comm.asm

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	TITLE	COMM
	PAGE	83,132
;	$Id: comm.asm 1.7 1993/05/31 01:39:23 ahd Exp $
;
;	$Log: comm.asm $
;; Revision 1.7  1993/05/31  01:39:23  ahd
;; Add return to spin loop (fix by Bill Plummer)
;; Drop FIFO size to 8
;;
;; Revision 1.4  1993/05/30  00:20:02  ahd
;; Insert minor delay to allow slow modems to catch up
;;
;; Revision 1.2  1992/12/18  12:08:25  ahd
;; Add Plummer's fix for bad TASM assemble of com_errors
;;
;
; 14-Jun-93 plummer	Add RET to spinloop routine
; 14-Jun-93 plummer	Set FIFO thresholds to 8 rather than 16 bytes
; 18-May-93 plummer	Define IO$DELAY and use in UART type determination
; 16-May-93 plummer	Debug code to printout UART type
; 22-Apr-93 plummer	Make case consistent in "TBuff" so it links properly
;  2-Dec-92 plummer	Fix com_errors() again.  Change got lost.
; Fix com_errors() to avoid problems with tasm.  Plummer, 11/16/92
; 8259 EOI issued after interrupts serviced.  Plummer, 3/25/92
; Fix botch in Set_Baud.  Plummer, 3/20/92
; Put in Gordon Lee's cure from dropped interrupts.  Plummer, 3/19/92
; TEMPORARY ioctl_com().  Plummer, 3/9/92.
; Clear OUT2 bit in UART.  Some machines use it so enable IRQ. Plummer, 3/9/92
; Release send buffer if we can't assign a recv buffer.  Plummer, 3/9/92
; Move EQU's outside of SP_TAB struc definition.  ahd, 3/8/92.
; ahd changes: short jmp's out of range in INST, OPEN ???  (ahd, 3/?/92)
; open_com() leaves DTR unchanged so Drew's autobaud works.  Plummer, 3/2/92
; Missing DX load in close_com() -- FIFO mode not cleared.  Plummer, 3/2/92
; C calling convention does not require saving AX, BX, CX, DX. Plummer 2/23/92
; Flush consideration of the PC Jr.  Wm. W. Plummer, 2/15/92
; Cleanup PUSHF/POPF and CLI/STI useage.  Wm. W. Plummer, 2/15/92
; Make SENDII have Giles Todd's change.  Wm. W. Plummer, 2/15/92
; Changes to Giles Todd's code to support dynamic buffers.  Plummer, 2/3/92
; 26 Jan 92 Giles Todd	Prime THR for UARTs which do not give a Tx empty
;			interrupt when Tx interrupts are enabled.
; S_SIZE & R_SIZE may be set with -D to MASM.  Wm. W. Plummer, 1/19/92
; Assign buffers dynamically.  Wm. W. Plummer, 1/19/92
; Unfix byte length -- I screwed up.  Wm. W. Plummer, 1/15/92
; Fix byte length with specific PARITY select.	Wm. W. Plummer, 1/13/92
; Buffers up to 4096 per AHD.  Wm. W. Plummer, 1/1/92
; Always use FIFO length of 16 on send side.  Wm. W. Plummer, 12/30/91.
; Init DSR and CTS previous state from current status.	Wm. Plummer, 12/30/91.
; UUPC conditional to disable v.24.  Wm. W. Plummer, 12/30/91.
; Buffer sizes up to 2048 per ahd.  Wm. W. Plummer, 12/15/91.
; dtr_on() switches to D connection if CTS&DSR don't come up.  WWP, 12/15/91.
; New dtr_on() logic.  Wm. W. Plummer, 12/11/91
; Fix bad reg. per report from user.  Wm. W. Plummer, 12/11/91
; Semicolon before control-L's for MASM 5.00 per ahd. Wm. W. Plummer, 12/8/91
; Use AHD's handling of COM ports.  Wm. W. Plummer, 11/29/91
; Buffer sizes reduced and required to be 2**N.  Wm. W. Plummer, 11/11/91
; Accomodate V.24 requirements on DTR flaps.  Wm. W. Plummer 10/15/91
; Revised DTR_ON_COM to solve user problem.  Wm. W. Plummer, 10/3/91
; Make time delays independent of CPU speed.  Wm. W. Plummer, 9/16/91
; Use interrupts to trace CD, DSR, Wm. W. Plummer, 9/16/91
; Remove modem control from TXI. Wm. W. Plummer, 9/13/91
; Completely redo the XOFF/XON logic.  Too many races before. Wm. W. Plummer
; Revise interrupt dispatch for speed & function.  William W. Plummer, 9/12/91
; Merge in ahd's changes to flush control Q,S when received as flow control
; SEND buffer allows one byte for a SENDII call.  Avoids flow control
;  lockups. - William W. Plummer, 8/30/91
; Support for NS16550A chip with SILO - William W. Plummer, 8/30/91
; Add modem_status() routine - William W. Plummer, 7/2/91
; Put wrong code under AHD conditional - William W. Plummer, 7/2/91
; Change TITLE, repair bad instr after INST3 - William W. Plummer, 7/1/91
; Modified to use COM1 thru COM4 - William W. Plummer, 2/21/91
; Eliminate (incomplete) support for DOS1 - William W. Plummer, 11/13/90

; Changes may be copied and modified with no notice.  Copyrights and copylefts
; are consider silly and do not apply.	--  William W. Plummer

; modified to use MSC calling sequence.  jrr 3/86
;****************************************************************************
; Communications Package for the IBM PC, XT, AT and strict compatibles.
; May be copied and used freely -- This is a public domain program
; Developed by Richard Gillmann, John Romkey, Jerry Saltzer,
; Craig Milo Rogers, Dave Mitton and Larry Afrin.
;
; We'd sure like to see any improvements you might make.
; Please send all comments and queries about this package
; to [e-mail]
;
; o Supports both serial ports simultaneously
; o All speeds to 19200 baud
; o Compatible with PC, XT, AT
; o Built in XON/XOFF flow control option
; o C language calling conventions
; o Logs all comm errors
; o Direct connect or modem protocol
	PAGE;
;
; Buffer sizes -- *** MUST be powers of 2 ****

IFDEF UUPC
	R_SIZE	EQU	4096
	S_SIZE	EQU	4096
ENDIF

; If not set above, maybe on assembler command line.  But if not, ...
IFNDEF R_SIZE
	R_SIZE	EQU	512	; Recv buffer size
ENDIF
IFNDEF S_SIZE
	S_SIZE	EQU	512	; Send buffer size
ENDIF

; INTERRUPT NUMBERS
INT_COM1 EQU	0CH		; COM1: FROM 8259
INT_COM2 EQU	0BH		; COM2: FROM 8259
INT_COM3 EQU	0CH		; COM3: FROM 8259
INT_COM4 EQU	0BH		; COM4: FROM 8259
; 8259 PORTS
INTA00	EQU	20H		; 8259A PORT, A0 = 0
INTA01	EQU	21H		; 8259A PORT, A0 = 1
; COM1: & COM3: LEVEL 4
IRQ4	EQU	2*2*2*2 	; 8259A OCW1 MASK, M4=1, A0=0
NIRQ4	EQU	NOT IRQ4 AND 0FFH ; COMPLEMENT OF ABOVE
EOI4	EQU	4 OR 01100000B	; 8259A OCW2 SPECIFIC IRQ4 EOI, A0=0
; COM2: & COM4: LEVEL 3
IRQ3	EQU	2*2*2		; 8259A OCW1 MASK, M3=1, A0=0
NIRQ3	EQU	NOT IRQ3 AND 0FFH ; COMPLEMENT OF ABOVE
EOI3	EQU	3 OR 01100000B	; 8259A OCW2 SPECIFIC IRQ3 EOI, A0=0

; FLOW CONTROL CHARACTERS
CONTROL_Q EQU	11H		; XON
CONTROL_S EQU	13H		; XOFF
; MISC.
DOS	EQU	21H		; DOS FUNCTION CALLS

;
; ROM BIOS Data Area
;
RBDA	SEGMENT AT 40H
RS232_BASE DW	4 DUP(?)	; ADDRESSES OF RS232 ADAPTERS
RBDA	ENDS

PAGE;
;
; TABLE FOR EACH SERIAL PORT
;
SP_TAB		STRUC
PORT		DB	?	; 1 OR 2 OR 3 OR 4
; PARAMETERS FOR THIS INTERRUPT LEVEL
INT_COM 	DB	?	; INTERRUPT NUMBER
IRQ		DB	?	; 8259A OCW1 MASK
NIRQ		DB	?	; COMPLEMENT OF ABOVE
EOI		DB	?	; 8259A OCW2 SPECIFIC END OF INTERRUPT
; INTERRUPT HANDLERS FOR THIS LEVEL
INT_HNDLR	DW	?	; OFFSET TO INTERRUPT HANDLER
OLD_COM_OFF	DW	?	; OLD HANDLER'S OFFSET
OLD_COM_SEG	DW	?	; OLD HANDLER'S SEGMENT
; ATTRIBUTES
INSTALLED	DB	?	; IS PORT INSTALLED ON THIS PC? (1=YES,0=NO)
BAUD_RATE	DW	?	; 19200 MAX
CONNECTION	DB	?	; M(ODEM), D(IRECT)
PARITY		DB	?	; N(ONE), O(DD), E(VEN), S(PACE), M(ARK)
STOP_BITS	DB	?	; 1, 2
XON_XOFF	DB	?	; E(NABLED), D(ISABLED)
; FLOW CONTROL STATE
HOST_OFF	DB	?	; HOST XOFF'ED (1=YES,0=NO)
PC_OFF		DB	?	; PC XOFF'ED (1=YES,0=NO)
URGENT_SEND	DB	?	; We MUST send one byte (XON/XOFF)
SEND_OK 	DB	?	; DSR and CTS are ON
; ERROR COUNTS
ERROR_BLOCK	DW	8 DUP(?); EIGHT ERROR COUNTERS

; UART PORTS - DATREG thru MSR must be in order shown.
DATREG		DW	?	; DATA REGISTER
IER		DW	?	; INTERRUPT ENABLE REGISTER
IIR		DW	?	; INTERRUPT IDENTIFICATION REGISTER (RO)
LCR		DW	?	; LINE CONTROL REGISTER
MCR		DW	?	; MODEM CONTROL REGISTER
LSR		DW	?	; LINE STATUS REGISTER
MSR		DW	?	; MODEM STATUS REGISTER
UART_SILO_LEN	DB	?	; Size of a silo chunk (1 for 8250)
;
; BUFFER POINTERS
START_TDATA	DW	?	; INDEX TO FIRST CHARACTER IN X-MIT BUFFER
END_TDATA	DW	?	; INDEX TO FIRST FREE SPACE IN X-MIT BUFFER
START_RDATA	DW	?	; INDEX TO FIRST CHARACTER IN REC. BUFFER
END_RDATA	DW	?	; INDEX TO FIRST FREE SPACE IN REC. BUFFER
; BUFFER COUNTS
SIZE_TDATA	DW	?	; NUMBER OF CHARACTERS IN X-MIT BUFFER
SIZE_RDATA	DW	?	; NUMBER OF CHARACTERS IN REC. BUFFER
; BUFFERS
TBuff		DD	?	; Pointer to transmit buffer
RBuff		DD	?	; Pointer to receive buffer
SP_TAB		ENDS

; SP_TAB EQUATES
; WE HAVE TO USE THESE BECAUSE OF PROBLEMS WITH STRUC
EOVFLOW  EQU	ERROR_BLOCK	; BUFFER OVERFLOWS
EOVRUN		EQU	ERROR_BLOCK+2	; RECEIVE OVERRUNS
EBREAK		EQU	ERROR_BLOCK+4	; BREAK CHARS
EFRAME		EQU	ERROR_BLOCK+6	; FRAMING ERRORS
EPARITY  EQU	ERROR_BLOCK+8		; PARITY ERRORS
EXMIT		EQU	ERROR_BLOCK+10	; TRANSMISSION ERRORS
EDSR		EQU	ERROR_BLOCK+12	; DATA SET READY ERRORS
ECTS		EQU	ERROR_BLOCK+14	; CLEAR TO SEND ERRORS
DLL		EQU	DATREG		; LOW DIVISOR LATCH
DLH		EQU	IER		; HIGH DIVISOR LATCH

;
; Equates having to do with the FIFO
;
FCR		EQU	IIR	; FIFO Control Register (WO)
 ; Bits in FCR for NS16550A UART.  Note that writes to FCR are ignored
 ; by other chips.
 FIFO_ENABLE	EQU	001H	; Enable FIFO mode
 FIFO_CLR_RCV	EQU	002H	; Clear receive FIFO
 FIFO_CLR_XMT	EQU	004H	; Clear transmit FIFO
 FIFO_STR_DMA	EQU	008H	; Start DMA Mode
 ; 10H and 20H bits are register bank select on some UARTs (not handled)
 FIFO_SZ_4	EQU	040H	; Warning level is 4 before end
 FIFO_SZ_8	EQU	080H	; Warning level is 8 before end
 FIFO_SZ_14	EQU	0C0H	; Warning level is 14 before end
 ;
 ; Commands used in code to operate FIFO.  Made up as combinations of above
 ;
 FIFO_CLEAR	EQU	0	; Turn off FIFO
 FIFO_SETUP	EQU	FIFO_SZ_8 OR FIFO_ENABLE
 FIFO_INIT	EQU	FIFO_SETUP OR FIFO_CLR_RCV OR FIFO_CLR_XMT
 ;
 ; Miscellaneous FIFO-related stuff
 ;
FIFO_ENABLED	EQU	0C0H	; 16550 makes these equal FIFO_ENABLE
FIFO_LEN	EQU	8	; Length of the transmit FIFO in a 16550A
	PAGE;
;	put the data in the DGROUP segment
;	far calls enter with DS pointing to DGROUP
;
DGROUP	GROUP _DATA
_DATA	SEGMENT PUBLIC 'DATA'
;
DIV50		DW	2304	; ACTUAL DIVISOR FOR 50 BAUD IN USE
CURRENT_AREA	DW	AREA1	; CURRENTLY SELECTED AREA
; DATA AREAS FOR EACH PORT
AREA1	SP_TAB	<1,INT_COM1,IRQ4,NIRQ4,EOI4>	; COM1 DATA AREA
AREA2	SP_TAB	<2,INT_COM2,IRQ3,NIRQ3,EOI3>	; COM2 DATA AREA
AREA3	SP_TAB	<3,INT_COM3,IRQ4,NIRQ4,EOI4>	; COM3 DATA AREA
AREA4	SP_TAB	<4,INT_COM4,IRQ3,NIRQ3,EOI3>	; COM4 DATA AREA

IFDEF DEBUG
 ST8250:	DB "8250$"
 ST16550:	DB "16550$"
 STUART:	DB " UART detected", 0DH, 0AH, '$'
ENDIF

_DATA	ENDS




COM_TEXT SEGMENT PARA PUBLIC 'CODE'
	 ASSUME CS:COM_TEXT,DS:DGROUP,ES:NOTHING

	 PUBLIC AREA1, AREA2, AREA3, AREA4
	 PUBLIC _select_port
	 PUBLIC _save_com
	 PUBLIC _install_com
	 PUBLIC _restore_com
	 PUBLIC _open_com
	 PUBLIC _ioctl_com
	 PUBLIC _close_com
	 PUBLIC _dtr_on
	 PUBLIC _dtr_off
	 PUBLIC _r_count
	 PUBLIC _s_count
	 PUBLIC _receive_com
	 PUBLIC _send_com
	 PUBLIC _sendi_com
IFNDEF UUPC
	 PUBLIC _send_local
ENDIF
	 PUBLIC _break_com
	 PUBLIC _com_errors
	 PUBLIC _modem_status
IFDEF DEBUG
	 PUBLIC INST2, INST4
	 PUBLIC OPEN1, OPEN2, OPENX
	 PUBLIC DTRON1, DTRON6, DTRONF, DTRONS, DTRONX
	 PUBLIC RECV1, RECV3, RECV4, RECVX
	 PUBLIC SEND1, SENDX
	 PUBLIC WaitN, WaitN1, WaitN2
	 PUBLIC SENDII, SENDII2, SENDII4, SENDIIX
	 PUBLIC SPINLOOP
	 PUBLIC CHROUT, CHROUX
	 PUBLIC BREAKX
	 PUBLIC INT_HNDLR1, INT_HNDLR2, INT_HNDLR3, INT_HNDLR4
	 PUBLIC INT_COMMON, REPOLL, INT_END
	 PUBLIC LSI
	 PUBLIC MSI
	 PUBLIC TXI, TXI1, TXI2, TXI3, TXI9
	 PUBLIC TX_CHR
	 PUBLIC RXI, RXI0, RXI1, RXI2, RXI6, RXIX
ENDIF
	PAGE;
; Notes, thoughts and explainations by Bill Plummer.  These are intended to
; help those of you who would like to make modifications.

; Here's the order of calls in UUPC.  The routines in COMM.ASM are called
; from ulib.c.

; First (when a line in system has been read?), ulib&openline calls
;	 select_port()		; Sets up CURRENT_AREA
; then,  save_com()		; Save INT vector
; then,  install_com()		; Init area, hook INT
; then,  open_com(&cmd, 'D', 'N', STOP*T, 'D')  ; Init UART, clr bufs
; then,  dtr_on().

; At that point the line is up and running.  UUPC calls ulib&sread()
; which calls,	receive_com();

; And UUPC calls ulib&swrite()
; which calls,	send_com();

; To cause an error that the receiver will see, UUPC calls ulib&ssendbrk();
; which calls,	break_com();

; When all done with the line, UUPC calls ulib&closeline()
; which calls,	dtr_off();
; then,  close_com();
; then,  restore_com(); 	; Unhook INT
; and,	 stat_errors();


; Note: On the PC COM1 and COM3 share IRQ4, while COM2 and COM4 share IRQ3.
; BUT, only one device on a given IRQ line can be active at a time.  So it is
; sufficient for UUPC to hook whatever IRQ INT its modem is on as long as it
; unhooks it when it is done with that COM port.  COMM cannot be an installed
; device driver since it must go away when UUPC is done so that other devices
; on the same INTs will come back to life.  Also, it is OK to have a static
; CURRENT_AREA containing the current area that UUPC is using.

; Note about using the NS16550A UART chip's FIFOs.  These are operated as
; silos.  In other words when an interrupt happens because the receive(send)
; FIFO is nearly full(empty), as many bytes as possible are transferred and
; the interrupt dismissed.  Thus, the interrupt load is lowered.


; Concerning the way the comm line is brought up.
; There are two basic cases, the Direct ('D') connection and the Modem ('M')
; connection.  For either UUPC calls dtr_on_com() to bring up the line.  This
; causes Data Terminal Ready (DTR) and Request To Send (RTS) to be set.  Note
; this is OK for a simple 3-wire link but may be REQUIRED for a COM port
; connected to an external modem.

; The difference between a D connection and an M connection is
; whether or not the PC can expect any signals back from the modem.  If
; there is a simple 3-wire link, Data Set Ready will be floating.
; (Actually, some wise people jumper Data Terminal Read back to Data
; Set Ready so the PC sees its own DTR appear as DSR.)	UUPC should be
; able to handle the simplest cable as a design feature.  So both D and
; M connections send out DTR and RTS, but only the M connection expects
; a modem to respond.

; Then, if it is full modem connection (M), we wait for a few
; seconds hoping that both Data Set Ready (DSR) and Clear To Send (CTS)
; will come up.  If they don't, the associated counters are incremented
; for subsequent printing in the error log.  Note that no error is
; reported from COMM to UUPC at this point, although this would be a
; good idea.  COMMFIFO.ASM forces the connection to be a D type and lets
; UUPC storm ahead with its output trying to
; establish a link, but the output is never sent due to one of the
; control signals being false.	UUPC could check the modem status using
; a call which has been installed just for this purpose.

; Note, if you are going to connect your PC running UUPC to,
; say, a mainframe and you need hardware flow control (i.e., RTS-CTS
; handshaking), use a Modem connection.  Using a simple 3-wire cable
; forbids hardware flow control and UUPC must be instructed to use a
; Direct connection.  Refer to comments in the SYSTEMS file on how to
; make this selection.

; References used in designing the revisions to COMM.ASM:
;	1.	The UNIX fas.c Driver code.
;	2.	SLIP8250.ASM from the Clarkson driver set.
;	3.	NS16550A data sheet and AN-491 from National Semiconductor.
;	4.	Bell System Data Communications, Technical Reference for
;		Data Set 103A, Interface Specification, February, 1967
;	5.	Network mail regarding V.24
;	6.	Joe Doupnik
	PAGE;
;
; void far select_port(int)
;	Arg is 1..4 and specifies which COM port is referenced by
;	all other calls in this package.
;
_select_port PROC FAR
	push bp
	mov bp,sp
	mov AX,[bp+6]			; get aguement
	CMP	AL,1			; Port 1?
	 JE	SP1			; Yes
	CMP	AL,2			; Port 2?
	 JE	SP2			; Yes
	CMP	AL,3			; Port 3?
	 JE	SP3			; Yes
	CMP	AL,4			; Port 4?
	 JE	SP4			; Yes
	INT 20H 			; N.O.T.A. ????? Halt for debugging!
	; Assume port 1 if continued
SP1:	MOV	AX,OFFSET DGROUP:AREA1	; SELECT COM1 DATA AREA
	JMP	SHORT SPX		; CONTINUE
SP2:	MOV	AX,OFFSET DGROUP:AREA2	; SELECT COM2 DATA AREA
	JMP	SHORT SPX		; CONTINUE
SP3:	MOV	AX,OFFSET DGROUP:AREA3	; SELECT COM3 DATA AREA
	JMP	SHORT SPX		; CONTINUE
SP4:	MOV	AX,OFFSET DGROUP:AREA4	; SELECT COM4 DATA AREA
	;Fall into SPX
SPX:	MOV	CURRENT_AREA,AX 	; SET SELECTION IN MEMORY
	mov sp,bp