usr/src/sys/tahoe/clock.h

/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution is only permitted until one year after the first shipment
 * of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
 * binary forms are permitted provided that: (1) source distributions retain
 * this entire copyright notice and comment, and (2) distributions including
 * binaries display the following acknowledgement:  This product includes
 * software developed by the University of California, Berkeley and its
 * contributors'' in the documentation or other materials provided with the
 * distribution and in all advertising materials mentioning features or use
 * of this software.  Neither the name of the University nor the names of
 * its contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *      @(#)clock.h     7.3 (Berkeley) 6/28/90
 */

#define SECDAY          ((unsigned)(24*60*60))          /* seconds per day */
#define SECYR           ((unsigned)(365*SECDAY))        /* per common year */

#define YRREF           1970
#define LEAPYEAR(year)  ((year)%4==0)   /* good till time becomes negative */

/*
 * Software clock is software interrupt level 8
 */
#define setsoftclock()  mtpr(SIRR, 0x8)

/*
 * To calculate value for interval timer register, we
 * use the fact that 20512 yields a 60hz clock.
 */
#define hztocount(v)    ((20512*60) / (v))