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/*
* Time functions for standalone mode, on the first call to time() it tries
* to query the RTC, on success it sets it's own day counter an the PC's
* ticks since midnight clock. From the second call on it uses the day
* counter and ticks clock.
*
* NOTES:
* DOS's midnight bug is here too, it's actually in the bios.
* If there's no RTC the clock will fall to Jan 3 1970.
*/
#include <time.h>
static int mdays[13] = { 0,31,31+28,31+28+31,31+28+31+30,
31+28+31+30+31,31+28+31+30+31+30,31+28+31+30+31+30+31,
31+28+31+30+31+30+31+31,31+28+31+30+31+30+31+31+30,
31+28+31+30+31+30+31+31+30+31,31+28+31+30+31+30+31+31+30+31+30,
365 };
#define SECSPERHOUR (60*60)
#define SECSPERDAY (SECSPERHOUR*24L)
/****************************************
* Return the number of seconds that have elapsed since the start
* of 1970.
* Input:
* timer pointer to where to store result (or NULL)
* Output:
* *timer = result (unless timer == NULL)
* Returns:
* time
*/
static int xt_days = 0, ax_val, huns = 0;
static long get_time(ah)
{
#asm
#if !__FIRST_ARG_IN_AX__
mov bx,sp
mov ax,[bx+2]
#endif
mov ah,al
int $1A
jnc intok
mov cx,#-1
mov dx,cx
intok:
mov [_ax_val],ax
mov ax,dx
mov dx,cx
#endasm
}
static int
unbcd(bcdval)
int bcdval;
{
return (bcdval&0xF) + 10*((bcdval>>4)&0xF);
}
time_t time(timer)
time_t *timer;
{
unsigned day,month,year;
long rv;
time_t t;
if( xt_days ) goto XT_time;
rv = get_time(0x02);
if(rv == -1) goto XT_time;
huns = unbcd(rv & 0xFF); /* Save for stime */
rv >>= 8; t = unbcd(rv & 0xFF);
rv >>= 8; t += unbcd(rv & 0xFF)*60;
rv >>= 8; t += unbcd(rv & 0xFF)*3600;
rv = get_time(0x04);
if(rv == -1) goto XT_time;
day = unbcd(rv & 0xFF);
rv >>= 8; month = unbcd(rv & 0xFF) -1;
rv >>= 8; year = unbcd(rv & 0xFF);
rv >>= 8; year += unbcd(rv & 0xFF)*100;
year -= 1970;
if( year < 1950 && year >= 1900 )
year += 100; /* Century is not updated on RTC */
if (month <= 1 || year & 3) /* if before Feb or not a leap year */
day--; /* don't add day for leap year */
day += mdays[month]; /* day in year */
day += (year + 3) >> 2; /* add a day for each leap year */
t += ((year * 365L) + day) * SECSPERDAY;
stime(t);
if(0)
{
XT_time:
rv = get_time(0);
xt_days += (ax_val&0xFF);
rv = xt_days*SECSPERDAY + rv * 1080 / 19663;
}
if (timer)
*timer = t;
return t;
}
static long ticks;
stime(timer)
time_t timer;
{
xt_days = (timer/SECSPERDAY);
ticks = ((timer%SECSPERDAY) * 19663L + huns*196) / 1080;
huns = 0;
#asm
mov cx,[_ticks+2]
mov dx,[_ticks]
mov ah,#1
int $1A
#endasm
return 0;
}
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