;--------------------------------------------------------------------
; GridEdit by Mark Guttenbrunner
; Version 1.00
;-----------------------------------------
; 0.01 2008-11-16  started  
; 1.00 2008-11-18  first release finished
;-----------------------------------------
; Usage: Joystick 0 to move cursor, press button to set (of grid line not set) or clear
;		 (if grid line set)
;		 Keyboard:
;			C: Clear grid
;			F: set Full grid
;			1: fill mode on/off	
;			2: grid dots on/off
;			3: change grid color
;			4: change background color
;			5: luminance on/off
;--------------------------------------------------------------------
	cpu		8048
	org		400h
;--------------------------------------------------------------------
CONST_Grid_YMax					equ		0CBh
CONST_Grid_YMin					equ 	00Bh
CONST_Grid_XMax					equ 	090h
CONST_Grid_XMin					equ		000h
CONST_Grid_YDistance 			equ 	018h
CONST_Grid_XDistance 			equ 	010h
CONST_XSpeedInc					equ 	2
CONST_YSpeedInc					equ		3
CONST_XSpeedDec					equ 	-2
CONST_YSpeedDec					equ		-3
CONST_KB_ClearGrid				equ		1
CONST_KB_SetGrid				equ		2

VDC_Control						equ		0A0h
VDC_Status						equ		0A1h
VDC_Color						equ		0A3h
VDC_Sprite0_Control				equ		000h
VDC_Sprite0_Shape				equ		080h

BIOS_Reset						equ		00F1h
BIOS_ReadJoystick				equ		038Fh
BIOS_Divide						equ		03CFh
BIOS_ReadKey					equ		00B0h
;--------------------------------------------------------------------
	jmp		start			; RESET			$400
	jmp		intr			; interrupt		$402 -> my own interrupt

start:
;---------------------------------------------------------
; system init
;---------------------------------------------------------
	en		i				; interrupts off
	sel		rb1				; everything is done in rb1, except the interrupt

	call	BIOS_Reset		; reset the O2
	call	IntRAMInit		; set all startvalues

	orl		p1,#00010100b	; init VDC Access only
	anl		p1,#11110111b

	mov		r0,#VDC_Control
	mov		a,#00000000b	; turn vdc off
	movx	@r0,a

	call	SpriteInit
	clr		a
	call	fillGrid		; init Grid (we start with empty grid)

	mov		r0,#INTRAM_Color
	mov		a,@r0
	mov		r0,#VDC_Color
	movx	@r0,a			; screen color, grid color

	mov		r0,#INTRAM_Control	; start with Control = VDC and Grid On
	mov		a,@r0
	mov		r0,#VDC_Control
	movx	@r0,a
loop
;------------------------------------------------------------
; do all the work here (get joysticks and calculate positions)
;------------------------------------------------------------
	; read keyboard outside of VBlank, we don't need to waste VBlank time for this
	orl		p1,#00011000b	; keyboard on
	anl		p1,#11111011b
	call	readKeyboard

	orl		p1,#00010100b	; vdc on, keyboard off
	anl		p1,#11110111b
;---------------------------------------------------------
; wait for VSYNC
;---------------------------------------------------------
waitForVSYNC
	jf1		VSYNC
	jmp		waitForVSYNC
VSYNC
	clr		f1

	mov		r0,#VDC_Control
	clr		a							; vdc off
	movx	@r0,a

	call	moveSprite					; move the sprite to new position, if grid intersection is reached -> set incs to zero
	call	readStick					; read the joystick

	mov		r0,#INTRAM_Keyboard
	mov		a,@r0
	xrl		a,#CONST_KB_ClearGrid		; shall the grid be cleared ?
	jnz		noClearGrid
	clr		a
	call	fillGrid
	jmp		noSetGrid
noClearGrid
	mov		a,@r0
	xrl		a,#CONST_KB_SetGrid			; shall the grid be set ?
	jnz		noSetGrid		
	mov		a,#0FFh
	call	fillGrid
noSetGrid
	mov		r0,#INTRAM_Keyboard			; reset it anyway
	clr		a
	mov		@r0,a

	mov		r0,#INTRAM_Color
	mov		a,@r0
	mov		r0,#VDC_Color
	movx	@r0,a						; screen color, grid color

	mov		r0,#INTRAM_Control
	mov		a,@r0
	mov		r0,#VDC_Control				; VDC on, Grid Fill Mode, Grid Dots
	movx	@r0,a

	jmp		loop

;--------------------------------------------------------------------
; readKeyboard: get the keyboard values and act accordingly
;--------------------------------------------------------------------
readKeyboard:
	; read keys
	call	BIOS_ReadKey			; get keyboard code
	mov		r7,a
	
	xrl		a,#27					; "F"
	jnz		notF
	mov		a,#CONST_KB_SetGrid		; set the full Grid
	mov		r0,#INTRAM_Keyboard
	mov		@r0,a

notF
	mov		a,r7	
	xrl		a,#35					; "C"
	jnz		notC
	
	mov		a,#CONST_KB_ClearGrid	; clear the Grid
	mov		r0,#INTRAM_Keyboard
	mov		@r0,a

notC
	mov		a,r7	
	xrl		a,#1					; "1"
	jnz		not1
	mov		r0,#INTRAM_Control		; Fill Mode on/off
	mov		a,@r0
	jb7		Set1
	orl		a,#10000000b
	jmp		Done1
Set1
	anl		a,#01111111b
Done1
	mov		@r0,a

not1
	mov		a,r7	
	xrl		a,#2					; "2"
	jnz		not2
	mov		r0,#INTRAM_Control		; Grid Dots on/off
	mov		a,@r0
	jb6		Set2
	orl		a,#01000000b
	jmp		Done2
Set2
	anl		a,#10111111b
Done2
	mov		@r0,a

not2
	mov		a,r7
	xrl		a,#3					; "3"
	jnz		not3

	mov		r0,#INTRAM_Color		; increase Grid Color
	mov		a,@r0
	anl		a,#11111000b			; mask out the gridcolor
	mov		r4,a					; and save it
	mov		a,@r0
	add		a,#01h					; next color
	anl		a,#00000111b			; take only the gridcolor
	orl		a,r4					; and add the original color
	mov		@r0,a					; and save it back to intram	
	
not3
	mov		a,r7
	xrl		a,#4					; "4"
	jnz		not4

	mov		r0,#INTRAM_Color		; increase Background Color
	mov		a,@r0
	anl		a,#11000111b			; mask out the bgcolor
	mov		r4,a					; and save it
	mov		a,@r0
	add		a,#00001000b			; next color
	anl		a,#00111000b			; take only the bgcolor
	orl		a,r4					; and add the original color
	mov		@r0,a					; and save it back to intram	

not4
	mov		a,r7	
	xrl		a,#5					; "5"
	jnz		not5
	mov		r0,#INTRAM_Color		; luminace bit on/off
	mov		a,@r0
	jb6		Set4
	orl		a,#01000000b
	jmp		Done4
Set4
	anl		a,#10111111b
Done4
	mov		@r0,a
	
not5
	retr

;================================================================================================================
;=														=
;= 			Page 2: Joystickroutine						=
;=														=
;================================================================================================================
	align 256
;--------------------------------------------------------------------
; read Joystick, set movement-values for increase/decrease
;--------------------------------------------------------------------
readStick:
	mov		r1,#0
	call	BIOS_ReadJoystick		; read Joystick 0

; check if movement is allowed (that is -> we are not moving already
	mov		r1,#INTRAM_SpriteIncY
	mov		a,@r1
	jnz		noMovePossible			; do we move in Y ?
	inc		r1
	mov		a,@r1
	jnz		noMovePossible			; do we move in X ?

	mov		a,r3
	xrl		a,#0FFh
	jnz		notUp
	mov		r1,#INTRAM_SpriteIncY	; Joystick up -> decrease in Y
	mov		a,#CONST_YSpeedDec
	mov		@r1,a
	jmp		noMovePossible

notUp
	mov		a,r3
	xrl		a,#001h
	jnz		notDown
	mov		r1,#INTRAM_SpriteIncY	; Joystick down -> increase in Y
	mov		a,#CONST_YSpeedInc
	mov		@r1,a
	jmp		noMovePossible
notDown
	mov		a,r2
	xrl		a,#0FFh
	jnz		notLeft
	mov		r1,#INTRAM_SpriteIncX
	mov		a,#CONST_XSpeedDec		; Joystick left -> decrease in X
	mov		@r1,a
	jmp		noMovePossible
notLeft
	mov		a,r2
	xrl		a,#001h
	jnz		noMovePossible
	mov		r1,#INTRAM_SpriteIncX	; Joystick right -> increase in X
	mov		a,#CONST_XSpeedInc
	mov		@r1,a

noMovePossible
	cpl		f0
	jf0		ButtonNotPressed		; no Button -> change spriteIncs if zero (otherwise NOT)

;------------------------------------------------------------------------------------------------
; change the current gridline if in the middle of a Girdline (X+1/2 X Distance, Y+1/2 Y Distance)
;------------------------------------------------------------------------------------------------
buttonPressed:
; Y:
	mov		r0,#VDC_Sprite0_Control				; Sprite 0 Y-Position
	movx	a,@r0
	add		a,#-(CONST_Grid_YMin+CONST_Grid_YDistance/2)		; subtract half height
	mov		r2,a
	mov		r3,#CONST_Grid_YDistance			; divide by distance
	call	BIOS_Divide
	mov		a,r5
	jnz		notOnYMiddle						; if there is a rest of division, then its not the middle

	mov		r0,#VDC_Sprite0_Control+1			; Sprite 0 X-Position
	movx	a,@r0
	swap	a
	anl		a,#00Fh
	add		a,#0E0h
	mov		r0,a

	mov		a,r4								; 0 = one rotation !
	inc		a
	mov		r4,a

	mov		a,#10000000b						; rotate to the correct bit
loopYBits
	rl		a
	djnz	r4,loopYBits
	mov		r4,a

	movx	a,@r0								; is the bit we need set ?
	anl		a,r4
	jz		setGridLineY						; if not set the bit

	mov		a,r4								; invert the bitmask for clearing
	cpl		a
	mov		r4,a

	movx	a,@r0								; get value and clear bit
	anl		a,r4
	jmp		DoneGridLineY
setGridLineY
	movx	a,@r0								; get value and set bit
	orl		a,r4
DoneGridLineY
	movx	@r0,a								; write back

notOnYMiddle
; X:
	mov		r0,#VDC_Sprite0_Control+1			; Sprite 0 X-Position
	movx	a,@r0
	mov		r4,a
	anl		a,#00Fh
	xrl		a,#CONST_Grid_XDistance/2			; middle of Gridline
	jnz		ButtonNotPressed

	mov		a,r4								; upper halfbyte is the number of byte we need
	swap	a
	anl		a,#00Fh
	add		a,#0C0h
	mov		r0,a

	mov		r1,#VDC_Sprite0_Control				; Sprite 0 Y-Position
	movx	a,@r1
	mov		r2,a
	mov		r3,#CONST_Grid_YDistance			; divide by distance
	call	BIOS_Divide

	mov		a,r4								; bit 0 = 1 rotation
	inc		a
	mov		r4,a
	xrl		a,#09h								; last line ?
	jnz		standardXLoop
	
	mov		r4,#1								; then we have to use D0-D8
	mov		a,#10h								; and need only one rotation
	add		a,r0
	mov		r0,a
	
standardXLoop
	mov		a,#10000000b						; rotate to the correct bit
loopXBits
	rl		a
	djnz	r4,loopXBits
	mov		r4,a

	movx	a,@r0								; is the bit we need set ?
	anl		a,r4
	jz		setGridLineX						; if not set it

	mov		a,r4								; invert the bitmask for clearing
	cpl		a
	mov		r4,a

	movx	a,@r0								; get value and clear bit
	anl		a,r4
	jmp		DoneGridLineX
setGridLineX
	movx	a,@r0								; get value and set bit
	orl		a,r4
DoneGridLineX
	movx	@r0,a								; write it back

ButtonNotPressed
	retr
	
;---------------------------------------------------------
; fills all the grid lines
;  a = value to fill with
;---------------------------------------------------------
fillGrid:
	mov		r7,#9						; C0 - C8
	mov		r0,#0C0h
loopGridClearH1
	movx	@r0,a
	inc		r0
	djnz	r7,loopGridClearH1

	mov		r7,#9						; D0 - D8
	mov		r0,#0D0h
loopGridClearH2
	movx	@r0,a
	inc		r0
	djnz	r7,loopGridClearH2

	mov		r7,#10						; E0 - E9
	mov		r0,#0E0h
loopGridClearV
	movx	@r0,a
	inc		r0
	djnz	r7,loopGridClearV
	retr
	
;================================================================================================================
;=	Page 3: Set up all the ram and sprite																							=
;================================================================================================================
	align	256

;-----------------------------------------------------------------------
IntRAMInit:
	mov		r0,#20h					; Copy to Intram that is free for use (from 20h)
	mov		r1,#RAMData & 0ffh
	mov		r2,#RAMDataEnd-RAMData	; all the data we defined
loopCopy
	mov		a,r1
	movp	a,@a
	mov		@r0,a
	inc		r0
	inc		r1
	djnz	r2,loopCopy
	retr

RAMData
	db		00000010b				;	$A3 Color (0-2 GridColor, 3-5 Background, 6 Luminance
	db		00101000b				;	$A0 Control (3 = Grid on, 5 = Foreground, 6=Dot, 7=Fill)
	db		0						;   Keyboard Code for setting/clearing the grid
	db		0						;	SpriteIncY
	db		0						;	SpriteIncX
RAMDataEnd

INTRAM_Color		equ 20h
INTRAM_Control		equ 21h
INTRAM_Keyboard		equ 22h
INTRAM_SpriteIncY	equ	23h
INTRAM_SpriteIncX	equ	24h

;-----------------------------------------------------------------------
; r7 = spritedata
;-----------------------------------------------------------------------
SpriteInit:
	mov		r0,#VDC_Sprite0_Control	; Sprite 0 Control
	mov		a,#CONST_Grid_YMin
	movx	@r0,a					; Y-Position
	inc		r0
	mov		a,#CONST_Grid_XMin+20h
	movx	@r0,a					; X-Position
	inc		r0
	mov		a,#00111100b
	movx	@r0,a					; double sized Sprite in white
	
	mov		r0,#VDC_Sprite0_Shape	; Sprite 0 Shape
	mov		r1,#SpriteData & 0FFh
	mov		r2,#8
SpriteShapeCopy
	mov		a,r1					; get sprite data from program memory
	movp	a,@a
	movx	@r0,a					; copy to VDC
	inc		r0
	inc		r1
	djnz	r2,SpriteShapeCopy
	retr

SpriteData
	db	00101000b					; Shape of Sprite
	db	00101000b
	db	11101110b
	db	00000000b
	db	11101110b
	db	00101000b
	db	00101000b
	db	00000000b

;--------------------------------------------------------------------------------------
; move sprite to new position and reset the increase values if intersection is reached
;--------------------------------------------------------------------------------------
moveSprite:
;------------
; Y-Position
;------------
	mov		r0,#VDC_Sprite0_Control		; get Y-Position
	movx	a,@r0
	mov		r2,a
	
	mov		r1,#INTRAM_SpriteIncY
	mov		a,@r1
	add		a,r2						; new Y-Position
	mov		r2,a

	mov		a,#-CONST_Grid_YMin			; is it lower than min ? 
	add		a,r2
	jc		notToLowY

	mov		r2,#CONST_Grid_YMin			; set it to zero
	jmp		notToHighY
notToLowY
	mov		a,#(0FFh-CONST_Grid_YMax+1)	; is it higher than max ? 
	add		a,r2
	jnc		notToHighY
	mov		r2,#CONST_Grid_YMax			; set it to max
notToHighY
	mov		a,r2
	movx	@r0,a						; write back Y-Position

	; set inc reg to zero if on intersection

	mov		r4,#((CONST_Grid_YMax-CONST_Grid_YMin) / CONST_Grid_YDistance) + 1
	mov		r3,#(CONST_Grid_YMin-CONST_Grid_YDistance) & 0FFh
IsOnXGridLoop
	mov		a,r3						
	add		a,#CONST_Grid_YDistance		; get next Y-Grid-Position
	mov		r3,a
	xrl		a,r2						; is it the current Y ?
	jz		IsOnXGridFound				; found position -> done
	djnz	r4,IsOnXGridLoop			; otherwise next
	jmp		notOnYGrid					; none found, so not on Y Grid-Position
IsOnXGridFound
	clr 	a
	mov		@r1,a						; clear Y-Add
notOnYGrid

;------------
; X-Position
;------------
	mov		r0,#VDC_Sprite0_Control+1
	movx	a,@r0
	mov		r2,a						; old X-Position
	
	mov		r1,#INTRAM_SpriteIncX
	mov		a,@r1
	add		a,r2						; new X-Position
	movx	@r0,a						; write back to Sprite 0
	mov		r2,a						; and save it for later

	mov		a,#(CONST_Grid_XMin+CONST_XSpeedDec)	; is it lower than min ? 
	xrl		a,r2
	jnz		notToLowX
	mov		r2,#CONST_Grid_XMin			; set it to zero
	jmp		notToHighX
notToLowX
	mov		a,#(0FFh-CONST_Grid_XMax+1)	; is it higher than max ? 
	add		a,r2
	jnc		notToHighX
	mov		r2,#CONST_Grid_XMax			; set it to max
notToHighX
	mov		a,r2
	movx	@r0,a						; write back X-Position

	; set inc reg to zero if on intersection
	anl		a,#0Fh
	jnz		notOnXGrid					; is it on intersection ?
	
	clr 	a							; if yes
	mov		@r1,a						; clear X-Add
notOnXGrid
	retr

;-----------------------------------------------------------------------
; my interrupt routine -> set f1
;-----------------------------------------------------------------------
intr:
	sel		rb0
	mov		r6,a								; r6 saves the accumulator

	mov		r0,#VDC_status						; clear VDC_Status Register by reading it
	movx	a,@r0

	clr		f1									; we set only the f1-flag in VBlank
	cpl		f1

	mov		a,r6								; restore accumulator
	retr
;-----------------------------------------------------------------------
	db		"Manopac 2008"
	end