fn: huge pain getting page flipping to work

games/sb/fn.s

@@ -11,7 +11,23 @@
 fortnight_start:
 
 	lda	#$20
-	sta	HGR_PAGE
+	sta	HGR_PAGE		; why?
+
+	lda	#$00			; will be $00/$20
+	sta	DRAW_PAGE
+
+	lda	#0
+	sta	WHICH_PAGE
+
+	; disp page1
+	; erase old page2
+	; save page2
+	; draw page2
+
+	; disp page2
+	; erase old page1
+	; save page1
+	; draw page1
 
 	jsr	hgr_make_tables
 
@@ -56,17 +72,86 @@ floppy_animation:
 
 	jsr	full_decomp
 
+	lda	#4
+	sta	SPRITE_Y
+
+	lda	#$FF
+	sta	backup_sprite1
+	sta	backup_sprite2
+
 
 reset_floppy_loop:
 	lda	#0
 	sta	XPOS
+
 floppy_loop:
+
+	;=========================
+	; switch visible page
+	;=========================
+
+	lda	WHICH_PAGE
+	tax
+	sta	PAGE1,X
+	eor	#$1
+	sta	WHICH_PAGE
+
+
+	;========================
+	; switch draw page
+	;========================
+
+	lda	DRAW_PAGE
+	eor	#$20
+	sta	DRAW_PAGE
+
+	;=======================
+	; erase sprite
+	;=======================
+
+	lda	OLDER_X
+	sta	SPRITE_X
+
+	lda	WHICH_PAGE
+;	eor	#$1
+	tax
+	lda	backup_sprites_l,X
+	sta	INL
+	lda	backup_sprites_h,X
+	sta	INH
+
+	ldy	#0
+	lda	(INL),Y
+	bmi	goog
+
+	jsr	hgr_draw_sprite
+
+goog:
+
+	lda	WHICH_PAGE
+;	eor	#$1
+	tax
+	lda	backup_sprites_l,X
+	sta	OUTL
+	lda	backup_sprites_h,X
+	sta	OUTH
+
+
+	;=======================
+	; save/draw
+	;=======================
+
 	ldx	XPOS
 
-	lda	floppy_x,X
+	lda	OLD_X
-	sta	CURSOR_X
+	sta	OLDER_X
-	lda	#4
+
-	sta	CURSOR_Y
+	lda	floppy_x,X		; save/draw offscreen
+	sta	SPRITE_X
+	sta	OLD_X
+;	lda	#4
+;	sta	SPRITE_Y
+;	sta	OLD_Y
 	lda	floppy_sprite_l,X
 	sta	INL
 	lda	floppy_sprite_h,X
@@ -81,20 +166,15 @@ floppy_loop:
 
 time_loop:
 
+	; check keypress
+
 	lda	KEYPRESS				; 4
 	bmi	done_floppy
 
 	lda	#160
 	jsr	WAIT
 
-
+	jsr	inc_frame
-;	jsr	wait_until_keypress
-
-	; see if end
-	inc	FRAME
-	bne	no_frame_oflo
-	inc	FRAMEH
-no_frame_oflo:
 
 	lda	FRAMEH
 	cmp	#3
@@ -104,21 +184,15 @@ no_frame_oflo:
 	and	#$3
 	bne	time_loop
 
-	; erase sprite
-
-	lda	#<backup_sprite
-	sta	INL
-	lda	#>backup_sprite
-	sta	INH
-	jsr	hgr_draw_sprite
-
 	; move sprite
 
 	inc	XPOS
+
 	lda	XPOS
 	cmp	#18
 	bcc	floppy_loop
-	bcs	reset_floppy_loop
+	jmp	reset_floppy_loop
+
 
 done_floppy:
 	bit	KEYRESET	; clear the keyboard buffer
@@ -175,6 +249,13 @@ wait_until_keypress:
 	bit	KEYRESET	; clear the keyboard buffer
 	rts
 
+inc_frame:
+	inc	FRAME
+	bne	no_frame_oflo
+	inc	FRAMEH
+no_frame_oflo:
+	rts
+
 	.include	"zx02_optim.s"
 
 	.include	"hgr_sprite.s"
@@ -230,3 +311,9 @@ floppy_mask_h:
 	.byte	>disk_mask1,>disk_mask0
 
 
+backup_sprites_l:
+	.byte <backup_sprite1,<backup_sprite2
+
+backup_sprites_h:
+	.byte >backup_sprite1,>backup_sprite2
+

games/sb/hgr_sprite.s

@@ -2,7 +2,7 @@
 	; hgr draw sprite (only at 7-bit boundaries)
 	;===========================================
 	; SPRITE in INL/INH
-	; Location at CURSOR_X CURSOR_Y
+	; Location at SPRITE_X SPRITE_Y
 
 	; xsize, ysize  in first two bytes
 
@@ -13,7 +13,7 @@ hgr_draw_sprite:
 	ldy	#0
 	lda	(INL),Y			; load xsize
 	clc
-	adc	CURSOR_X
+	adc	SPRITE_X
 	sta	sprite_width_end_smc+1	; self modify for end of line
 
 	iny				; load ysize
@@ -37,7 +37,7 @@ hgr_sprite_yloop:
 	lda	CURRENT_ROW		; row
 
 	clc
-	adc	CURSOR_Y		; add in cursor_y
+	adc	SPRITE_Y		; add in cursor_y
 
 	; calc GBASL/GBASH
 
@@ -50,11 +50,13 @@ hgr_sprite_yloop:
 	; eor	#$60 draws on page1
 ;hgr_sprite_page_smc:
 ;	eor	#$00
+	clc
+	adc	DRAW_PAGE
 	sta	GBASH
 ;	eor	#$60
 ;	sta	INH
 
-	ldy	CURSOR_X
+	ldy	SPRITE_X
 
 sprite_inner_loop:
 

games/sb/hgr_sprite_mask.s

@@ -2,24 +2,26 @@
 	; hgr draw sprite mask and save (only at 7-bit boundaries)
 	;===========================================
 	; SPRITE in INL/INH
-	; Location at CURSOR_X CURSOR_Y
+	; Location at SPRITE_X SPRITE_Y
 
 	; xsize, ysize  in first two bytes
 
 	; sprite AT INL/INH
 
+	; save at OUTL/OUTH
+
 hgr_draw_sprite_mask_and_save:
 
 	ldy	#0
 	lda	(INL),Y			; load xsize
-	sta	backup_sprite
+	sta	(OUTL),Y
 	clc
-	adc	CURSOR_X
+	adc	SPRITE_X
 	sta	sms_sprite_width_end_smc+1	; self modify for end of line
 
 	iny				; load ysize
 	lda	(INL),Y
-	sta	backup_sprite+1
+	sta	(OUTL),Y
 	sta	sms_sprite_ysize_smc+1	; self modify
 
 	; point smc to sprite
@@ -28,6 +30,13 @@ hgr_draw_sprite_mask_and_save:
 	lda	INH
 	sta	sms_sprite_smc1+2
 
+	; point smc to sprite
+	lda	OUTL			; 16-bit add
+	sta	backup_sprite_smc1+1
+	lda	OUTH
+	sta	backup_sprite_smc1+2
+
+
 	lda	MASKL
 	sta	sms_mask_smc1+1
 	lda	MASKH
@@ -43,31 +52,31 @@ hgr_sms_sprite_yloop:
 	lda	CURRENT_ROW		; row
 
 	clc
-	adc	CURSOR_Y		; add in cursor_y
+	adc	SPRITE_Y		; add in cursor_y
 
 	; calc GBASL/GBASH
 
 	tay				; get output ROW into GBASL/H
 	lda	hposn_low,Y
 	sta	GBASL
-;	sta	INL
 	lda	hposn_high,Y
 
-	; eor	#$00 draws on page2
+
-	; eor	#$60 draws on page1
 ;hgr_sprite_page_smc:
 ;	eor	#$00
-	sta	GBASH
-;	eor	#$60
-;	sta	INH
 
-	ldy	CURSOR_X
+	clc
+	adc	DRAW_PAGE
+	sta	GBASH
+
+	ldy	SPRITE_X
 
 sms_sprite_inner_loop:
 
 
 	lda     (GBASL),Y			; load bg
-	sta	backup_sprite,X
+backup_sprite_smc1:
+	sta	$f000,X
 sms_sprite_smc1:
         eor     $f000,X			; load sprite data
 sms_mask_smc1:
@@ -93,4 +102,5 @@ sms_sprite_ysize_smc:
 
 	rts
 
-backup_sprite = $1800
+backup_sprite1 = $1800
+backup_sprite2 = $1900

games/sb/zp.inc

@@ -154,6 +154,9 @@ D2_XSPEED	= $EB
 D1_YSPEED	= $EC
 D2_YSPEED	= $ED
 
+OLD_X		= $EC
+OLDER_X		= $ED
+
 DISP_PAGE	= $EE
 DRAW_PAGE	= $EF
 
@@ -161,8 +164,8 @@ DRAW_PAGE	= $EF
 XPOS		=	$F0
 YPOS		=	$F1
 XMAX		=	$F2
-CURSOR_X	=	$F3
+SPRITE_X	=	$F3
-CURSOR_Y	=	$F4
+SPRITE_Y	=	$F4
 HGR_PAGE	=	$F5
 CURRENT_ROW	=	$F6