; ARK02PAT.AZM
; ----------
;  This is a patch file for ARK02.COM that will set the date and time on all 
;  members to be added or updated to the system date and time.  To install for 
;  your system, write a routine at SYSDT: which fills the bytes at
;  MONTH,DAY,YEAR,HOUR,MIN, and SEC with the appropriate values.  (If,
;  for instance, you have system date but not time, just fill in the date;
;  the time will default to midnight.)  As it stands this file is configured
;  to make a CP/M 3 "get date and time" BDOS call.
;
;  When you're ready to do the patch, assemble with Z1 (included) or some other
;  assembler:
;    Z1 ARKPAT
;  and overlay with DDT, or (better) Ron Fowler's MLOAD:
;    MLOAD ARK02.COM,ARKPAT
;  And et voila! ARK will now fill in the system date & time.
;
;  Acknowledgements:
;    First of all, of course, Thom Henderson for inventing the MSDOS ARC format!
;    Brian Moore for porting and hand-optimizing (ugh!!) ARK02.
;    Tom P. Douglas for digging into ARK02 and locating ARKDATE:, and
;      releasing ARKDATER.LBR.  This program patched ARK to permanently
;      change the default date and time.
;    Steven G. Greenberg, for his LDIR-B library directory program, from
;      which the code to interpret a DRI date was lifted almost unchanged.
;
;---------------------------------------------------------------------------
;
	ORG	100h
	JP	GETDT		;get date before beginning program
 
START:	EQU	2A21H		;ARK has a JP 2A21H at 100h, which we overlaid
ENDPRG:	EQU	4901H		;This is 1 byte after the last page of ARK
ARKDATE: EQU	453EH		;Address of default date-and-time within ARK

;
; KAYPRO RTC EQUATES
;

PIOADD	EQU	0FH		; pio address
CLKADD	EQU	20H		; rtc register select
CLKCTL	EQU	22H		; rtc mode control
CLKDAT	EQU	24H		; rtc data
MONRTC	EQU	07H		; rtc months register
DAYRTC	EQU	06H		; rtc days register
HRSRTC	EQU	04H		; rtc hours register
MINRTC	EQU	03H		; rtc minutes register
SECRTC	EQU	02H		; rtc seconds register

	ORG	ENDPRG

MONTBL: DB	31		;This is the table of month lengths used
FEB:	DB	28,31,30,31,30,31,31,30,31,30,31
				;in the SYSDAT routine.  Note!!! If the
				;SYSDAT routine in the original ARKPAT.AZM
				;is used, MONTBL MUST BEGIN AT xx01h (i.e.
				;1 byte after a page boundary).

MONTH:	DB	0		;these values will be filled in by SYSDT
DAY:	DB	0
YEAR:	DB	0
HOUR:	DB	0
MIN:	DB	0
SEC:	DB	0

ADDIT:		;subroutine to add A to HL &shift B bits right
	ADD	A,L		;low byte
	LD	L,A		;save it
	LD	A,H		;high byte
	ADC	A,0		;include possible carry
	LD	H,A		;save it
	INC	B		;is B zero?
	DEC	B
	RET	Z		;yes, don't shift
SHIFTR:	ADD	HL,HL		;shift left one bit
	DJNZ	SHIFTR		;loop B times
	RET			;return

GETDT:	CALL	SYSDT		;fill in date and time
	LD	HL,0		;clean slate
	LD	A,(YEAR)	;get year
	SUB	80		;MSDOS dates begin with 1980
	LD	B,4		;shift 4 bits
	CALL	ADDIT		;do it
	LD	A,(MONTH)	;get month
	LD	B,5		;shift 5 more bits
	CALL	ADDIT		;do it
	LD	A,(DAY)		;get day
	CALL	ADDIT		;shift zero bits
	LD	(ARKDATE),HL	;save into ARK
	LD	HL,0		;clean slate
	LD	A,(HOUR)	;get hour
	LD	B,6		;shift 6 bits
	CALL	ADDIT		;do it
	LD	A,(MIN)		;get minute
	LD	B,4		;shift 4 bits
	CALL	ADDIT		;do it
	LD	A,(SEC)		;get second
	LD	B,1		;shift 1 bit
	CALL	ADDIT		;do it
	LD	(ARKDATE+2),HL	;save into ARK
	JP	START		;continue with ARK program
;
BCD2BIN:	;subroutine to convert from BCD to binary
	LD	B,0		;zero counter
	OR	A		;if BCD is zero, get out
	RET	Z
BBLOOP: INC	B		;count one 
	DEC	A		;dec one (BCD)
	DAA
	JR	NZ,BBLOOP	;continue if not done
	LD	A,B		;load binary value
	RET			;done
;
CPM3DT:		;data area filled by BDOS
CJUL:	DW	0		;days since 31 Dec 79
CHR:	DB	0		;hour (BCD)
CMIN:	DB	0		;min (BCD)
CSEC:	DB	0		;sec (BCD)

SYSDT:

;
; FETCH RTC DATA
;

	LD	A,PIOADD	; set rtc status
	OUT	CLKCTL,A

	LD	A,88H		; year for kaypro
	CALL	BCD2BIN
	LD	(YEAR),A

	LD	A,MONRTC	; get month
	CALL	GETDRI
	CALL	BCD2BIN
	LD	(MONTH),A

	LD	A,DAYRTC	; get day
	CALL	GETDRI
	CALL	BCD2BIN
	LD	(DAY),A

	LD	A,HRSRTC	; get hour
	CALL	GETDRI
	CALL	BCD2BIN
	LD	(HOUR),A

	LD	A,MINRTC	; get minute
	CALL	GETDRI
	CALL	BCD2BIN
	LD	(MIN),A

	LD	A,SECRTC	; get second
	CALL	GETDRI
	CALL	BCD2BIN
	LD	(SEC),A

;
; GET DATE/TIME FROM RTC SUBROUTINE
;

ŠGETDRI:	OUT	CLKADD,A	; output rtc address
	IN	A,CLKDAT	; input rtc data
	RET

;----------------------------
; The rest of the code is lifted almost without change from Steven G. 
; Greenberg's LDIR-B utility (release 1.2).  Many thanks.
	LD	A,78		; Init to 1978
	LD	DE,365		; Amount to subtract per year (except leap)
	LD	B,28		; # of days in Feb for current year
;
YRLP:	AND	A		; Clear carry
	SBC	HL,DE		; Subtract 1 year
	JR	Z,GOTYR
	JR	C,GOTYR		; If carry, we've gone too far
	INC	A		; Else incr year by one 
	AND	A
	SBC	HL,DE		; Repeat for the following [non-leap] year
	JR	Z,GOTYR
	JR	C,GOTYR
	INC	A
	INC	B		; The following year IS a leap year
	INC	DE		; So use 366 for DE and flag B with a "29"
	AND	A
	SBC	HL,DE
	JR	Z,GOTYR
	JR	C,GOTYR
	INC	A
	DEC	DE		; Put year and # of Feb days back to normal
	DEC	B
	AND	A
	SBC	HL,DE		; Repeat for one more [non-leap] year
	JR	Z,GOTYR
	JR	C,GOTYR
	INC	A
	JR	YRLP		; And loop
;
;............................................................................
;
GOTYR:	ADD	HL,DE		; Reverse the last subtraction with current val
	LD	(YEAR),A	; The correct year value
	LD	A,B		; And save current Feb val for future ref
	LD	(FEB),A
	LD	BC,MONTBL	; Table of # of days/month
;
MNTHLP:	LD	A,(BC)		; Get # of days
	LD	E,A		; Put it in DE
	LD	D,0
	AND	A
	SBC	HL,DE		; Subtract
	JR	Z,GOTMON
	JR	C,GOTMON	; If carry, we've gone too far again
	INC	BC		; Else move ahead to the next month
	LD	A,C
	CP	13		; (table is <256 bytes, so this is OK)
	JR	NZ,MNTHLP
;
GOTMON:	ADD	HL,DE		; Once again, add back in
	LD	A,C		; month #
	LD	(MONTH),A
	LD	A,L		; The remainder should be the day#
OKD:	LD	(DAY),A
	RET			; And that's it!
;