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[unix-history] / usr / src / sys / i386 / isa / clock.c

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Added stuff to read the cmos clock on startup - Don Ahn
*
* %sccs.include.386.c%
*
*      @(#)clock.c     5.3 (Berkeley) %G%
*/

/*
* Primitive clock interrupt routines.
*/
#include "param.h"
#include "time.h"
#include "kernel.h"
#include "icu.h"
#include "isa.h"

#define DAYST 119
#define DAYEN 303

startrtclock() {

       /* initialize 8253 clock */
       outb (IO_TIMER0+3, 0x36);
       outb (IO_TIMER0, 1193182/hz);
       outb (IO_TIMER0, (1193182/hz)/256);
}

/* convert 2 digit BCD number */
bcd(i)
int i;
{
       return ((i/16)*10 + (i%16));
}

/* convert years to seconds (from 1970) */
unsigned long
ytos(y)
int y;
{
       int i;
       unsigned long ret;

       ret = 0; y = y - 70;
       for(i=0;i<y;i++) {
               if (i % 4) ret += 31536000;
               else ret += 31622400;
       }
       return ret;
}

/* convert months to seconds */
unsigned long
mtos(m,leap)
int m,leap;
{
       int i;
       unsigned long ret;

       ret = 0;
       for(i=1;i<m;i++) {
               switch(i){
               case 1: case 3: case 5: case 7: case 8: case 10: case 12:
                       ret += 2678400; break;
               case 4: case 6: case 9: case 11:
                       ret += 2592000; break;
               case 2:
                       if (leap) ret += 2505600;
                       else ret += 2419200;
               }
       }
       return ret;
}


/*
* Initialize the time of day register, based on the time base which is, e.g.
* from a filesystem.
*/
inittodr(base)
       time_t base;
{
       unsigned long sec;
       int leap,day_week,t,yd;

       sec = bcd(rtcin(9)); leap = !(sec % 4); sec += ytos(sec); /* year    */
       yd = mtos(bcd(rtcin(8)),leap); sec += yd;               /* month   */
       t = (bcd(rtcin(7))-1) * 86400; sec += t; yd += t;       /* date    */
       day_week = rtcin(6);                                    /* day     */
       sec += bcd(rtcin(4)) * 3600;                            /* hour    */
       sec += bcd(rtcin(2)) * 60;                              /* minutes */
       sec += bcd(rtcin(0));                                   /* seconds */

       /* XXX off by one? Need to calculate DST on SUNDAY */
       /* Perhaps we should have the RTC hold GMT time to save */
       /* us the bother of converting. */
       yd = yd / 86400;
       if ((yd >= DAYST) && ( yd <= DAYEN)) {
               sec -= 3600;
       }
       sec += tz.tz_minuteswest * 60;

       time.tv_sec = sec;
}

#ifdef garbage
/*
* Initialze the time of day register, based on the time base which is, e.g.
* from a filesystem.
*/
test_inittodr(base)
       time_t base;
{

       outb(IO_RTC,9); /* year    */
       printf("%d ",bcd(inb(IO_RTC+1)));
       outb(IO_RTC,8); /* month   */
       printf("%d ",bcd(inb(IO_RTC+1)));
       outb(IO_RTC,7); /* day     */
       printf("%d ",bcd(inb(IO_RTC+1)));
       outb(IO_RTC,4); /* hour    */
       printf("%d ",bcd(inb(IO_RTC+1)));
       outb(IO_RTC,2); /* minutes */
       printf("%d ",bcd(inb(IO_RTC+1)));
       outb(IO_RTC,0); /* seconds */
       printf("%d\n",bcd(inb(IO_RTC+1)));

       time.tv_sec = base;
}
#endif

/*
* retreve a value from realtime clock
*/
u_char rtcin(n) {
       u_char val;

       outb(IO_RTC,n);
       do val = inb(IO_RTC+1) ; while (val != inb(IO_RTC+1));
       return (val);
}

/*
* Restart the clock.
*/
resettodr()
{
}

enablertclock() {
       INTREN(IRQ0);
       splnone();
}