;;Screen print. Draws a pixel at a specified position.
;; Destroys A X Y
.proc pixel_draw; Draws a pixel at  [Y = FB , X = FC, FD].  Y = 0 - 320, X= 0 - 200
    Y_pos = $FB
    X_pos = $FCFD
    byte_to_paint = $FE
    btp_mem_pos =$494A; byte to paint memory position
    C = $7071
    B =$7273
    ;; X = X_pos (mod 8)
	LDA >X_pos ; X (mod 8)
	AND #%00000111
	TAX

	;;Store pixel in byte_to_paint
	LDA #%10000000
	INX
@shift_btp:
	DEX
	BEQ end__;X=0 end this
	CLC
	ROR A
	jmp @shift_btp
end__:
	STA byte_to_paint

	;;FIND THE POSITION IN MEMORY TO WRITE PIXEL
	;; + + + + + >  X
	;; +
	;; +
	;;\/
	;; Y
	;;

	;;pos = x_offset
	LDA #%11111000
	AND >X_pos
	STA >btp_mem_pos

	LDA <X_pos
	STA <btp_mem_pos

	;;The y_pos adds offset because chunk offsets + inside chunk offset.
	;; Adding inside chunk offset
	LDA #%00000111 ; A = y (mod 8)
	AND Y_pos ;; offset to add

	;;ading offset, same as psudocode bellow
	;;Add_16 >btp_mem_pos, <btp_mem_pos, A, #$00
	CLC ; Y = b_low
	ADC >btp_mem_pos
	STA >btp_mem_pos
	LDA #$00
	ADC <btp_mem_pos ; C =0
	STA <btp_mem_pos

	LDA #$00
	STA $4B

	;;y =8 translates to 320 bytes.
	LDA #%11111000 ; A =  y - [y (mod 8)]
	AND Y_pos
	STA >C
	STA >B
	LDA #$00
	STA <C
	STA <B

	;;We need to calculate C*40. 40 = 2*2*2*(2^2 +1)
	;; _*2^2
	mult_16 >C, <C, !
	mult_16 >C, <C, !

	;; + _*1
	Add_16 >C, <C, >B, <B, !

	;; *2*2*2
	mult_16 >C, <C, !
	mult_16 >C, <C, !
	mult_16 >C, <C, !

	Add_16 >btp_mem_pos, <btp_mem_pos, >C, <C, !

	;;add offset for where bitmap is
	Add_16 >btp_mem_pos, <btp_mem_pos, #<Bitmap, #>Bitmap, !

	;;Let draw some stuff
	LDX #$00
	LDA byte_to_paint ;; note that both bytes are used!
	ORA (>btp_mem_pos, X)
	STA (>btp_mem_pos, X)
	RTS
	.endproc