edit automata while paused

Code/edit.asm

@@ -1,8 +1,13 @@
 INCLUDE "hardware.inc"
+INCLUDE "utils.inc"
+
+SPRITE_ANIM_DELAY EQU 12
 	
 Section "Edit memory", HRAM
 SelectX: ds 1
 SelectY: ds 1
+SpriteAnimation: ds 1
+SpriteDelay: ds 1
 
 EXPORT InitEdit
 SECTION "Init edit", ROM0
@@ -15,23 +20,186 @@ InitEdit:
 	
 EXPORT EditOldBuffer
 SECTION "Edit old buffer", ROM0
-EditOldBuffer:	
+EditOldBuffer:
+	; check start has been pressed
 	ldh a, [JoypadDown]
-	and a, %1000
+	and a, JOYPAD_START
 	ret z
 	
-.loop
+	; wait v-blank
 	halt
+	
+	; show sprites
+	ldh a, [rLCDC]
+	or a, LCDCF_OBJON
+	ldh [rLCDC], a
+	
+	; init sprite animation
 	xor a
-	ldh a, [rIF]
+	ldh [SpriteAnimation], a
+	ld a, SPRITE_ANIM_DELAY
+	ldh [SpriteDelay], a
+	
+.loop
+	; clear interrupts
+	xor a
+	ldh [rIF], a
+
+	; compute cursor X position
+	ldh a, [SelectX]
+	sla a
+	sla a
+	add a, 8
+	ld b, a
+	
+	; compute cursor Y position
+	ldh a, [SelectY]
+	sla a
+	sla a
+	add a, 16
+	ld c, a
+	
+	; update and load sprite animation
+	ldh a, [SpriteDelay]
+	dec a
+	ldh [SpriteDelay], a
+	jr nz, .same
+	ldh a, [SpriteAnimation]
+	inc a
+	and a, 3
+	ldh [SpriteAnimation], a
+	ld a, SPRITE_ANIM_DELAY
+	ldh [SpriteDelay], a
+.same
+	ldh a, [SpriteAnimation]
+	ld d, a
+	
+	; update sprite in OAM
+	SetSprite 0, b, c, d, 0
 
 	call UpdateJoypad
+	
+	; check A button has been pressed
 	ldh a, [JoypadDown]
-	and a, %1000
-	ret nz
+	and a, JOYPAD_A
+	call nz, ToggleCell
 
-	jr .loop
+	; check start has been pressed
+	ldh a, [JoypadDown]
+	and a, JOYPAD_START
+	jr nz, .exit
 	
+	; check left direction
+	ldh a, [JoypadDown]
+	and a, JOYPAD_LEFT
+	jr z, .endLeft
+	ldh a, [SelectX]
+	and a
+	jr z, .endLeft
+	dec a
+	ldh [SelectX], a
+.endLeft
 	
+	; check up direction
+	ldh a, [JoypadDown]
+	and a, JOYPAD_UP
+	jr z, .endUp
+	ldh a, [SelectY]
+	and a
+	jr z, .endUp
+	dec a
+	ldh [SelectY], a
+.endUp
 	
-	
+	; check right direction
+	ldh a, [JoypadDown]
+	and a, JOYPAD_RIGHT
+	jr z, .endRight
+	ldh a, [SelectX]
+	cp a, 39
+	jr nc, .endRight
+	inc a
+	ldh [SelectX], a
+.endRight
+	
+	; check down direction
+	ldh a, [JoypadDown]
+	and a, JOYPAD_DOWN
+	jr z, .endDown
+	ldh a, [SelectY]
+	cp a, 35
+	jr nc, .endDown
+	inc a
+	ldh [SelectY], a
+.endDown
+	
+	; wait v-blank
+	halt	
+	
+	jp .loop
+	
+.exit
+	
+	; hide sprites
+	ldh a, [rLCDC]
+	and a, ~LCDCF_OBJON
+	ldh [rLCDC], a
+	
+	ret
+
+Section "Value to flag", ROM0, ALIGN[8]
+Flag: db 1, 2, 4, 8
+	
+	; \1: horizontal stride
+ToggleInTargetBuffer: MACRO
+	; move pointer to 2x2 cell group
+	ldh a, [SelectY]
+	sra a
+	jr z, .addX\@
+	ld c, a
+	ld de, \1
+.mul\@
+	add hl, de
+	dec c
+	jr nz, .mul\@
+.addX\@
+	xor a
+	ld d, a
+	ldh a, [SelectX]
+	sra a
+	ld e, a
+	add hl, de	
+	
+	; compute cell number in 2x2 cell group
+	ldh a, [SelectX]
+	and a, 1
+	ld b, a
+	ldh a, [SelectY]
+	and a, 1
+	sla a
+	or a, b
+	
+	; transform cell number to bit offset in 2x2 cell
+	ld d, HIGH(Flag)
+	ld e, a
+	ld a, [de]
+	ld b, a
+
+	ld a, [hl]
+	xor a, b
+	ld [hl], a
+ENDM
+
+ToggleCell:
+	ldh a, [Video]
+	ld l, a
+	ldh a, [Video + 1]
+	xor a, %100 ; change to displayed video buffer
+	ld h, a
+	ToggleInTargetBuffer 32
+	ldh a, [Progress]
+	ld l, a
+	ldh a, [Old]
+	ld h, a
+	ToggleInTargetBuffer 20
+	ret