'===========================================================================
' Subject: SPINNING DOTS                     Date: 06-15-96 (01:37)       
' Author:  Dave Navarro, Jr.                 Code: PB                     
' Origin:  comp.lang.basic.misc            Packet: GRAPHICS.ABC
'===========================================================================
' Spinning Dots
' Adapted from original Turbo Pascal source of unknown origin
' Converted to PowerBASIC 3.2 by Dave Navarro, Jr.
' Donated to the Public Domain

$DIM ALL

DIM inPort1 AS SHARED WORD
DIM nDots AS SHARED WORD

nDots = 21

TYPE Rec
  x AS WORD
  y AS WORD
  sx AS WORD
  sy AS WORD
END TYPE

DIM dot( 0 TO nDots - 1 ) AS SHARED Rec

SUB waitRetrace()
  ! mov dx, inPort1; {find crt status REG( INPUT port #1 ) }
L1:
  ! IN al, dx;
  ! test al, 8;
  ! jnz L1; {wait FOR no v retrace}
L2:
  ! IN al, dx;
  ! test al, 8;
  ! jz L2; {wait FOR v retrace}
END SUB

%tableWriteIndex = &H3C8
%tableDataRegister = &H3C9

SUB setColor( BYVAL colr AS BYTE, BYVAL r AS BYTE, BYVAL g AS BYTE, BYVAL b AS BYTE )
  ! mov dx, %tableWriteIndex
  ! mov al, colr
  ! OUT dx, al
  ! inc dx
  ! mov al, r
  ! OUT dx, al
  ! mov al, g
  ! OUT dx, al
  ! mov al, b
  ! OUT dx, al
END SUB

'plot a pixel in mode 13h
SUB plot( BYVAL x AS WORD, BYVAL y AS WORD )
  ! mov si, y; y
  ! mov di, x; x
  ! mov ax, &HA000
  ! mov es, ax
  ! mov ax, 320
  ! mul si
  ! add di, ax
  ! mov al, es: [di]
  ! NOT al
  ! mov es: [di], al
END SUB

SUB plot4( BYVAL x AS WORD, BYVAL y AS WORD )
  DIM f AS WORD
  f = 60
  plot x + f, y
  plot 199 + f-x, 199-y
  plot 199 + f-y, x
  plot y+f, 199-x
END SUB

SUB click()
  ! mov dx, &H61
  ! IN al, dx
  ! xor al, 2
  ! OUT dx, al
END SUB

FUNCTION colorFn( BYVAL x AS WORD ) AS BYTE
  colorFn = 63 - ( ABS( 100 - x ) / 2 )
END FUNCTION

SUB moveDots()
  DIM i AS INTEGER
  FOR i = 0 TO nDots - 1
    plot4 dot(i).x, dot(i).y
    INCR dot(i).x, dot(i).sx
    INCR dot(i).y, dot(i).sy
    IF dot(i).x > 200 THEN
      dot(i).sx = -dot(i).sx
      INCR dot(i).x, dot(i).sx
      click
    END IF
    IF dot(i).y > 199 THEN
      dot(i).sy = -dot(i).sy
      INCR dot(i).y, dot(i).sy
      click
    END IF
    plot4 dot(i).x, dot(i).y
  NEXT
  waitRetrace
  waitRetrace
  waitRetrace
  setcolor 255, colorFn( dot(0).x ), colorFn( dot(3).x ), colorFn( dot(6).x )
END SUB

SUB drawdots()
  DIM i AS INTEGER
  FOR i = 0 TO nDots - 1
    plot4 dot(i).x, dot(i).y
  NEXT
END SUB

SUB initDots()
  DIM i AS INTEGER, j AS WORD, K AS WORD
  j = 1
  k = 1
  FOR i = 0 TO nDots - 1
    dot(i).x  = 100
    dot(i).y  = 99
    dot(i).sx = j
    dot(i).sy = k
    INCR j
    IF j > = k THEN
      j = 1
      INCR k
    END IF
  NEXT
END SUB

FUNCTION readKey() AS STRING
  readKey = INKEY$
END FUNCTION

FUNCTION keyPressed() AS WORD
  keyPressed = INSTAT < > 0
END FUNCTION

    DEF SEG = &H40
    inPort1 = PEEKI( &H63 ) + 6
    DEF SEG
    OUT &H61, INP( &H61 ) AND ( NOT 1 )
    setcolor 255, 60, 60, 63
    initDots
ASM mov ax, &H13;
ASM INT &H10;
    drawDots
    DO
      moveDots
    LOOP UNTIL keyPressed
    ReadKey
    drawDots
ASM mov ax, 3
ASM INT &H10
END