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clock.c revision 1.1 
      1 /*	$NetBSD: clock.c,v 1.1 1995/07/25 23:12:28 chuck Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  * Copyright (c) 1994 Gordon W. Ross
      7  * Copyright (c) 1993 Adam Glass
      8  *
      9  * This software was developed by the Computer Systems Engineering group
     10  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
     11  * contributed to Berkeley.
     12  *
     13  * All advertising materials mentioning features or use of this software
     14  * must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Lawrence Berkeley Laboratory.
     17  *
     18  * Redistribution and use in source and binary forms, with or without
     19  * modification, are permitted provided that the following conditions
     20  * are met:
     21  * 1. Redistributions of source code must retain the above copyright
     22  *    notice, this list of conditions and the following disclaimer.
     23  * 2. Redistributions in binary form must reproduce the above copyright
     24  *    notice, this list of conditions and the following disclaimer in the
     25  *    documentation and/or other materials provided with the distribution.
     26  * 3. All advertising materials mentioning features or use of this software
     27  *    must display the following acknowledgement:
     28  *	This product includes software developed by the University of
     29  *	California, Berkeley and its contributors.
     30  * 4. Neither the name of the University nor the names of its contributors
     31  *    may be used to endorse or promote products derived from this software
     32  *    without specific prior written permission.
     33  *
     34  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     35  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     36  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     37  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     38  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     39  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     40  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     41  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     42  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     43  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     44  * SUCH DAMAGE.
     45  *
     46  *	@(#)clock.c	8.1 (Berkeley) 6/11/93
     47  */
     48 
     49 /*
     50  * Clock driver.
     51  */
     52 
     53 #include "sboot.h"
     54 #include "clockreg.h"
     55 static struct clockreg *clockreg = (struct clockreg *) CLOCK_ADDR;
     56 
     57 /*
     58  * BCD to decimal and decimal to BCD.
     59  */
     60 #define	FROMBCD(x)	(((x) >> 4) * 10 + ((x) & 0xf))
     61 #define	TOBCD(x)	(((x) / 10 * 16) + ((x) % 10))
     62 
     63 #define	SECDAY		(24 * 60 * 60)
     64 #define	SECYR		(SECDAY * 365)
     65 #define	LEAPYEAR(y)	(((y) & 3) == 0)
     66 
     67 /*
     68  * This code is defunct after 2068.
     69  * Will Unix still be here then??
     70  */
     71 const short dayyr[12] =
     72     { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
     73 
     74 static u_long chiptotime(sec, min, hour, day, mon, year)
     75 	register int sec, min, hour, day, mon, year;
     76 {
     77 	register int days, yr;
     78 
     79 	sec = FROMBCD(sec);
     80 	min = FROMBCD(min);
     81 	hour = FROMBCD(hour);
     82 	day = FROMBCD(day);
     83 	mon = FROMBCD(mon);
     84 	year = FROMBCD(year) + YEAR0;
     85 	if (year < 70) year = 70;
     86 
     87 	/* simple sanity checks */
     88 	if (year < 70 || mon < 1 || mon > 12 || day < 1 || day > 31)
     89 		return (0);
     90 	days = 0;
     91 	for (yr = 70; yr < year; yr++)
     92 		days += LEAPYEAR(yr) ? 366 : 365;
     93 	days += dayyr[mon - 1] + day - 1;
     94 	if (LEAPYEAR(yr) && mon > 2)
     95 		days++;
     96 	/* now have days since Jan 1, 1970; the rest is easy... */
     97 	return (days * SECDAY + hour * 3600 + min * 60 + sec);
     98 }
     99 
    100 /*
    101  * Set up the system's time, given a `reasonable' time value.
    102  */
    103 u_long time()
    104 {
    105 	register struct clockreg *cl = clockreg;
    106 	int sec, min, hour, day, mon, year;
    107 
    108 	cl->cl_csr |= CLK_READ;		/* enable read (stop time) */
    109 	sec = cl->cl_sec;
    110 	min = cl->cl_min;
    111 	hour = cl->cl_hour;
    112 	day = cl->cl_mday;
    113 	mon = cl->cl_month;
    114 	year = cl->cl_year;
    115 	cl->cl_csr &= ~CLK_READ;	/* time wears on */
    116 	return(chiptotime(sec, min, hour, day, mon, year));
    117 }
    118