PROGRAM BCircle

!$INCLUDE="PC.LIB"

PROCEDURE BCircle(cx%,cy%,r%)
      local f%,x%,y%,ddx%,ddy%
      f%=1-r%  y%=r%  ddy%=-2*r%
      PSET(cx%,cy%+r%,1)
      PSET(cx%,cy%-r%,1)
      PSET(cx%+r%,cy%,1)
      PSET(cx%-r%,cy%,1)
      WHILE x%<y% DO
        IF f%>=0 THEN
          y%=y%-1
          ddy%=ddy%+2
          f%=f%+ddy%
        END IF
        x%=x%+1
        ddx%=ddx%+2
        f%=f%+ddx%+1
        PSET(cx%+x%,cy%+y%,1)
        PSET(cx%-x%,cy%+y%,1)
        PSET(cx%+x%,cy%-y%,1)
        PSET(cx%-x%,cy%-y%,1)
        PSET(cx%+y%,cy%+x%,1)
        PSET(cx%-y%,cy%+x%,1)
        PSET(cx%+y%,cy%-x%,1)
        PSET(cx%-y%,cy%-x%,1)
      END WHILE
END PROCEDURE

BEGIN
      SCREEN(1)
      ! Draw circles
      BCircle(100,100,40)
      BCircle(100,100,80)
END PROGRAM