.byte	$dd	; 15->13
+
+
+; 16-bit 6502 Random Number Generator
+; Linear feedback shift register PRNG by White Flame
+; http://codebase64.org/doku.php?id=base:small_fast_16-bit_prng
+
+	;=============================
+	; random16
+	;=============================
+random16:
+
+	lda	SEEDL							; 3
+	beq	low_zero	; $0000 and $8000 are special values	; 3
+								;==========
+								;	  6
+lownz:
+									; -1
+	asl	SEEDL		; Do a normal shift			; 5
+	lda	SEEDH							; 3
+	rol								; 2
+	bcs	do_eor							; 3
+	bcc	no_eor							; 3
+do_eor:
+				; high byte is in A
+	eor	#>XOR_MAGIC						; 2
+	sta	SEEDH							; 3
+	lda	SEEDL							; 3
+	eor	#<XOR_MAGIC						; 2
+	sta	SEEDL							; 3
+eor_rts:
+	rts								; 6
+
+no_eor:
+	sta	SEEDH							; 3
+	jmp	eor_rts							; 3+6
+								;===========
+								;	 20
+low_zero:
+	lda	SEEDH							; 3
+	beq	do_eor			; High byte is also zero	; 3
+					; so apply the EOR
+
+ceo:									; -1
+				; wasn't zero, check for $8000
+	asl								; 2
+	beq	no_eor			; if $00 is left after the shift; 3
+					; then it was $80
+
+		; else, do the EOR based on the carry
+cep:
+	bcc	no_eor
+	bcs	do_eor
+
+
+
+
+
+
+gr_offsets:
+	.word	$400,$480,$500,$580,$600,$680,$700,$780
+	.word	$428,$4a8,$528,$5a8,$628,$6a8,$728,$7a8
+	.word	$450,$4d0,$550,$5d0,$650,$6d0,$750,$7d0
+
+