; B5C-CW.INS - Clock routine for the CompuTime/QT clock card.  07/03/85
;						-- by pst
;
;  This routine needs:		BCD2BIN = no
;				BIN2BCD = no
;
;----------------------------------------------------------------
;
;	Note- This is an insert--not an overlay
;
CWBASE	EQU	241		; Base port for board
CLKCMD	EQU	CWBASE		; Clock command port
CLKDATA	EQU	CWBASE+1	; Clock data port (same as command)
CLKREAD	EQU	32		; Read command bit
CLKHOLD	EQU	64		; Hold command bit
;
TIME:	LXI	H,RTCBUF	; Point to RTC buffer
	MVI	C,5		; Set counter for hour tens
	CALL	RDIGIT		; Get hour tens
	CALL	SHFT4		; Save in buffer
	CALL	MULT10		; Multiply by 10
	MOV	B,A		; Save in B reg
	CALL	RDIGIT		; Get hour units in A reg
	CALL	ADDLOW		; Set BCD digit
	ADD	B		; Add tens digit from B
	STA	CCHOUR		; Store for later use
;
;	Minutes
;
	CALL	RDIGIT		; Get minute tens in A reg
	CALL	SHFT4		; Save in buffer
	CALL	MULT10		; Multiply by 10
	MOV	B,A		; Save in B reg
	CALL	RDIGIT		; Get minute units in A reg
	CALL	ADDLOW		; Set BCD digit
	ADD	B		; Add in minutes tens from B
	STA	CCMIN		; Store for later use
;
;	Seconds
;
	CALL	RDIGIT		; Second tens
	CALL	SHFT4
	CALL	RDIGIT		; Second units
	CALL	ADDLOW
;
;	Year
;
	INX	H		; Skip over "19"
	MVI	C,12		; Start with years tens
	CALL	RDIGIT
	CALL	SHFT4
	CALL	RDIGIT		; Years units
	CALL	ADDLOW
;
	CALL	RDIGIT		; Month tens
	CALL	SHFT4
	CALL	RDIGIT		; Month units
	CALL	ADDLOW
;
	CALL	RDIGIT		; Day tens
	CALL	SHFT4
	CALL	RDIGIT		; Day units
	CALL	ADDLOW
;
	XRA	A
	OUT	CLKCMD		; Turn off hold bit
	RET
;
;	Read a digit
;		Command in C
;		Digit returned in A
;		C is decremented
;		Hold bit is set
;
RDIGIT:	MVI	A,CLKHOLD	; Set clock hold command
	OUT	CLKCMD
	XRA	A
RDLP1:	XTHL
	XTHL
	DCR	A
	JNZ	RDLP1
;
	MOV	A,C
	DCR	C
	ORI	CLKREAD
	OUT	CLKDATA		; Select digit
	MVI	A,20
RDLP2:	XTHL
	XTLH
	DCR	A
	JNZ	RDLP2
;
	IN	CLKDATA		; read a digit
	ANI	15		; Strip off any commands
	PUSH	B
	MOV	B,A		; Save in B
	MOV	A,C
	CPI	5		; Was it hour tens digit?
	MOV	A,B		; Get digit back
	JNZ	NOTENS
	ANI	3		; Hour tens gets striped more
NOTENS:	POP	B
	RET
;
;	Multiply register A by 10
;	Destroys 'D'
;
MULT10:	ADD	A		; 2x
	MOV	D,A
	ADD	A		; 4x
	ADD	A		; 8x
	ADD	D		; 10x
	RET
;
;	Shift A to high nibble
;		Stores shifted value in 'M'
;		Destroys 'E'
;		A is left unchanged
;
SHFT4:	MOV	E,A
	ANI	15		; Only handle lower 4 bits
	RLC			; Shift A over 4 bits
	RLC
	RLC
	RLC			
	MOV	M,A		; Save it while we're at it
	MOV	A,E
	RET
;
;	Add in low BCD nibble
;		Gets high nibble from M
;		Stores new BCD byte in M
;		Increments HL
;		Destroyes 'E'
;
ADDLOW:	MOV	E,A
	ANI	15		; Deal with low nibble only
	ORA	M		; Add in high nibble from tens digit
	MOV	M,A		; Save new BCD byte in buffer
	INX	H		; Move on to next location
	MOV	A,E
	RET
;
;  Insert this routine in BYE5 between the IF CLOCK OR RSPEED and ENDIF
;  statements in the area marked +++ Install your clock +++.