/*	date.cpm	Date/Time support for CP/M-80 v 3.0

	Copyright (C) 1985 Mark E. Mallett

	Permission is hereby granted to distribute this file indiscriminately.

Edit history

When	Who	What
------	---	--------------------------------
84xxxx	MEM	Create file.


	Included are

		curdtm		Get current date/time
		cvedid		Convert external to internal date
		cvided		Convert internal to external date

*/

#include	"stdio.h"
#include	"mem.h"			/* Get my standard defs */
#include	"cpm.h"			/* Get CP/M call definitions */

/* Local definitions */

typedef					/* date/time structure */
  struct
    {
    int		DAT_DAT;		/* Days since Jan 1 1978 */
    BYTE	DAT_HRS;		/* BCD hours */
    BYTE	DAT_MIN;		/* BCD minutes */
    }
  DAT;					/* Date */

/* External variables */


/* External routines */



/* Locals */


static	int mdtbl[] = {31,28,31,30,31,30,31,31,30,31,30,31};
					/* Days in each month */
/*

*//* curdtm (id, it)

	Get date/time from operating system

Accepts :

	id		Address of where to store the date in internal form
	it		Address of where to store the time in internal form

Returns :

	*id		Date as an int.
	*it		Time as an int.

*/


curdtm (id, it)

int		*id;			/* Address of date variable */
int		*it;			/* Address of time variable */

{
IND	DAT	date;			/* Date value */
IND	int	i;			/* Scratch */

CPM (_MRGDT, &date);			/* Call system to get date */
*id = date.DAT_DAT;			/* Get days since Jan 1 1978 */

i = (date.DAT_HRS>>4)&0x0F;
i = i*10 + (date.DAT_HRS&0x0F);
i = i*6 + ((date.DAT_MIN>>4)&0x0F);
i = i*10 + (date.DAT_MIN&0x0F);
*it = i;				/* Return the time. */
}
/*

*//* cvedid (id, it, m, d, y, hh, mm)

	Convert external date/time to internal date/time


Accepts :

	id		Address of internal date variable (int)
	it		Address of internal time variable (int)
	m		Month number (1-12)
	d		Day number (1-31)
	y		Year number (1978-??)
	hh		Hour (0 - 23)
	mm		Minutes (0 - 59)

Returns :

	<value>		0 if ok inputs
			-1 = bad year
			-2 = bad month
			-3 = bad day of month
	*id		Internal date value
	*it		Internal time value

*/

cvedid (id, it, m, d, y, hh, mm)

int		*id, *it;		/* Addr of date and time variables */
int		m, d, y, hh, mm;	/* Date and time component values */

{
IND	int	i,j;			/* Scratch */

*it = hh*60+mm;				/* Takes care of time */

if ((y < 1978) || (y > 2070))
    return (-1);

mdtbl[1] = 28;				/* Setup February */
if (y%4 == 0)				/* if leap year */
    mdtbl[1] = 29;

m--;					/* Make month and day zero-based */
d--;
if ((m < 0) || (m > 11))		/* Check out month */
    return (-2);
if ((d < 0) || (d >= mdtbl[m]))		/* Check out day of month */
    return (-3);

i = 0;					/* Calculate days */
for (j=0; j < m; j++)
    i += mdtbl[j];
i += d;
i += (y-1978)*365;
i += (y-1976)/4;

*id = i+1;				/* Return day */

return (0);				/* Give good status */
}
/*

*//* cvided (id, it, m, d, y, hh, mm)

	Convert internal date/time values to external values


Accepts :

	id		Date in internal form
	it		Time in internal form
	*m		Where to put month number
	*d		Where to put day number
	*y		Where to put year number
	*hh		Where to put hours
	*mm		Where to put minutes


Returns :

	*m		Month number (1-12)
	*d		Day number (1-31)
	*y		Year number (1978-??)
	*hh		Hour (0-23)
	*mm		Minutes (0-59)

*/

cvided (id, it, m, d, y, hh, mm)

int		id, it;			/* Internal date/time */
int		*m, *d, *y, *hh, *mm;	/* Where to put components */

{
IND	int	i,j;			/* Scratch */
IND	int	yr,ly,mo,day;		/* Various values */

i = id-1;				/* day 1 = Jan 1 1978 */
ly = (i+672)/1461;			/* Number of leap days passed. */
yr = (i-ly)/365;			/* Number of full years passed */
i = i-(yr*365)-((yr+1)/4);		/* Number of day in this year */
yr = yr+1978;				/* What year it is */
mdtbl[1] = 28;				/* Presume not leap year */
if (yr%4 == 0)				/* If is */
    mdtbl[1] = 29;			/*  then set feb days */
for (j=0,mo=0; j <= i; mo++)		/* Find month */
    j = j+mdtbl[mo];			/* Add days */

j = j-mdtbl[--mo];			/* Subtract off last month */
day = (i-j)+1;				/* Get real day. */

*y = yr;				/* Return component values */
*m = mo+1;
*d = day;
*hh = it/60;
*mm = it%60;
}