CLK_INTERVAL
if (profint > CLK_INTERVAL)
profint = CLK_INTERVAL;
if (CLK_INTERVAL % profint != 0)
profint = CLK_INTERVAL / (CLK_INTERVAL / profint);
profscale = CLK_INTERVAL / profint;
#define CLK_INTH ((CLK_INTERVAL >> 8) & 0xff) /* high byte */
#define CLK_INTL (CLK_INTERVAL & 0xff) /* low byte */
#define PRF_INTERVAL CLK_INTERVAL
if (profint > CLK_INTERVAL || (CLK_INTERVAL % profint) != 0)
profint = CLK_INTERVAL;
profscale = CLK_INTERVAL / profint;