'This scroller is made by Markus Svilans
'email: bh447@freenet.carleton.ca
'date: September 8th, 1997
'I don't care if you give me credit or not if you use this.
'Enjoy and (ab)use at your own risk.
'ps- this is for PowerBasic

$compile exe
$optimize speed
$cpu 80286
DECLARE SUB Scroll (row%, text$, colour%)

RANDOMIZE TIMER

CLS

'scrolling$ = "Scrolling Marquee by Markus Svilans"


Scroll 8, "Scrolling Marquee by Markus Svilans", RND * 14 + 1
Scroll -2, "Clips to screen on top", rnd*14+1
Scroll 19, "and on the bottom.",rnd*14+1
Scroll 8, "Enjoy.", rnd*14+1


DEFINT A-Z
SUB Scroll (row, scrolltext AS STRING, colour)

dim absolute buffer(1999) at &hb800  'array at screen buffer for faster
                                     'printing.

DIM BitMask(0 TO 7)       'bitmasks
FOR i = 0 TO 7
	BitMask(i) = 2 ^ i
NEXT i

textlen = LEN(scrolltext$)
text$ = scrolltext$
FOR i = 1 TO textlen
	MID$(text$, i, 1) = MID$(scrolltext$, textlen - i + 1, 1)
NEXT i

DIM marquee(1 TO textlen, 7) as byte

DEF SEG = &HF000 'get characters out of memory

FOR char = 1 TO textlen  'for each character of the string
	FOR scanline = 1 TO 8   'for each scanline
		marquee(char, scanline - 1) = PEEK(&H0FA6D + (ASC(MID$(text$, char, 1)) *8) + scanline)
	NEXT scanline
NEXT char

DEF SEG

col = 80 + textlen * 8

DO
   wait &h3da,8          'delay..
   start!=timer
   do until timer-start!>=.01
   loop
	FOR i = textlen TO 1 STEP -1  'for each letter of the string
		FOR j = 0 TO 7 'for each scanline
			r = row + j
			if r >= 0 then
         	IF r > 25 THEN EXIT FOR
				c = (col - i * 8)
				IF c > 80 THEN GOTO newcol
				FOR k = 0 TO 7   'for each column
	            if c+k>=1 and c+k<=80 then   'are we still inside the
'screen limits
						IF (marquee(i, j) AND BitMask(7 - k)) THEN
						
buffer(r*80+c+k-1)=cvi(chr$(219)+chr$(colour)) 'draw dot
						ELSE
						
buffer(r*80+c+k-1)=cvi(chr$(32)+chr$(colour)) 'erase dot
	            	end if
					END IF
				NEXT k
         end if
		NEXT j
	NEXT i
newcol:
	col = col - 1
	IF col <= 0 THEN EXIT DO    'has the string scolled past edge
                                      'of screen? If so then exit sub.
   'if inkey$<>"" then end
LOOP
END SUB