Using hslider the bmp is moving horizantally, but how can i move it in circular or semicircular motion with respect to time.

code:
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panel speed_factor
{
bmap = slider_pcx;
layer = 20;
pos_x = 10;
pos_y = 25;
hslider = 10, -12, 200, cursor_pcx, 0, 60, temp1;
flags = d3d, overlay, refresh;
}

////////////////////////////////////////////////////////////////

function init_timedemo()
{
speed_factor.visible = on;
WHILE (1)
{
IF (seconds > 0) // limit the health decrease
{

temp1 = seconds - 1 ;

}
else
{
time_txt.visible = off;
wait(3);
EXIT;
}

WAIT (1);
}

}