;Weenie Instructions
;These weenie instructions don't even alter memory, only registers and flags.
;They are CLC, CLD, CLI, CLV, DEX, DEY, INX, INY, NOP, SEC, SED, SEI, TAX, TAY
;TSX, TXA, TXS, and TYA. They take two cycles.

;///////////////////////////////////////////////////////////////
;//	3 Bars Background Effect Demo by Christian Bogey      //
;//                  Friday, April 30, 2004                   //
;///////////////////////////////////////////////////////////////


    	processor 6502 
        include "vcs.h" 
        include "macro.h" 

	SEG CODE
	ORG $F000	; Start Adress

Start		; Standard init code

	SEI	; Clear Interrups. The 6507 doesn't use interrupts but
		; the program can run on a 7800 (6502) which use it.
		; Prevent from interferences too : interrupt capabilities
		; are included in the 6507 but the pins aren't linked.
	CLD	
	LDX #$FF
	TXS
Clear_Mem
	LDA #0
	STA 0,X
	DEX
	BNE Clear_Mem	; Clear mem countdown from $FF to $01 
			; >>>>>>>>> VBLANK Set to 0 Later

;some value
;	ldx #0
c_s:
	lda mdata,x
	sta move_data,x
	inx
	cpx #16
	bne c_s


New_Frame 
        ; Start of Vertical Sync

        LDA #2 
        STA VSYNC 	; Turn VSYNC On
            
        ; Count 3 Scanlines 

        STA WSYNC 
        STA WSYNC 
        STA WSYNC 

        LDA #0 		; 			// 2 cycles
        STA VSYNC	; Turn VSYNC Off 	// 3 cycles

  	;>>>>>>>>>>>>> Start of Vertival Blank <<<<<<<<<<<<<<<<<<<
  	; Count 37 Scanlines

	LDA  #43	;			// 2 cycles
	STA  TIM64T	;			// 4 cycles
	
	;>>>>>>>>>>>>>>>> Free space for code starts here 


	;>>>>>>>>>>>>>>>> Free space for code ends here

Wait_VBLANK_End
	LDA INTIM	;			// 4 cycles
	BPL Wait_VBLANK_End	;		// 3 cycles

	STA WSYNC	;       		// 3 cycles  Total Amount = 21 cycles
			;			2812-21 = 2791; 2791/64 = 43.60
        LDA #0 
        STA VBLANK 	; Enable TIA Output
			
	;>>>>>>>>>>>>>>>> End of Vertival Blank <<<<<<<<<<<<<<<<<<<
	
	
	;>>>>>>>>>>>>>>>> KERNAL starts here <<<<<<<<<<<<<<<<<<<<<<

;        LDX #0
        LDY #0
        STA WSYNC     	; 191 + 1 = 192 Scanlines
;        NOP		; 2 Cycles
;        JMP Loop1	; + 3 Cycles // 5 Cycles are necessary for 2nd colour
        		;            // bar alignment (Next frame build)
Loop1

		TYA
		ldx #0
		cmp $8E
		bcc pt1
		cmp $8F
		bcs pt1
		ldx #$58 ; NTSC colors
pt1
		stx $FF

		ldx #0
		cmp $86
		bcc pt
		cmp $87
		bcs pt
		ldx #$C6 ; NTSC colors
pt
		txa
		eor $FF
        STA COLUBK  ; 3



		lda #0
        STA WSYNC ; 4
        INY;DEY ; 2
        CPY #192
        BNE Loop1 ; 3

; overall 160 cycles
;2+3+24+3+20+3+2+4+2+3=66,68 horisontal blank

	LDX #0
	STX COLUBK
	
	;>>>>>>>>>>>>>>>> KERNAL ends here <<<<<<<<<<<<<<<<<<<<<<<<
	
;////////////// End Of Display ////////////////////////////////////////      	
    
	LDA #%00000010 		; Disable VIA Output
        STA VBLANK      
        
	; 30 Scanlines Overscan
	LDY #29
Loop2
	STA WSYNC
	DEY
	BNE Loop2
	STA WSYNC	; 29+1 = 30
;//////////////////////////////////////////////////
	
        ; Build New Frame 
        ldx #0
        jsr calcmove
        sta $86
        clc
        adc #$20
        sta $87

		;and #$7F
;		lda #$7F
		sta AUDF0

		;eor #$0F 
		lda #2
		sta AUDC0

		lda #4
		sta AUDV0


        ldx #8
        jsr calcmove
        sta $8E
        clc
        adc #$20
        sta $8F

       	JMP New_Frame

move_data = $80

calcmove:
	lda move_data+1,X ; hl1+1 ; lsb,msb
	cmp move_data+5,X ;#$18+4
	bcs zobra1
	lda move_data+2,X ; de1
	clc
	adc move_data+4,X ; #$20
	sta move_data+2,X ; de1
	bcc zobra0
	inc move_data+3,X ;de1+1
zobra0
	jmp zobra2
zobra1
	lda move_data+2,X ;de1
	sec
	sbc move_data+4,X ;#$20
	sta move_data+2,X ;de1

	lda move_data+3,X ;de1+1
	sbc #$00
	sta move_data+3,X ;de1+1
zobra2
	lda move_data,X ;hl1
	clc
	adc move_data+2,X ;de1
	sta move_data,X ;hl1

	lda move_data+1,X ;hl1+1
	adc move_data+3,X ;de1+1
	sta move_data+1,X ;hl1+1
; value2
	rts

mdata:
	.byte 0,0 ;hl1 0 1
	.byte 0,0 ;de1 2 3
	.byte  $26/2 ;bc 4
	.byte $58 ; for cmp 5
	.byte 0,0 ; 6 7 

	.byte 0,0 ;8 9
	.byte 0,0 ;A B
	.byte $16 ;$16 ;C
	.byte $50 ; D
	.byte 0,0 ; E F

parte:

	ORG $FFFA 

        .word Start 	; NMI - Not used by the 2600 but exists on a 7800
        .word Start     ; RESET 
        .word Start    	; IRQ - Not used by the 2600 but exists on a 7800

        END