Screen Boxes

' ***************************************************************
'
' "SCREEN BOXES" FOR C64 - V 1.0 (MAR 2023)
' XC=BASIC 3.1 CODE BY FELICE NARDELLA
'
' ***************************************************************

' DEFINING CONSTANTS
CONST _SCREEN_ = 1024
CONST _COLOR_ = 54272

' DEFINING VARIABLES
DIM y2 AS WORD
DIM yy AS WORD
DIM ps AS WORD
DIM cp AS WORD
DIM ix AS WORD
DIM iy AS WORD
DIM iw AS WORD
DIM ih AS WORD
DIM ic AS WORD

DIM fx AS FLOAT
DIM fy AS FLOAT
DIM fw AS FLOAT
DIM fh AS FLOAT
DIM fc AS FLOAT

' SUBROUTINE DRAWING A BOX
' x,y START POS. PLOTTING COL. AND ROW OF THE BOX
' w,h WIDTH AND HEIGHT OF THE BOX
' ch CHAR CODE (160 = REVERSED SPACE)

SUB box (x AS BYTE, y AS BYTE, w AS BYTE, h AS BYTE, ch AS BYTE, c AS BYTE)
' ROWS CYCLE
	FOR yy = y TO h-1

' CALCULATE SCREEN POS & COLOR
		ps=yy*40+x+_SCREEN_
		cp=ps+_COLOR_

' CHECK IF TRESPASSING BEYOND SCREEN MEMORY
'		IF ps+w>2023 THEN CONTINUE FOR
'		IF ps+w<1024 THEN CONTINUE FOR

' WRITES & COLORS ROWS
		MEMSET ps, w, ch
		MEMSET cp, w, c
	NEXT

END SUB

RANDOMIZE TI()

DO
' CALCULATES RANDOM VALUES FOR THE BOXES POSITION AND COLORS
	fx=RND()*40.0
	fy=RND()*25.0
	fw=40.0-RND()*fx
	fh=25.0-RND()*fy
	fc=RND()*16.0
' CONVERTS VALUES TO BYTE FORMAT
	ix=CBYTE(fx)
	iy=CBYTE(fy)
	iw=CBYTE(fw)
	ih=CBYTE(fh)
	ic=CBYTE(fc)

' CALLS BOX SUBROUTINE
	CALL box(ix,iy,iw,ih,160,ic)

' INFINITE LOOP
LOOP WHILE 1