autumn: comment code

autumn/autumn.s

@@ -1,12 +1,7 @@
 ; Autumn, based on the code in Hellmood's Autumn
-
 ; by deater (Vince Weaver) <vince@deater.net>
 
-; Zero Page
+; Zero Page Addresses
-BASL		= $28
-BASH		= $29
-H2		= $2C
-;COLOR		= $30
 
 XCOORDL		= $F0
 XCOORDH		= $F1
@@ -19,155 +14,194 @@ EBP4		= $F7
 COLORL		= $F8
 COLORH		= $F9
 
-TEMP		= $FA
-TEMPY		= $FB
-FRAME		= $FC
-TEMPX		= $FD
-
-
 ; Soft Switches
 KEYPRESS= $C000
 KEYRESET= $C010
-SET_GR	= $C050 ; Enable graphics
-FULLGR	= $C052	; Full screen, no text
-PAGE0	= $C054 ; Page0
-PAGE1	= $C055 ; Page1
-LORES	= $C056	; Enable LORES graphics
 
 ; ROM routines
+; Some of these are in the Applesoft ROMs so need at least an Apple II+
+; or later to run
 
-PLOT	= $F800	; plot, horiz=y, vert=A (A trashed, XY Saved)
+TEXT	= $FB36		; Set text mode
-SETCOL	= $F864
+HGR2	= $F3D8		; Set full-screen hi-res mode using page 2 ($4000)
-TEXT	= $FB36				;; Set text mode
+			;     280x192 6-colors
-BASCALC	= $FBC1
+HPLOT0	= $F457		; Plot point, (Y,X) = Horizontal, (A=Vertical)
-SETGR	= $FB40
+HCOLOR  = $F6EC		; Set color in X, must be 0..7
-HOME	= $FC58				;; Clear the text screen
-WAIT	= $FCA8				;; delay 1/2(26+27A+5A^2) us
-HLINE	= $F819
 
-HGR2	= $F3D8
-HPLOT0	= $F457		; (Y,X) = Horizontal, (A=Vertical)
-HCOLOR  = $F6EC		; color in x, must be 0..7
 
 autumn:
 
 	;===================
-	; init screen
+	; init screen			; Instruction Length
-	jsr	HGR2				; 3
+	jsr	HGR2			; 3
-	ldx	#0
-	stx	XCOORDL
-	stx	YCOORDL
-	stx	XCOORDH
-	stx	YCOORDH
-	stx	EBP1
-	stx	EBP2
-	stx	EBP3
-	stx	EBP4
-	stx	COLORH
 
-	lda	#$4f
+	; init vars to zero.  Apple II doesn't clear RAM
-	sta	COLORL
+	; some of these might not be necessary
+	; should make this a loop
+	ldx	#0			; 2
+	stx	XCOORDL			; 2
+	stx	YCOORDL			; 2
+	stx	XCOORDH			; 2
+	stx	YCOORDH			; 2
+	stx	EBP1			; 2
+	stx	EBP2			; 2
+	stx	EBP3			; 2
+	stx	EBP4			; 2
+	stx	COLORH			; 2
+
+	; not necessary? on x86 is probably the
+	; result of the VESA BIOS call
+;	lda	#$4f
+;	sta	COLORL
 
 autumn_forever:
 
-	clc
+	; 16-bit shift of color
-	rol	COLORL		; shl %ax
+	; 2nd is a rotate as asl doesn't shift in cary
-	rol	COLORH
+	asl	COLORL			; 2	; shl %ax
+	rol	COLORH			; 2
 
-	ldx	XCOORDL
+	; put old X value to X/Y
-	ldy	XCOORDH		; save old X
+	; push/pop is 1 byte each but have to get
+	; value into accumulator first
+	ldx	XCOORDL			; 2
+	ldy	XCOORDH			; 2
 
-	sec
+	; 16-bit subtraction  x=x-y
-	lda	XCOORDL
+	; need to set carry before subtraction on 6502
-	sbc	YCOORDL		; X=X-Y
+	sec				; 1
-	sta	XCOORDL
+	lda	XCOORDL			; 2
-	lda	XCOORDH
+	sbc	YCOORDL			; 2
-	sbc	YCOORDH
+	sta	XCOORDL			; 2
-	sta	XCOORDH
+	lda	XCOORDH			; 2
+	sbc	YCOORDH			; 2
+	sta	XCOORDH			; 2
 
-	cmp	#$80
+	; 16-bit arithmatic shift right of X
-	ror	XCOORDH		; asr X
+	; 6502 has no asr instruction
-	ror	XCOORDL
+	; cmp #$80 sets carry if high bit set
+	cmp	#$80			; 2
+	ror	XCOORDH			; 2
+	ror	XCOORDL			; 2
 
-	clc
+	; 16-bit add, y=y+oldx
-	txa
+	clc				; 1
-	adc	YCOORDL		; y=y+oldx
+	txa				; 1
-	sta	YCOORDL
+	adc	YCOORDL			; 2
-	tya
+	sta	YCOORDL			; 2
-	adc	YCOORDH
+	tya				; 2
-	sta	YCOORDH
+	adc	YCOORDH			; 2
+	sta	YCOORDH			; 2
 
-	cmp	#$80
+	; 16-bit arithmatic shift right of y-coord
-	ror	YCOORDH		; asr Y
+	cmp	#$80			; 2
-	ror	YCOORDL
+	ror	YCOORDH			; 2
+	ror	YCOORDL			; 2
 
-	; 32 bit rotate of low bit of Y
+	; 32 bit rotate of low bit shifted out of Y-coordinate
-	ror	EBP1
+	ror	EBP1			; 2
-	ror	EBP2
+	ror	EBP2			; 2
-	ror	EBP3
+	ror	EBP3			; 2
-	ror	EBP4		; ror bottom bit of Y through 32 bits
+	ror	EBP4			; 2
 
-	bcs	label_11f
+	; branch if carry set
+	bcs	label_11f		; 2
 
-	clc
+	; 16-bit increment of color
-	lda	COLORL
+	; no need to clear carry as we wouldn't be
-	adc	#1
+	; here if it wasn't
-	sta	COLORL
+	inc	COLORL			; 2
-	lda	COLORH
+	bne	no_oflo			; 2
-	adc	#0
+	inc	COLORH			; 2
-	sta	COLORH
+no_oflo:
 
-	clc
+	; 16-bit add of X-coord by 0x80
-	lda	XCOORDL
+	; this keeps the drawing roughly to the 280x192 screen
-	adc	#$80
+	; carry should still be clear (inc doesn't set it)
-	sta	XCOORDL		; X+=0x80
+	lda	XCOORDL			; 2
-	lda	XCOORDH
+	adc	#$80			; 2
-	adc	#$0
+	sta	XCOORDL			; 2
-	sta	XCOORDH
+	lda	XCOORDH			; 2
+	adc	#$0			; 2
+	sta	XCOORDH			; 2
 
-	sec
+	; 16-bit negate of Y-coord
-	lda	YCOORDL
+	sec				; 1
-	eor	#$FF
+	lda	YCOORDL			; 2
-	adc	#$0		; Y=-Y
+	eor	#$FF			; 2
-	sta	YCOORDL
+	adc	#$0			; 2
-	lda	YCOORDH
+	sta	YCOORDL			; 2
-	eor	#$FF
+	lda	YCOORDH			; 2
-	adc	#$0
+	eor	#$FF			; 2
-	sta	YCOORDH
+	adc	#$0			; 2
+	sta	YCOORDH			; 2
 
 label_11f:
 
-;	lda	COLOR
+	; skipping the color manipulation done here by original
-;	and	#$fc
-;	eor	#$12
-;	sta	COLOR
 
-	lda	YCOORDH
+	; if ycoord negative, loop
-	bmi	autumn_forever		; if negative, loop
+	lda	YCOORDH			; 2
+	bmi	autumn_forever		; 2
+
+	; if top bits of xcoord, loop
+	lda	XCOORDH			; 2
+	and	#$f0			; 2
+	bne	autumn_forever		; 2
 
-	lda	XCOORDH
-	and	#$f0
-	bne	autumn_forever
 
 put_pixel:
-	lda	COLORL
+	; get color mapping
-	and	#$7
+	; using lookup table for now whil trying to find best
-	beq	black1
+	lda	COLORL			; 2
-	cmp	#$4
+	and	#$7			; 2
-	bne	not_black2
+	tay				; 1
-	lda	#$5
+	ldx	color_lookup,Y		; 3 (could be 2 if we had in zero page)
-	bne	not_black2
-black1:
-	lda	#$1
 
-not_black2:
+	; actually set the color
-	tax
+	jsr	HCOLOR			; 3
-	jsr	HCOLOR
 
-	ldx	XCOORDL
+	; set up paramaters for HPLOT call
-	ldy	XCOORDH
+	ldx	XCOORDL			; 2
-	lda	YCOORDL
+	ldy	XCOORDH			; 2
-	jsr	HPLOT0
+	lda	YCOORDL			; 2
+	jsr	HPLOT0			; 3
 
-	jmp	autumn_forever			; 3
+	lda	KEYPRESS		; 3	; see if key pressed
+;	bpl	autumn_forever			; loop if not
 
+	bmi	exit_to_prompt		; 2	; jump target too far away
+	jmp	autumn_forever		; 3	; if we get under 128 bytes
+						; can use the smaller jump
+
+exit_to_prompt:
+	jsr	TEXT			; 3	; return to text mode
+	jmp	$3D0			; 3	; return to Applesoft prompt
+
+
+; Apple II Hi-Res Colors
+;   It's all NTSC artifacting and complex
+;   There can be color-class at a 3.5 pixel level
+;   And adjacent on pixels make white, adjacent off make black
+; Simplistic summary, you can have these 8 colors (6 unique)
+;	0	= Black0
+;	1	= Green
+;	2	= Purple
+;	3	= White0
+;	4	= Black1
+;	5	= Orange
+;	6	= Blue
+;	7	= White2
+
+color_lookup:
+
+	; my default, colorful palette
+;	.byte $01,$01,$02,$03, $05,$05,$06,$07
+
+
+	; orange and gren palette
+	.byte $01,$01,$03,$05, $05,$05,$01,$07
+
+
+; "Leaves"
+;  TOP-LEFT    ??   CENTER-TOP  TOP-RIGHT        LEFT   ??   CENTER-BOTTOM    ??