lemm: erase background

games/lemm/draw_lemming.s

@@ -1,8 +1,29 @@
 
+erase_lemming:
+	ldy	#0
+
+	lda	lemming_out,Y
+	beq	done_erase_lemming
+
+	lda	lemming_y,Y
+	sta	SAVED_Y1
+	clc
+	adc	#8
+	sta	SAVED_Y2
+
+	lda	lemming_x,Y
+	tax
+	inx
+	jsr	hgr_partial_restore
+
+done_erase_lemming:
+	rts
+
 
 draw_lemming:
+	ldy	#0
 
-	lda	lemming_out
+	lda	lemming_out,Y
 	beq	done_draw_lemming
 
 	lda	#<lemming_fall1_sprite
@@ -10,9 +31,9 @@ draw_lemming:
 	lda	#>lemming_fall1_sprite
 	sta	INH
 
-	ldx	lemming_x
+	ldx	lemming_x,Y
         stx     XPOS
-	lda	lemming_y
+	lda	lemming_y,Y
 	sta	YPOS
 
 	jsr	hgr_draw_sprite

games/lemm/hgr_partial_save.s

@@ -0,0 +1,45 @@
+	;=======================
+	; HGR Partial Restore
+	;=======================
+	; loads from $40 (page2)
+	; save to $20    (page1)
+
+	; restores from X = A<=to<=X
+	;               Y = SAVED_Y1 to SAVED_Y2
+
+hgr_partial_restore:
+	sta	partial_restore_x1_smc+1
+	stx	partial_restore_x2_smc+1
+
+	ldx	SAVED_Y2
+
+partial_restore_yloop:
+
+	lda	hposn_low,X
+	sta	prx_smc2+1
+	sta	prx_smc1+1
+
+	lda	hposn_high,X
+	sta	prx_smc2+2
+	clc
+	adc	#$20
+	sta	prx_smc1+2
+
+partial_restore_x2_smc:
+	ldy	#$27
+partial_restore_xloop:
+prx_smc1:
+	lda	$d000,Y
+
+prx_smc2:
+	sta	$d000,Y
+	dey
+partial_restore_x1_smc:
+	cpy	#$00
+	bpl	partial_restore_xloop
+
+	dex
+	cpx	SAVED_Y1
+	bcs	partial_restore_yloop	; bge
+
+	rts

games/lemm/lemm.s

@@ -357,6 +357,8 @@ done_release_lemmings:
 	sta	TIMER_COUNT
 timer_not_yet:
 
+	jsr	erase_lemming
+
 	jsr	move_lemmings
 
 	jsr	draw_lemming
@@ -439,6 +441,8 @@ load_song_chunk_good:
 ;	.include	"print_help.s"
 	.include	"gr_fast_clear.s"
 
+	.include	"hgr_partial_save.s"
+
 	.include	"move_lemming.s"
 	.include	"draw_lemming.s"
 

games/lemm/move_lemming.s

@@ -16,34 +16,26 @@ move_lemmings:
 do_lemming_falling:
 	inc	lemming_y
 
-	lda	lemming_y
-	clc
-	adc	#9
-	tay
-
-	lda     hposn_high,Y
-        sta     GBASH
-        lda     hposn_low,Y
-        sta     GBASL
-
-	ldy	lemming_x
-	lda	(GBASL),Y
-	and	#$7f
-	beq	done_move_lemming
-
-	lda	#LEMMING_WALKING
-	sta	lemming_status
+	jsr	collision_check_ground
 
 	jmp	done_move_lemming
 
-
 do_lemming_walking:
+	clc
+	lda	lemming_x
+	adc	lemming_direction
+	sta	lemming_x
+
+	jsr	collision_check_ground
 
 do_lemming_digging:
 
 done_move_lemming:
 	rts
 
+lemming_direction:
+	.byte 1
+
 lemming_x:
 	.byte 12
 lemming_y:
@@ -62,3 +54,29 @@ lemming_status:
 
 lemming_job:
 	.byte $00
+
+
+collision_check_ground:
+	lda	lemming_y
+	clc
+	adc	#9
+	tay
+
+	lda     hposn_high,Y
+        sta     GBASH
+        lda     hposn_low,Y
+        sta     GBASL
+
+	ldy	lemming_x
+	lda	(GBASL),Y
+	and	#$7f
+	beq	ground_falling
+ground_walking:
+	lda	#LEMMING_WALKING
+	jmp	done_check_ground
+ground_falling:
+	lda	#LEMMING_FALLING
+done_check_ground:
+	sta	lemming_status
+
+	rts

games/lemm/zp.inc

@@ -63,6 +63,8 @@ OVER_LEMMING		= $80
 TIMER_COUNT		= $81
 UPDATE_POINTER		= $82
 LEMMINGS_TO_RELEASE	= $83
+SAVED_Y1		= $84
+SAVED_Y2		= $85
 
 APPLEII_MODEL		= $8B