convtime.c

#include	<time.h>

/*
 *	This routine converts the date and time in CP/M-86 format
 *	to Unix style date and time - seconds since 00:00:00 Jan  1 1970
 */

#define	EPOCH	2922-1		/* difference between 1970 and 1978 - note
				   adjustment since CP/M numbers days from
				   1 and Unix numbers them from 0 */

struct tod
{
	int	days;		/* since 1 Jan 1978 */
	char	hour;		/* 2 digit BCD!! */
	char	min;		/* ditto */
	char	sec;		/* ditto */
};

frmbcd(c)
unsigned char	c;
{
	return (c & 0xF) + ((c >> 4) & 0xF) * 10;
}

time_t
convtime(tod)
struct tod *	tod;
{
	time_t	t;

	t = tod->days+EPOCH;
	t *= 24;		/* now have hours */
	t += frmbcd(tod->hour);	/* add in hours from the time */
	t *= 60;		/* now minutes */
	t += frmbcd(tod->min);	/* add minutes */
	t *= 60;		/* Seconds! */
	t += frmbcd(tod->sec);
	return t;
}