RomWBW/Source/HBIOS/acia.asm

;
;==================================================================================================
; ACIA DRIVER (SERIAL PORT)
;==================================================================================================
;
;  SETUP PARAMETER WORD:
;  +-------+---+-------------------+ +---+---+-----------+---+-------+
;  |       |RTS| ENCODED BAUD RATE | |DTR|XON|  PARITY   |STP| 8/7/6 |
;  +-------+---+---+---------------+ ----+---+-----------+---+-------+
;    F   E   D   C   B   A   9   8     7   6   5   4   3   2   1   0
;       -- MSB (D REGISTER) --           -- LSB (E REGISTER) --
;
;
;  ACIA STATUS REGISTER:
;
;       D7      D6      D5      D4      D3      D2      D1      D0
;     +-------+-------+-------+-------+-------+-------+-------+-------+
;     | /IRQ  | PE    | OVRN  | FE    | /CTS  | /DCD  | TDRE  | RDRF  |
;     +-------+-------+-------+-------+-------+-------+-------+-------+
;
;  ACIA CONTROL REGISTER:
;
;       D7      D6      D5      D4      D3      D2      D1      D0
;     +-------+-------+-------+-------+-------+-------+-------+-------+
;     | RIE   | TC2   | TC1   | WS3   | WS2   | WS1   | CDS2  | CDS1  |
;     +-------+-------+-------+-------+-------+-------+-------+-------+
;
;	RIE:	RECEIVE INTERRUPT ENABLE (RECEIVE DATA REGISTER FULL)
;
;	TC:	TRANSMIT CONTROL (TRANSMIT DATA REGISTER EMPTY)
;		0 0 - /RTS=LOW, TDRE INT DISABLED
;		0 1 - /RTS=LOW, TDRE INT ENABLED
;		1 0 - /RTS=HIGH, TDRE INT DISABLED
;		1 1 - /RTS=LOW, TRANSMIT BREAK, TDRE INT DISABLED
;	
;	WS:	WORD SELECT (DATA BITS, PARITY, STOP BITS)
;		0 0 0 - 7,E,2
;		0 0 1 - 7,O,2
;		0 1 0 - 7,E,1
;		0 1 1 - 7,O,1
;		1 0 0 - 8,N,2
;		1 0 1 - 8,N,1
;		1 1 0 - 8,E,1
;		1 1 1 - 8,O,1
;
;	CDS:	COUNTER DIVIDE SELECT
;		0 0 - DIVIDE BY 1
;		0 1 - DIVIDE BY 16
;		1 0 - DIVIDE BY 64
;		1 1 - MASTER RESET
;
ACIA_BUFSZ	.EQU	32		; RECEIVE RING BUFFER SIZE
;
ACIA_NONE       .EQU    0
ACIA_ACIA       .EQU    1
;
ACIA_RTSON	.EQU	%00000000	; BIT MASK TO ASSERT RTS
ACIA_RTSOFF	.EQU	%01000000	; BIT MASK TO DEASSERT RTS
;
#IF (INTMODE > 1)
        .ECHO   "*** ERROR: UNSUPPORTED INTMODE FOR ACIA DRIVER!!!\n"
        !!!     ; FORCE AN ASSEMBLY ERROR
#ENDIF
;
;
;
ACIA_PREINIT:
;
; SETUP THE DISPATCH TABLE ENTRIES
; NOTE: INTS WILL BE DISABLED WHEN PREINIT IS CALLED AND THEY MUST REMIAIN
; DISABLED.
;
        LD      B,ACIA_CFGCNT		; LOOP CONTROL
        XOR     A                       ; ZERO TO ACCUM
        LD      (ACIA_DEV),A            ; CURRENT DEVICE NUMBER
	LD	IY,ACIA_CFG		; POINT TO START OF CFG TABLE
ACIA_PREINIT0:
	PUSH	BC			; SAVE LOOP CONTROL
	CALL	ACIA_INITUNIT		; HAND OFF TO GENERIC INIT CODE
	POP	BC			; RESTORE LOOP CONTROL
;
	LD	A,(IY+1)		; GET THE ACIA TYPE DETECTED
	OR	A			; SET FLAGS
	JR	Z,ACIA_PREINIT2		; SKIP IT IF NOTHING FOUND
;	
	PUSH	BC			; SAVE LOOP CONTROL
	PUSH	IY			; CFG ENTRY ADDRESS
	POP	DE			; ... TO DE
	LD	BC,ACIA_FNTBL		; BC := FUNCTION TABLE ADDRESS
	CALL	NZ,CIO_ADDENT		; ADD ENTRY IF ACIA FOUND, BC:DE
	POP	BC			; RESTORE LOOP CONTROL
;
ACIA_PREINIT2:	
	LD	DE,ACIA_CFGSIZ		; SIZE OF CFG ENTRY
	ADD	IY,DE			; BUMP IY TO NEXT ENTRY
	DJNZ	ACIA_PREINIT0		; LOOP UNTIL DONE
;
ACIA_PREINIT3:
	XOR	A			; SIGNAL SUCCESS
	RET				; AND RETURN
;
; ACIA INITIALIZATION ROUTINE
;
ACIA_INITUNIT:
        CALL    ACIA_DETECT             ; DETERMINE ACIA TYPE
        LD      (IY+1),A                ; SAVE IN CONFIG TABLE
        OR      A                       ; SET FLAGS
        RET     Z                       ; ABORT IF NOTHING THERE

        ; UPDATE WORKING ACIA DEVICE NUM
        LD      HL,ACIA_DEV             ; POINT TO CURRENT UART DEVICE NUM
        LD      A,(HL)                  ; PUT IN ACCUM
        INC     (HL)                    ; INCREMENT IT (FOR NEXT LOOP)
        LD      (IY),A                  ; UPDATE UNIT NUM
;
#IF (INTMODE == 1)
        ; ADD IM1 INT CALL LIST ENTRY
        LD      L,(IY+8)		; GET INT HANDLER PTR
        LD      H,(IY+9)		; ... INTO HL
        CALL    HB_ADDIM1               ; ADD TO IM1 CALL LIST
#ENDIF
;
#IF (INTMODE > 1)
	.ECHO	"*** ERROR: ACIA DEVICE DOES NOT SUPPORT INTMODE 2!!!\n"
	!!!	; FORCE AN ASSEMBLY ERROR
#ENDIF
;
	; IT IS EASY TO SPECIFY A SERIAL CONFIG THAT CANNOT BE IMPLEMENTED
	; DUE TO THE CONSTRAINTS OF THE ACIA.  HERE WE FORCE A GENERIC
	; FAILSAFE CONFIG ONTO THE CHANNEL.  IF THE SUBSEQUENT "REAL"
	; CONFIG FAILS, AT LEAST THE CHIP WILL BE ABLE TO SPIT DATA OUT
	; AT A RATIONAL BAUD/DATA/PARITY/STOP CONFIG.
	CALL	ACIA_INITSAFE
;
        ; SET DEFAULT CONFIG
        LD      DE,-1                   ; LEAVE CONFIG ALONE
        ; CALL INITDEV TO IMPLEMENT CONFIG, BUT NOTE THAT WE CALL
        ; THE INITDEV ENTRY POINT THAT DOES NOT ENABLE/DISABLE INTS!
        JP      ACIA_INITDEVX           ; IMPLEMENT IT AND RETURN
;
;
;
ACIA_INIT:
	LD	B,ACIA_CFGCNT		; COUNT OF POSSIBLE ACIA UNITS
	LD	IY,ACIA_CFG		; POINT TO START OF CFG TABLE
ACIA_INIT1:
	PUSH	BC			; SAVE LOOP CONTROL
	LD	A,(IY+1)		; GET ACIA TYPE
	OR	A			; SET FLAGS
	CALL	NZ,ACIA_PRTCFG		; PRINT IF NOT ZERO
	POP	BC			; RESTORE LOOP CONTROL
	LD	DE,ACIA_CFGSIZ		; SIZE OF CFG ENTRY
	ADD	IY,DE			; BUMP IY TO NEXT ENTRY
	DJNZ	ACIA_INIT1		; LOOP TILL DONE
;
	XOR	A			; SIGNAL SUCCESS
	RET				; DONE
;
; INTERRUPT HANDLERS
;
#IF (INTMODE == 0)
;
; NO INTERRUPT HANDLERS UNDER INTMODE 0.  GENERATE A PANIC
; IF SOMETHING TRIES TO CALL THEM.
;
ACIA0_INT:
ACIA1_INT:
	CALL	PANIC
;
#ENDIF
;
#IF (INTMODE > 0)
;
ACIA0_INT:
	LD	IY,ACIA0_CFG		; POINT TO ACIA0 CFG
	JR	ACIA_INTRCV		; TRY TO RECEIVE FROM IT AND RETURN
;
#IF (ACIACNT >= 2)
;
ACIA1_INT:
	LD	IY,ACIA1_CFG		; POINT TO ACIA1 CFG
	JR	ACIA_INTRCV		; TRY TO RECEIVE FROM IT AND RETURN
;
#ENDIF
;
; HANDLE INT FOR A SPECIFIC CHANNEL
; BASED ON UNIT CFG POINTED TO BY IY
;
ACIA_INTRCV:
	; CHECK TO SEE IF SOMETHING IS ACTUALLY THERE
	LD	C,(IY+3)		; CMD/STAT PORT TO C
	IN	A,(C)			; GET STATUS
	AND	$01			; ISOLATE RECEIVE READY BIT
	RET	Z			; NOTHING AVAILABLE ON CURRENT CHANNEL
;
ACIA_INTRCV1:
	; RECEIVE CHARACTER INTO BUFFER
        INC     C                       ; DATA PORT
	IN	A,(C)			; READ PORT
        DEC     C                       ; BACK TO CONTROL PORT
	LD	B,A			; SAVE BYTE READ
	LD	L,(IY+6)		; SET HL TO
	LD	H,(IY+7)		; ... START OF BUFFER STRUCT
	LD	A,(HL)			; GET COUNT
	CP	ACIA_BUFSZ		; COMPARE TO BUFFER SIZE
	JR	Z,ACIA_INTRCV4		; BAIL OUT IF BUFFER FULL, RCV BYTE DISCARDED
	INC	A			; INCREMENT THE COUNT
	LD	(HL),A			; AND SAVE IT
	CP	ACIA_BUFSZ / 2		; BUFFER GETTING FULL?
	JR	NZ,ACIA_INTRCV2		; IF NOT, BYPASS CLEARING RTS
	LD	A,(ACIA_CMD)		; CONFIG BYTE W/O RTS BIT
	OR	ACIA_RTSOFF		; CLEAR RTS
	OUT	(C),A			; DO IT
ACIA_INTRCV2:
	INC	HL			; HL NOW HAS ADR OF HEAD PTR
	PUSH	HL			; SAVE ADR OF HEAD PTR
	LD	A,(HL)			; DEREFERENCE HL
	INC	HL
	LD	H,(HL)
	LD	L,A			; HL IS NOW ACTUAL HEAD PTR
	LD	(HL),B			; SAVE CHARACTER RECEIVED IN BUFFER AT HEAD
	INC	HL			; BUMP HEAD POINTER
	POP	DE			; RECOVER ADR OF HEAD PTR
	LD	A,L			; GET LOW BYTE OF HEAD PTR
	SUB	ACIA_BUFSZ+4		; SUBTRACT SIZE OF BUFFER AND POINTER
	CP	E			; IF EQUAL TO START, HEAD PTR IS PAST BUF END
	JR	NZ,ACIA_INTRCV3		; IF NOT, BYPASS
	LD	H,D			; SET HL TO
	LD	L,E			; ... HEAD PTR ADR
	INC	HL			; BUMP PAST HEAD PTR
	INC	HL
	INC	HL
	INC	HL			; ... SO HL NOW HAS ADR OF ACTUAL BUFFER START
ACIA_INTRCV3:
	EX	DE,HL			; DE := HEAD PTR VAL, HL := ADR OF HEAD PTR
	LD	(HL),E			; SAVE UPDATED HEAD PTR
	INC	HL
	LD	(HL),D
	; CHECK FOR MORE PENDING...
	IN	A,(C)			; GET STATUS
	RRA				; READY BIT TO CF
	JR	C,ACIA_INTRCV1		; IF SET, DO SOME MORE
ACIA_INTRCV4:
	OR	$FF			; NZ SET TO INDICATE INT HANDLED
	RET				; AND RETURN
;
#ENDIF
;
; DRIVER FUNCTION TABLE
;
ACIA_FNTBL:
        .DW     ACIA_IN
        .DW     ACIA_OUT
        .DW     ACIA_IST
        .DW     ACIA_OST
        .DW     ACIA_INITDEV
        .DW     ACIA_QUERY
        .DW     ACIA_DEVICE
#IF (($ - ACIA_FNTBL) != (CIO_FNCNT * 2))
        .ECHO   "*** INVALID ACIA FUNCTION TABLE ***\n"
        !!!     ; FORCE AN ASSEMBLY ERROR
#ENDIF
;
;
;
#IF (INTMODE == 0)
;
ACIA_IN:
        CALL    ACIA_IST                ; CHAR WAITING?
        JR      Z,ACIA_IN               ; LOOP IF NOT
        LD      C,(IY+3)                ; C := ACIA BASE PORT
        INC     C                       ; BUMP TO DATA PORT
        IN      E,(C)                   ; GET BYTE
        XOR     A                       ; SIGNAL SUCCESS
        RET
;
#ELSE
;
ACIA_IN:
	CALL	ACIA_IST		; SEE IF CHAR AVAILABLE
	JR	Z,ACIA_IN		; LOOP UNTIL SO
	HB_DI				; AVOID COLLISION WITH INT HANDLER
	LD	L,(IY+6)		; SET HL TO
	LD	H,(IY+7)		; ... START OF BUFFER STRUCT
	LD	A,(HL)			; GET COUNT
	DEC	A			; DECREMENT COUNT
	LD	(HL),A			; SAVE UPDATED COUNT
	CP	ACIA_BUFSZ / 4		; BUFFER LOW THRESHOLD
	JR	NZ,ACIA_IN1		; IF NOT, BYPASS SETTING RTS
	LD	C,(IY+3)		; C IS CMD/STATUS PORT ADR
	LD	A,(ACIA_CMD)		; CONFIG BYTE W/O RTS BIT
	OR	ACIA_RTSON		; SET RTS
	OUT	(C),A			; DO IT
ACIA_IN1:
	INC	HL
	INC	HL
	INC	HL			; HL NOW HAS ADR OF TAIL PTR
	PUSH	HL			; SAVE ADR OF TAIL PTR
	LD	A,(HL)			; DEREFERENCE HL
	INC	HL
	LD	H,(HL)
	LD	L,A			; HL IS NOW ACTUAL TAIL PTR
	LD	C,(HL)			; C := CHAR TO BE RETURNED
	INC	HL			; BUMP TAIL PTR
	POP	DE			; RECOVER ADR OF TAIL PTR
	LD	A,L			; GET LOW BYTE OF TAIL PTR
	SUB	ACIA_BUFSZ+2		; SUBTRACT SIZE OF BUFFER AND POINTER
	CP	E			; IF EQUAL TO START, TAIL PTR IS PAST BUF END
	JR	NZ,ACIA_IN2		; IF NOT, BYPASS
	LD	H,D			; SET HL TO
	LD	L,E			; ... TAIL PTR ADR
	INC	HL			; BUMP PAST TAIL PTR
	INC	HL			; ... SO HL NOW HAS ADR OF ACTUAL BUFFER START
ACIA_IN2:
	EX	DE,HL			; DE := TAIL PTR VAL, HL := ADR OF TAIL PTR
	LD	(HL),E			; SAVE UPDATED TAIL PTR
	INC	HL
	LD	(HL),D
	LD	E,C			; MOVE CHAR TO RETURN TO E
	HB_EI				; INTERRUPTS OK AGAIN
	XOR	A			; SIGNAL SUCCESS
	RET				; AND DONE
;
#ENDIF
;
;
;
ACIA_OUT:
        CALL    ACIA_OST                ; READY FOR CHAR?
        JR      Z,ACIA_OUT              ; LOOP IF NOT
        LD      C,(IY+3)                ; C := ACIA CMD PORT
        INC     C                       ; BUMP TO DATA PORT
        OUT     (C),E                   ; SEND CHAR FROM E
        XOR     A                       ; SIGNAL SUCCESS
        RET
;
;
;
#IF (INTMODE == 0)
;
ACIA_IST:
        LD      C,(IY+3)                ; STATUS PORT
        IN      A,(C)                   ; GET STATUS
        AND     $01                     ; ISOLATE BIT 0 (RX READY)
        JP      Z,CIO_IDLE              ; NOT READY, RETURN VIA IDLE PROCESSING
        XOR     A                       ; ZERO ACCUM
        INC     A                       ; ASCCUM := 1 TO SIGNAL 1 CHAR WAITING
        RET                             ; DONE
;
#ELSE
;
ACIA_IST:
	LD	L,(IY+6)		; GET ADDRESS
	LD	H,(IY+7)		; ... OF RECEIVE BUFFER
	LD	A,(HL)			; BUFFER UTILIZATION COUNT
	OR	A			; SET FLAGS
	JP	Z,CIO_IDLE		; NOT READY, RETURN VIA IDLE PROCESSING
	RET
;
#ENDIF
;
;
;
ACIA_OST:
        LD      C,(IY+3)                ; CMD PORT
        IN      A,(C)                   ; GET STATUS
        AND     $02                     ; ISOLATE BIT 2 (TX EMPTY)
        JP      Z,CIO_IDLE              ; NOT READY, RETURN VIA IDLE PROCESSING
        XOR     A                       ; ZERO ACCUM
        INC     A                       ; ACCUM := 1 TO SIGNAL 1 BUFFER POSITION
        RET                             ; DONE
;
;
;
ACIA_INITDEV:
        HB_DI                           ; AVOID CONFLICTS
        CALL    ACIA_INITDEVX           ; DO THE REAL WORK
        HB_EI                           ; INTS BACK ON
        RET                             ; DONE
;
; THIS ENTRY POINT BYPASSES DISABLING/ENABLING INTS WHICH IS REQUIRED BY
; PREINIT ABOVE.  PREINIT IS NOT ALLOWED TO ENABLE INTS!
;
ACIA_INITDEVX:
;
#IF (ACIADEBUG)
	CALL	NEWLINE
	PRTS("ACIA$")
	LD	A,(IY+2)
	CALL	PRTDECB
	CALL	COUT
	CALL	PC_COLON
#ENDIF
;
	; TEST FOR -1 WHICH MEANS USE CURRENT CONFIG (JUST REINIT)
	LD	A,D			; TEST DE FOR
	AND	E			; ... VALUE OF -1
	INC	A			; ... SO Z SET IF -1
	JR	NZ,ACIA_INITDEV1	; IF DE == -1, REINIT CURRENT CONFIG
;
	; LOAD EXISTING CONFIG TO REINIT
	LD	E,(IY+4)		; LOW BYTE
	LD	D,(IY+5)		; HIGH BYTE	
;
ACIA_INITDEV1:
;
#IF (ACIADEBUG)
	PUSH	DE
	POP	BC
	PRTS(" CFG=$")
	CALL	PRTHEXWORD
#ENDIF
;
	LD	A,E			; GET CONFIG LSB
	AND	$E0			; CHECK FOR DTR, XON, PARITY=MARK/SPACE
	JR	NZ,ACIA_INITFAIL	; IF ANY BIT SET, FAIL, NOT SUPPORTED
;
	LD	A,D			; GET CONFIG MSB
	AND	$1F			; ISOLATE ENCODED BAUD RATE
;
#IF (ACIADEBUG)
	PRTS(" ENC=$")
	CALL	PRTHEXBYTE
#ENDIF
;
	; BAUD RATE
	PUSH	DE			; SAVE REQUESTED CONFIG
	LD	L,(IY+10)		; LOAD CLK FREQ
	LD	H,(IY+11)		; ... INTO DE:HL
	LD	E,(IY+12)		; ... "
	LD	D,(IY+13)		; ... "
	LD	C,75			; BAUD RATE ENCODING CONSTANT
	CALL	ENCODE			; C = TEST BAUD RATE (ENCODED) = BAUDTST
	POP	DE			; GET REQ CONFIG BACK, D = BAUDREQ
;
	; BIT 4 (DIV 3) OF BAUDREQ AND BAUDTST MUST MATCH!
	LD	A,C			; A = BAUDTST
	XOR	D			; XOR WITH BAUDREQ
	BIT	4,A			; DO BIT 4 VALS MATCH?
	JR	NZ,ACIA_INITFAIL	; IF NOT, BAIL OUT
;	
	LD	A,C			; BAUDTST TO A
	AND	$0F			; ISOLATE DIV 2 BAUD BITS
	LD	C,A			; C = BAUDTST
;	
	LD	A,D			; MSB W/ BAUD RATE TO A
	AND	$0F			; ISOLATE DIV 2 BAUD BITS
	LD	L,A			; L = BAUDREQ
;	
	LD	A,C			; A = BAUDTST
	LD	B,%00000000		; ACIA VAL FOR DIV 1
	CP	L			; BAUDTST = BAUDREQ?
	JR	Z,ACIA_INITBROK		; IF MATCH, WE ARE DONE
;	
	SUB	4			; DIVIDE BY 16 (NOW DIV 16 TOT)
	JR	C,ACIA_INITFAIL		; FAIL IF UNDERFLOW
	LD	B,%00000001		; ACIA VAL FOR DIV 16
	CP	L			; BAUDTST = BAUDREQ?
	JR	Z,ACIA_INITBROK		; IF MATCH, WE ARE DONE
;	
	SUB	2			; DIVIDE BY 4 (NOW DIV 64 TOT)
	JR	C,ACIA_INITFAIL		; FAIL IF UNDERFLOW
	LD	B,%00000010		; ACIA R4 VAL FOR DIV 32
	CP	L			; BAUDTST = BAUDREQ?
	JR	Z,ACIA_INITBROK		; IF MATCH, WE ARE DONE
;
ACIA_INITFAIL:
;
#IF (ACIADEBUG)
	PRTS(" BAD CFG$")	
#ENDIF
;
	OR	$FF
	RET				; INVALID CONFIG
;	
ACIA_INITBROK:
	; REG B HAS WORKING CONFIG VALUE W/ BAUD RATE BITS
	LD	C,B			; WORKING VAL TO C
	LD	A,E			; LSB OF INCOMING CONFIG
	AND	%00111111		; ISOLATE LOW 6 BITS TO COMPARE
	LD	B,8			; WORD SELECT TABLE SIZE
	LD	HL,ACIA_WSTBL		; POINT TO TABLE
ACIA_INITWS:
	CP	(HL)			; MATCH?
	JR	Z,ACIA_INITWS2		; IF SO, REG B HAS ACIA VAL + 1
	INC	HL			; NEXT ENTRY
	DJNZ	ACIA_INITWS		; KEEP CHECKING TILL DONE
	JR	ACIA_INITFAIL		; FAIL IF NO MATCH
	
ACIA_WSTBL:
	.DB	%00001011		; 8/O/1
	.DB	%00011011		; 8/E/1
	.DB	%00000011		; 8/N/1
	.DB	%00000111		; 8/N/2
	.DB	%00001010		; 7/O/1
	.DB	%00011010		; 7/E/1
	.DB	%00001110		; 7/O/2
	.DB	%00011110		; 7/E/2

ACIA_INITWS2:
	LD	A,B			; PUT FANAL VALUE IN A
	DEC	A			; ZERO INDEX ADJUSTMENT
	RLA				; MOVE BITS TO
	RLA				; ... PROPER LOCATION
	OR	C			; COMBINE WITH WORKING VALUE
	JR	ACIA_INITGO
;
ACIA_INITSAFE:
	LD	A,%00010110		; DEFAULT CONFIG
;
ACIA_INITGO:
;
#IF (INTMODE > 0)
	OR	%10000000		; ENABLE RCV INT
#ENDIF
;
	LD	(ACIA_CMD),A		; SAVE SHADOW REGISTER
;
#IF (ACIADEBUG)
	PRTS(" CMD=$")
	CALL	PRTHEXBYTE
	LD	DE,65
	CALL	VDELAY			; WAIT FOR FINAL CHAR TO SEND
#ENDIF
;
        ; PROGRAM THE ACIA CHIP
        LD      C,(IY+3)                ; COMMAND PORT
        LD      A,$FF                   ; MASTER RESET
        OUT     (C),A                   ; DO IT
	LD	A,(ACIA_CMD)		; RESTORE CONFIG VALUE
        OUT     (C),A                   ; DO IT
;
#IF (INTMODE > 0)
;
        ; RESET THE RECEIVE BUFFER
        LD      E,(IY+6)
        LD      D,(IY+7)                ; DE := _CNT
        XOR     A                       ; A := 0
        LD      (DE),A                  ; _CNT = 0
        INC     DE                      ; DE := ADR OF _HD
        PUSH    DE                      ; SAVE IT
        INC     DE
        INC     DE
        INC     DE
        INC     DE                      ; DE := ADR OF _BUF
        POP     HL                      ; HL := ADR OF _HD
        LD      (HL),E
        INC     HL
        LD      (HL),D                  ; _HD := _BUF
        INC     HL
        LD      (HL),E
        INC     HL
        LD      (HL),D                  ; _TL := _BUF
;
#ENDIF
;
        XOR     A                       ; SIGNAL SUCCESS
        RET                             ; RETURN
;
;
;
ACIA_QUERY:
        LD      E,(IY+4)                ; FIRST CONFIG BYTE TO E
        LD      D,(IY+5)                ; SECOND CONFIG BYTE TO D
        XOR     A                       ; SIGNAL SUCCESS
        RET                             ; DONE
;
;
;
ACIA_DEVICE:
        LD      D,CIODEV_ACIA           ; D := DEVICE TYPE
        LD      E,(IY)                  ; E := PHYSICAL UNIT
        LD      C,$00                   ; C := DEVICE TYPE, 0x00 IS RS-232
        XOR     A                       ; SIGNAL SUCCESS
        RET
;
; ACIA DETECTION ROUTINE
;
ACIA_DETECT:
	LD	A,(IY+3)		; BASE PORT ADDRESS
	LD	C,A			; PUT IN C FOR I/O
        CALL    ACIA_DETECT2            ; CHECK IT
        JR      Z,ACIA_DETECT1          ; FOUND IT, RECORD IT
        LD      A,ACIA_NONE             ; NOTHING FOUND
        RET                             ; DONE
;       
ACIA_DETECT1:   
        ; ACIA FOUND, RECORD IT 
        LD      A,ACIA_ACIA             ; RETURN CHIP TYPE
        RET                             ; DONE
;
ACIA_DETECT2:
        ; LOOK FOR ACIA AT PORT ADDRESS IN C
        LD      A,$03                   ; MASTER RESET
        OUT     (C),A                   ; DO IT
        IN      A,(C)                   ; GET STATUS
        OR      A                       ; CHECK FOR ZERO
        RET     NZ                      ; RETURN IF NOT ZERO
        LD      A,$02                   ; CLEAR MASTER RESET
        OUT     (C),A                   ; DO IT
	IN	A,(C)			; GET STATUS AGAIN
        ; CHECK FOR EXPECTED BITS:
        ;   TDRE=1, DCD & CTS = 0
        AND     %00001110               ; BIT MASK FOR "STABLE" BITS
        CP      %00000010               ; EXPECTED VALUE
        RET                             ; RETURN RESULT, Z = CHIP FOUND
;
;
;
ACIA_PRTCFG:
        ; ANNOUNCE PORT
        CALL    NEWLINE                 ; FORMATTING
        PRTS("ACIA$")                   ; FORMATTING
        LD      A,(IY)                  ; DEVICE NUM
        CALL    PRTDECB                 ; PRINT DEVICE NUM
        PRTS(": IO=0x$")                ; FORMATTING
        LD      A,(IY+3)                ; GET BASE PORT
        CALL    PRTHEXBYTE              ; PRINT BASE PORT

        ; PRINT THE ACIA TYPE
        CALL    PC_SPACE                ; FORMATTING
        LD      A,(IY+1)                ; GET ACIA TYPE BYTE
        RLCA                            ; MAKE IT A WORD OFFSET
        LD      HL,ACIA_TYPE_MAP        ; POINT HL TO TYPE MAP TABLE
        CALL    ADDHLA                  ; HL := ENTRY
        LD      E,(HL)                  ; DEREFERENCE
        INC     HL                      ; ...
        LD      D,(HL)                  ; ... TO GET STRING POINTER
        CALL    WRITESTR                ; PRINT IT
;
        ; ALL DONE IF NO ACIA WAS DETECTED
        LD      A,(IY+1)                ; GET ACIA TYPE BYTE
        OR      A                       ; SET FLAGS
        RET     Z                       ; IF ZERO, NOT PRESENT
;
        PRTS(" MODE=$")                 ; FORMATTING
        LD      E,(IY+4)                ; LOAD CONFIG
        LD      D,(IY+5)                ; ... WORD TO DE
        CALL    PS_PRTSC0               ; PRINT CONFIG
;
        XOR     A
        RET
;
;
;
ACIA_TYPE_MAP:
                .DW     ACIA_STR_NONE
                .DW     ACIA_STR_ACIA

ACIA_STR_NONE   .DB     "<NOT PRESENT>$"
ACIA_STR_ACIA   .DB     "ACIA$"
;
; WORKING VARIABLES
;
ACIA_DEV        .DB     0               ; DEVICE NUM USED DURING INIT
ACIA_CMD	.DB	0		; COMMAND PORT SHADOW REGISTER
;
#IF (INTMODE == 0)
;
ACIA0_RCVBUF    .EQU    0
ACIA1_RCVBUF    .EQU    0
;
#ELSE
;
; RECEIVE BUFFERS
;
ACIA0_RCVBUF:
ACIA0_BUFCNT    .DB     0               ; CHARACTERS IN RING BUFFER
ACIA0_HD        .DW     ACIA0_BUF       ; BUFFER HEAD POINTER
ACIA0_TL        .DW     ACIA0_BUF       ; BUFFER TAIL POINTER
ACIA0_BUF       .FILL   32,0            ; RECEIVE RING BUFFER
ACIA0_BUFEND    .EQU    $               ; END OF BUFFER
ACIA0_BUFSZ     .EQU    $ - ACIA0_BUF   ; SIZE OF RING BUFFER
;
#IF (ACIACNT >= 2)
;
ACIA1_RCVBUF:
ACIA1_BUFCNT    .DB     0               ; CHARACTERS IN RING BUFFER
ACIA1_HD        .DW     ACIA1_BUF       ; BUFFER HEAD POINTER
ACIA1_TL        .DW     ACIA1_BUF       ; BUFFER TAIL POINTER
ACIA1_BUF       .FILL   32,0            ; RECEIVE RING BUFFER
ACIA1_BUFEND    .EQU    $               ; END OF BUFFER
ACIA1_BUFSZ     .EQU    $ - ACIA1_BUF   ; SIZE OF RING BUFFER
;
#ENDIF
;
#ENDIF
;
; ACIA PORT TABLE
;
ACIA_CFG:
;
ACIA0_CFG:
        ; ACIA MODULE A CONFIG
        .DB     0                       ; DEVICE NUMBER (SET DURING INIT)
        .DB     0                       ; ACIA TYPE (SET DURING INIT)
        .DB     0                       ; MODULE ID
        .DB     ACIA0BASE               ; BASE PORT
        .DW     ACIA0CFG                ; LINE CONFIGURATION
        .DW     ACIA0_RCVBUF            ; POINTER TO RCV BUFFER STRUCT
	.DW     ACIA0_INT		; INT HANDLER POINTER
	.DW	(ACIA0CLK / ACIA0DIV) & $FFFF	; CLOCK FREQ AS
	.DW	(ACIA0CLK / ACIA0DIV) >> 16	; ... DWORD VALUE
;
ACIA_CFGSIZ	.EQU	$ - ACIA_CFG	; SIZE OF ONE CFG TABLE ENTRY
;
#IF (ACIACNT >= 2)
;
ACIA1_CFG:
        ; ACIA MODULE B CONFIG
        .DB     0                       ; DEVICE NUMBER (SET DURING INIT)
        .DB     0                       ; ACIA TYPE (SET DURING INIT)
        .DB     1                       ; MODULE ID
        .DB     ACIA1BASE               ; BASE PORT
        .DW     ACIA1CFG                ; LINE CONFIGURATION
        .DW     ACIA1_RCVBUF            ; POINTER TO RCV BUFFER STRUCT
	.DW     ACIA1_INT		; INT HANDLER POINTER
	.DW	(ACIA1CLK / ACIA1DIV) & $FFFF	; CLOCK FREQ AS
	.DW	(ACIA1CLK / ACIA1DIV) >> 16	; ... DWORD VALUE
;
#ENDIF
;
ACIA_CFGCNT	.EQU    ($ - ACIA_CFG) / ACIA_CFGSIZ