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Simtel MSDOS 1992 September
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Simtel20_Sept92.cdr
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sysutl
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async_ce.arc
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ASYNC.ASM
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Assembly Source File
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1987-08-31
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48KB
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1,336 lines
page 58,132
; file: ASYNC.ASM
TITLE ASYNC DRIVER FOR MSDOS
SUBTTL DESCRIPTION
;
; Loadable asyncrounous device driver for msdos.
; Written by: Mike Higgins
; Copyright (c) April 1984 by The Computer Entomologist.
;
; Permission is hearby granted to use or distribute this software
;without any restrictions. You may make copies for yourself or your
;friends. You may include it in any hardware or software product that you
;sell for profit.
;
; This software is distributed as is, and is not guaranteed to work
;on any particular hardware/software configuration. Furthermore, no
;liability is granted with this software: the user takes responcibility for
;any damage this software may do to his system.
;
; Nasy notices aside, if you have any questions about this software, you
;can reach me at the address below. If you impliment any new features or
;find (and fix!) any bugs, I would be happy to hear from you.
;
; Mike Higgins
; The Computer Entomologist
; P.O. Box 197
; Duncans Mills, CA 95430
;
; -Impliments FULL RS232 support for IBM PC and compatable async cards.
; -Includes 128-byte buffers on input and output.
; -Supports Xon/Xoff or hardware handshake. Hardware handshake uses
; DSR or CTS (to throttle output data) All handshake modes are
; treated separately, an can be used in combinations.
; -Bells can be set to echo when the input buffer overflows.
; -An inteligent half-duplex mode is available that echoes characters
; only after MSDOS has requested them. (Typed-ahead answers to
; questions apear AFTER the questions, not as you type them).
; -The 8th bit (parity) can optionally be stripped off on input
; and/or output.
; -Lower case characters can optionally be translated to upper case
; on input and/or output.
; -Control-c and control-s characters are optionally passed through
; the buffer on non-destructive reads so that the buffer does not
; defeat the break command to MSDOS when the buffer is full.
; -Several escape sequences are optionally scanned for on input that
; perform useful tasks when used as a console terminal:
; 1) A soft reset sequence that re-boots the system in the same way
; ALT-SHIFT-DEL does. (Default: control-C control-R control-B).
; 2) A flush input buffer sequence that removes all characters in
; the 128 byte typeahead buffer that have not been read by
; MSDOS yet (Default: control-X).
; 3) A re-draw the last output line sequence. (Default: control-R).
; 4) A delete line sequence that will delete all input back to the
; begening of the last line. (Default: control-U).
; 5) A skip output sequence turns this driver into a NUL device,
; (output data disapears) until the next skip-output sequence is
; types, or until input is requested. (Default: control-O).
; -The IOCTRL read and write function is used to query or change
; baud rates, bits/byte, parity, as well as enabling/disabling all
; the optional features mentioned above. This eliminates the
; necesity of a program that has special knowledge of the system.
; A program to change these features need not know the location of
; the driver or special words in low memory, or even the port
; address of the UART. Instead, all that is needed is the name of
; the device, and the format of an IOCTL write to this driver.
;
; ASSEMBLY INSTRUCTIONS:
; MASM ASYNC,ASYNC,ASYNC,NUL
; LINK ASYNC,ASYNC,ASYNC,NUL
; EXE2BIN ASYNC
; COPY ASYNC.BIN A: (IF NOT THERE ALREADY)
; ADD THE FOLLOWING LINE TO A:CONFIG.SYS:
; DRIVER=ASYNC.BIN
; RE-BOOT YOUR SYSTEM AND IT'S THERE! NOTE: THIS DRIVER
; DOES NOT GET ALONG AT ALL WITH BASICA OR MODE, AND POSSIBLY
; MANY OTHER PCDOS PROGRAMS THAT DO NOT CONFORM TO THE MSDOS
; STANDARDS. BASICA IN PARTICULAR MUCKS UP ALL THE ASYNC CARD
; INTERNAL REGESTERS, REDIRECTS THE HARDWARE VECTOR, AND IT
; NEVER PUTS THEM BACK THE WAY THEY WERE. IF YOU TRY TO USE
; THIS DRIVER AFTER BASICA HAS BEEN IN MEMORY, THE DRIVER WILL
; PROBABLY HANG YOUR SYSTEM.
;
; ***BUGS***
;
; If your RS232 device continually sends data to the driver, the driver
; will hang when your system boots. (The EPSON RX80 serial card sends
; ^Q's constantly and causes this). The current solution is to leave
; your device turned off until the system boots completely. Then turn
; the RS232 device on after the driver is ready for it, and everything
; works as expected.
;
; There are a lot of hooks in the driver for features that do not work
; yet. (For example, input data throttleing, output conversion of
; tabs to spaces). So don't expect all of these things to work just
; because there are comments about them or bits to set for them.
; Write me if you do impliment any of this stuff.
SUBTTL DEFINITIONS
PAGE
;
; DEVICE TYPE CODES
DEVCHR EQU 08000h ;THIS IS A CHARACTER DEVICE
DEVBLK EQU 0H ;THIS IS A BLOCK (DISK) DEVICE
DEVIOC EQU 04000H ;THIS DEVICE ACCEPTS IOCTRL REQUESTS
DEVNON EQU 02000H ;NON IBM DISK DRIVER
DEVSPC EQU 010H ;CONSOLE ACCEPTS SPECIAL INTERUPT 29
DEVCLK EQU 08H ;THIS IS THE CLOCK DEVICE
DEVNUL EQU 04H ;THIS IS THE NUL DEVICE
DEVSTO EQU 02H ;THIS IS THE CURRENT STANDARD OUTPUT DEVICE
DEVSTI EQU 01H ;THIS IS THE STANDARD INPUT DEVICE
;
; ERROR STATUS BITS
STSERR EQU 08000H ;GENERAL ERROR, SEE LOWER ORDER BITS FOR REASON
STSBSY EQU 0200H ;DEVICE IS BUISY
STSDNE EQU 0100H ;REQUEST IS COMPLETED
; ERROR REASON VALUES FOR LOWER ORDER BITS.
ERRWP EQU 0 ;WRITE PROTECT ERROR
ERRUU EQU 1 ;UNKNOWN UNIT
ERRDNR EQU 2 ;DRIVE NOT READY
ERRUC EQU 3 ;UNKNOWN COMMAND
ERRCRC EQU 4 ;CYCLIC REDUNDANCY CHECK ERROR
ERRBSL EQU 5 ;BAD DRIVE REQUEST STRUCTURE LENGTH
ERRSL EQU 6 ;SEEK ERROR
ERRUM EQU 7 ;UNKNOWN MEDIA
ERRSNF EQU 8 ;SECTOR NOT FOUND
ERRPOP EQU 9 ;PRINTER OUT OF PAPER
ERRWF EQU 10 ;WRITE FAULT
ERRRF EQU 11 ;READ FAULT
ERRGF EQU 12 ;GENERAL FAILURE
;
; DEFINE THE BIT MEANINGS OF THE OUTPUT STATUS BYTE
;
LINIDL EQU 0FFH ;IF ALL BITS OFF, XMITTER IS IDLE.
LINXOF EQU 1 ;OUTPUT IS SUSPENDED BY XOFF
LINEXP EQU 2 ;XMITTER IS BUISY, INTERUPT EXPECTED.
LINSKP EQU 8 ;SKIP OUTPUT UNTIL NEXT SKIPO SEQUENC.
LINDSR EQU 10H ;OUTPUT IS SUSPENDED UNTIL DSR COMES ON AGAIN
LINCTS EQU 20H ;OUTPUT IS SUSPENDED UNTIL CTS COMES ON AGAIN
;
; BIT DEFINITIONS OF THE INPUT STATUS BYTE
;
MODERR EQU 1 ;INPUT LINE ERRORS HAVE BEEN DETECTED.
MODOVR EQU 4 ;RECEIVER BUFFER OVERFLOWED, DATA LOST.
MODOFF EQU 2 ;DEVICE IS OFFLINE NOW.
;
; DEFINE THE BIT MEANINGS IN THE SPECIAL CHARACTERISTICS WORDS
;
; THE FIRST SPECIAL WORD CONTROLS HOW THE INPUT FROM THE UART IS TREATED
;
INDTR EQU 2 ;DTR IS DATA-THROTTLE SIGNAL.
INRTS EQU 4 ;RTS IS DATA-THROTTLE SIGNAL.
INXON EQU 8 ;XON/XOFF IS USED TO THROTTLE INPUT DATA.
INBEL EQU 010H ;BELLS ARE ECHOED WHEN BUFFER OVERFLOWS.
INHDP EQU 020H ;HALF DUPLEX: INPUT CHARS ARE ECHOED.
INCTX EQU 040H ;FLUSH INPUT BUFFER SEQUENCE RECOGNIZED.
INCTR EQU 080H ;RE-DRAW CURRENT LINE ENABLED.
INCTU EQU 0100H ;DELETE CURRENT LINE ENABLED.
INCTO EQU 0200H ;SKIP OUTPUT SEQUENCE INABLED.
INEST EQU 0400H ;ERRORS CAUSE STATUS RETURNS.
INEPC EQU 0800H ;ERRORS TRANSLATE TO CODES WITH PARITY BIT ON.
INSTP EQU 01000H ;STRIP PARITY BIT OFF ON INPUT
INUPR EQU 02000H ;FORCE CHARACTERS TO UPPER CASE.
INCTC EQU 04000H ;CONTROL-C LEAPS INPUT BUFFER ON N.D. READ.
INRES EQU 08000H ;RESET SEQUENCE CAUSES SYSTEM RE-BOOT.
;
; THE SECOND SPECIAL WORD CONTROLS HOW THE OUTPUT TO THE UART IS TREATED
;
OUTDSR EQU 2 ;DSR IS USED TO THROTTLE OUTPUT DATA.
OUTCTS EQU 4 ;CTS IS USED TO THROTTLE OUTPUT DATA.
OUTXON EQU 8 ;XON/XOFF IS USED TO THROTTLE OUTPUT DATA.
OUTCSF EQU 010H ;CTS IS OFFLINE SIGNAL.
OUTCDF EQU 020H ;CARRIER DETECT IS OFFLINE SIGNAL
OUTDRF EQU 040H ;DSR IS OFFLINE SIGNAL.
OUTSTP EQU 01000H ;STRIP PARITY OFF ON OUTPUT.
OUTUPR EQU 02000H ;LOWER CASE XLATES TO UPPER ON OUTPUT.
OUTTAB EQU 04000H ;TABS ARE TRANSLATED TO SPACES ON OUTPUT.
;
; DEFINE THE PORT OFFSETS AND IMPORTANT ASYNC BOARD CONSTANTS
DLAB EQU 080H ;DIVISOR LATCH ACCESS BIT
ALLINT EQU 01111B ;ENABLE ALL INTERUPTS IN INTEN REGESTER.
TXBUF EQU 0 ;OFFSET TO TRANSMITTER BUFFER REGESTER
RXBUF EQU 0 ;DITO FOR RECEIVER (DIRECTION DIFERENTIATES FUNCS)
BAUD0 EQU 0 ;BAUD DIVISOR REG (DLAB IN LCTRL DIFFERENCIATES)
BAUD1 EQU 1 ;BAUD DIVISOR HIGH BYTE
INTEN EQU 1 ;INTERUPT ENABLE REGESTER
INTID EQU 2 ;INTERUPT IDENTIFICATION REGESTER.
LCTRL EQU 3 ;LINE CONTROL REGESTER
MCTRL EQU 4 ;MODEM CONTROL REGESTER
LSTAT EQU 5 ;LINE STATUS REGESTER
MSTAT EQU 6 ;MODEM STATUS REGESTER
BOOTS SEGMENT AT 0FFFFH ;SEGMENT FOR FAR JUMP TO WARM BOOT
RE_BOOT LABEL FAR ;ADDRESS. THIS IS USED BY THE
BOOTS ENDS ;RE-BOOT ESCAPE SEQUENCE, IF ENABLED.
VECS SEGMENT AT 0 ;ON AN IBM PC, YOU CAN REQUEST A "QUICK" BOOT
ORG 72H ;BY STORING 1234H IN LOCATION 0:72. THIS IS
FLAG LABEL WORD ;THE MOST IBM SPECIFIC THING IN THIS WHOLE
VECS ENDS ;DRIVER, YOU MAY HAVE TO CHANGE THE RE-BOOT
;LOGIC FOR OTHER SYSTEMS. ON THE OTHER HAND,
;WRITING TO 0:72 BEFORE RESETTING THE 8088
;CAN'T DO ANY HARM, SO YOU CAN LEAVE THIS IN.
SUBTTL DRIVER LIST HEAD
PAGE
;*************************************************************************
;
; BEGENING OF DRIVER CODE.
;
DRIVER SEGMENT
ASSUME CS:DRIVER,DS:DRIVER,ES:DRIVER
; ORG 0 ;DRIVERS START AT 0
ASYNC2:
DW ASYNC1,-1 ;POINTER TO NEXT DEVICE: DOS FILLS THIS IN.
DW DEVCHR OR DEVIOC ;CHARACTER DEVICE
DW STRATEGY ;OFFSET TO STRATEGY ROUTINE.
DW REQUEST2 ;OFFSET TO "INTERUPT" ENTRYPOINT.
DB "ASYNC2 " ;DEVICE NAME.
ASYNC1:
DW -1,-1 ;POINTER TO NEXT DEVICE: END OF LINKED LIST.
DW DEVCHR OR DEVIOC ;THIS DEVICE IS CHARACTER IOCTL
DW STRATEGY ;STRATEGY ROUTINE
DW REQUEST1 ;I/O REQUEST ROUTINT
DB "ASYNC1 "
debug dd 0b8000000h
onotify macro char
push es
push di
push ax
mov ax,'&char'
les di,CS:debug
stos byte ptr [di]
inc di
mov word ptr CS:debug,di
pop ax
pop di
pop es
endm
SUBTTL DRIVER INTERNAL DATA STRUCTURES
PAGE
;
ASY_UNITS EQU 2 ;NUMBER OF UNITS THIS DRIVER IS BUILT FOR
UNIT STRUC ;EACH UNIT HAS A STRUCTURE DEFINING IT'S STATE:
PORT DW ? ;I/O PORT ADDRESS
VECT DW ? ;INTERUPT VECTOR OFFSET (NOT INTERUPT NUMBER!)
ISRADR DW ? ;OFFSET TO INTERUPT SERVICE ROUTINE
LINE DB ? ;DEFAULT LINE CONTROL BIT SETTINGS DURING INIT,
;OUTPUT STATUS BITS AFTERWORDS.
MODEM DB ? ;MODEM CONTROL BIT SETTINGS DURING INIT,
;INPUT STATUS BITS AFTERWARDS.
INSPEC DW ? ;SPECIAL CHAR INPUT TREATMENT, HANDSHAKING MODE.
OUTSPEC DW ? ;SPECIAL MODE BITS FOR OUTPUT
BAUD DW ? ;CURRENT BAUD RATE DIVISOR VALUE
FLSHP DW ? ;OFFSET INTO FLUSH BUFFER COMMAND STRING.
REDRP DW ? ;OFFSET INTO RE-DRAW LINE COMMAND STRING.
BACKP DW ? ;OFFSET INTO DELETE CURRENT LINE COMMAND STRING.
SKIPP DW ? ;OFFSET INTO SKIP OUTPUT SEQUENCE.
REBTP DW ? ;OFFSET INTO RE-BOOT SYSTEM COMMAND STRING.
IFIRST DW ? ;OFFSET TO FIRST CHARACTER IN INPUT BUFFER.
IAVAIL DW ? ;OFFSET TO NEXT AVAILABLE BYTE.
IBUF DW ? ;POINTER TO 128 BYTE INPUT BUFFER.
OFIRST DW ? ;OFFSET INTO FIRST CHARACTER IN OUTPUT BUFFER
OAVAIL DW ? ;OFFSET INTO NEXT AVAIL BYTE IN OUTPUT BUFFER
OBUF DW ? ;POINTER TO 128 BYTE OUTPUT BUFFER
UNIT ENDS
;TABLE OF STRUCTURES FOR EACH ASYNCROUNOUS UNIT
;ASYNC1 DEFAULTS TO THE COM1 PORT AND VECTOR,
;NO PARITY, 8 DATA BITS, 1 STOP BIT,AND 9600 BAUD.
ASY_TAB1:
UNIT <3F8H,30H,ASY1ISR,3,0BH,0D3D0H,8,12,0,0,0,0,0,0,0,IN1BUF,0,0,OUT1BUF>
;ASYNC2 DEFAULTS TO THE COM2 PORT AND VECTOR,
;NO PARITY, 8 DATA BITS, 1 STOP BIT,
;AND 9600 BAUD.
ASY_TAB2:
UNIT <2F8H,2CH,ASY2ISR,3,0BH,0D3D0H,8,12,0,0,0,0,0,0,0,IN2BUF,0,0,OUT2BUF>
;IF THE BUFFER SIZE IS A POWER OF TWO, THE PROCESS OF KEEPING
;THE OFSETTS WITHIN THE BOUNDS OF THE BUFFER IS GREATLY
;SIMPLIFIED. IF YOU MODIFY THE BUFFER SIZE, KEEP IT A
;POWER OF 2, AND MODIFY THE MASK ACCORDINGLY.
BUFSIZ EQU 128 ;INPUT BUFFER SIZE
BUFMSK EQU 127 ;MASK FOR CALCULATING OFFSETS MODULO BUFSIZ
IN1BUF DB BUFSIZ DUP (?)
IN2BUF DB BUFSIZ DUP (?)
OUT1BUF DB BUFSIZ DUP (?)
OUT2BUF DB BUFSIZ DUP (?)
;
; BAUD RATE CONVERSION TABLE
ASY_BAUDT DW 50,2304 ;FIRST VALUE IS DESIRED BAUD RATE,
DW 75,1536 ;SECOND IS DIVISOR REGISTER VALUE.
DW 110,1047
DW 134,857
DW 150,786
DW 300,384
DW 600,192
DW 1200,96
DW 1800,64
DW 2000,58
DW 2400,48
DW 3600,32
DW 4800,24
DW 7200,16
DW 9600,12
;
; DEFINE THE SEQUENCES OF CHARACTERS THAT ARE SCANNED FOR ON
; INPUT, USED TO FLUSH BUFFER, RE-BOOT, RE-DRAW LINES, ETC.
; EACH OF THESE SEQUENCES IS A STRING OF THREE OR LESS
; BYTES TERMINATED WITH A NUL. HERE THEY ARE PADDED WITH NULS
; TO 4 BYTES EACH SO THAT ALTERNATE SEQUENCES CAN BE PATCHED IN
; WITH DEBUG.
;
FLUSH DB 'X' AND 1FH,0,0,0 ;FLUSH INPUT BUFFER
REDRAW DB 'R' AND 1FH,0,0,0 ;RE-DRAW LAST LINE
BACKL DB 'U' AND 1FH,0,0,0 ;DELETE LAST LINE
SKIPO DB 'O' AND 1FH,0,0,0 ;SKIP OUTPUT
REBOOT DB 'C' AND 1FH,'R' AND 1FH,'B' AND 1FH,0 ;RE-BOOT SYSTEM
;
; STRUCTURE OF AN I/O REQUEST PACKET STATIC HEADER
;
PACK STRUC
LEN DB ? ;LENGTH OF RECORD
PRTNO DB ? ;UNIT CODE
CODE DB ? ;COMMAND CODE
STAT DW ? ;RETURN STATUS
DOSQ DD ? ;UNUSED DOS QUE LINK POINTER
DEVQ DD ? ;UNUSED DRIVER QUE LINK POINTER
MEDIA DB ? ;MEDIA CODE ON READ/WRITE
XFER DW ? ;XFER ADDRESS OFFSET
XSEG DW ? ;XFER ADDRESS SEGMENT
COUNT DW ? ;TRANSFER BYTE COUNT.
PACK ENDS
;
; THE FOLLOWING TWO WORDS IS THE STORAGE AREA FOR THE REQUEST PACKET
; ADDRESS, SENT TO ME BY A STRATEGY ROUTINE CALL.
; AS REQUESTED BY THE MSDOS DRIVER MANUAL, I AM "THINKING
; ABOUT" THE FUTURE, SO I`M DESIGNATING THIS POINTER AS THE QUEUE
; LIST HEAD FOR REQUESTS TO THIS DRIVER.
;
PACKHEAD DD 0
;
; THE STRATEGY ROUTINE ITSELF.
STRATEGY PROC FAR
;SQUIRREL AWAY THE POINTER FOR LATER.
MOV WORD PTR CS:PACKHEAD,BX ;STORE THE OFFSET,
MOV WORD PTR CS:PACKHEAD+2,ES ;AND THE SEGMENT.
RET
STRATEGY ENDP
SUBTTL REQUEST ROUTINES
PAGE
; PHYLOSOPHICAL RUMINATIONS:
; Why does MicroSoft INSIST on choosing names for things that
; already have firmly defined meanings for OTHER things? Take for
; example, the MASM definition of a SEGMENT: It bears little relation
; to the deffinition of a segment in the intel 8088 processor handbook.
; This leads to a GREAT DEAL of confusion. Many other assemblers on
; other systems have constructs that are equivalent to MASM's SEGMENT,
; they are often called PSECTS for Program SECTionS. Perhaps the
; people at Microsoft wanted a word that made more sence in English,
; but I wish they had chosen SECTION instead of SEGMENT.
; The example that it bringing all this to mind now is the
; MicroSoft device driver documentation, which insists on calling
; the following routine an "interupt routine". Go read the intel
; manual, you will find that an interupt routine is defined THERE as
; a bunch of code that is jumped to by a special kind of event in
; the hardware. That is NOT what the people at MicroSquishy mean
; this time either. Depending on weather you describe these routines
; in terms of what they do now, or in the "future", the following
; routine should be called the "I/O request routine" or the "I/O
; completion routine". But NO, they had to deside to call this
; the "interupt routine", and create another layer of confusion for
; those of us who already know the traditional deffinition of this
; relatively well known phrase.
;
; I am herby refering to the "interupt routine" as the
; "request routine", and nameing all my labels accordingly.
;
; I/O REQUEST ROUTINES
REQUEST1: ;ASYNC1 HAS BEEN REQUESTED
PUSH SI ;SAVE SI SO YOU CAN
MOV SI,OFFSET ASY_TAB1 ;GET THE DEVICE UNIT TABLE ADDRESS.
JMP GEN_REQUEST ;THE GENERIC DRIVER DOES THE REST.
REQUEST2: ;ASYNC2 HAS BEEN REQUESTED TO DO SOMETHING
PUSH SI ;SAVE SI
MOV SI,OFFSET ASY_TAB2 ;GET UNIT TABLE TWO`S ADDRESS
GEN_REQUEST:
PUSHF ;I REQUIRE DIRECTION FLAG CLEARED, SO I SAVE
CLD ;THE FLAGS AND CLEAR THEM HERE.
PUSH AX ;SAVE ALL THE REGESTERS, YOU MAY NOT
PUSH BX ;NEED THEM ALL, BUT YOU WILL REGRET IT
PUSH CX ;IF YOU FORGET TO SAVE JUST ONE OF THEM.
PUSH DX
PUSH DI
PUSH BP
PUSH DS
PUSH ES
PUSH CS ;COPY THE CS REGESTER
POP DS ;INTO THE DS TO ACCESS MY DATA
LES BX,PACKHEAD ;RECOVER THE POINTER TO THE PACKET.
MOV DI,OFFSET ASY_FUNCS ;GET THE POINTER TO THE DISPATCH TABLE
MOV AL,ES:CODE[BX] ;GET THE FUNCTION REQUEST CODE,
MOV AH,0 ;MAKE IT INTO A WORD,
SAL AX,1 ;CONVERT TO A WORD OFFSET,
ADD DI,AX ;AND ADD TO THE TABLE START ADDRESS
JMP [DI] ;JUMP TO THE APPROPRIATE ROUTINE
;
; TABLE OF OFFSETS TO ALL THE DRIVER FUNCTIONS
ASY_FUNCS:
DW ASYNC_INIT ;INITIALIZE DRIVER
DW EXIT ;MEDIA CHECK (BLOCK DEVICES ONLY)
DW EXIT ;BUILD BPB (BLOCK DEVICES ONLY)
DW IOCTLIN ;IOCTL INPUT
DW READ ;READ
DW NDREAD ;NON-DESTRUCTIVE READ
DW RXSTAT ;INPUT STATUS
DW INFLUSH ;FLUSH INPUT BUFFER
DW WRITE ;WRITE
DW WRITE ;WRITE WITH VERIFY
DW TXSTAT ;OUTPUT STATUS
DW TXFLUSH ;FLUSH OUTPUT BUFFER
DW IOCTLOUT ;IOCTL OUTPUT
;
; EXIT FROM DRIVER REQUEST
; CALL WITH AX= RETURN STATUS VALUE
EXITP PROC FAR
EXIT:
LES BX,PACKHEAD ;RETREIVE POINTER TO PACKET
OR AX,STSDNE ;SET THE DONE BIT IN IT.
MOV ES:STAT[BX],AX ;STORE THE STATUS BACK IN THE PACKET.
POP ES ;RESTORE ALL THE REGESTERS
POP DS
POP BP
POP DI
POP DX
POP CX
POP BX
POP AX
POPF
POP SI
RET
EXITP ENDP
SUBTTL READ DATA REQUEST ROUTINE
PAGE
;
; ALL THE FOLLOWING ROUTINES ARE CALLED WITH THE SAME CONTEXT
; FROM THE REQUEST ROUTINE:
; - ES:BX POINTS TO THE I/O PACKET.
; ROUTINES CAN MUCK UP THESE TWO REGESTERS IF THEY WANT, AS EXIT
; WILL RESTORE THEM BEFORE IT TRIES TO SEND THE STATUS WORD BACK.
; - CS: AND DS: POINT TO THE BEGENING OF THE DRIVER SEGMENT.
; - DS:SI POINTS TO THE DEVICE UNIT TABLE DESCRIBING THE PARTICULAR
; PORT BEING ACCESSED.
; - ALL OTHER REGESTERS ARE AVAILABLE FOR USE, THE EXIT ROUTINE
; RESTORES THEM ALL BEFORE RETURNING TO MSDOS.
; ALL THE FOLLOWING ROUTINES SHOULD EXIT BY DOING A JMP
; TO THE EXIT ROUTINE. EXIT ASSUMES THAT AX
; CONTAINS EITHER ZERO, OR THE ERROR BIT SET AND A VALID ERROR
; RETURN VALUE IN THE LOW ORDER BITS. EXIT SETS THE DONE BIT IN
; THIS VALUE FOR YOU BEFORE IT RETURNS TO MSDOS.
;
SUBTTL READ REQUEST ROUTINE
; READ DATA FROM DEVICE
;
READ:
MOV CX,ES:COUNT[BX] ;GET THE REQUESTED NUMBER OF BYTES
MOV DI,ES:XFER[BX] ;DI IS OFFSET TO USER BUFFER
MOV DX,ES:XSEG[BX] ;SEGMENT IS LAST I NEED FROM PACKET,
MOV ES,DX ;NOW ES:DI POINTS TO USER BUFFER.
TEST LINE[SI],LINSKP ;IF THERE IS A SKIP OUTPUT IN
JE NO_SKIP ;PROGRESS, I MUST CANCEL IT NOW.
AND LINE[SI],NOT LINSKP ;CLEAR THE SKIP OUTPUT BIT.
CALL START_OUTPUT ;START THE XMITTER GOING AGAIN.
NO_SKIP:
TEST MODEM[SI],MODERR OR MODOVR ;HAVE ANY LINE ERRORS OCCURED?
JE NO_LERR ;NOT LATELY.
AND MODEM[SI],NOT ( MODERR OR MODOVR ) ;YES, CLEAR THE BITS,
MOV AX,ERRRF ;AND RETURN ERROR INDICATION TO DOS
JMP EXIT
NO_LERR:
RLUP:
CALL GET_IN ;GET NEXT CHAR FROM INPUT BUFFER
CMP AH,0 ;WAS THERE ONE?
JE TEST_READ ;YES, TEST FOR SPECIAL BITS
JMP RLUP ;NO, WAIT FOR A CHAR TO ARRIVE.
TEST_READ:
;BEFORE RETURNING A CHARACTER TO MSDOS, I CHECK FOR ANY
;SPECIAL PROCESSING I AM REQUIRED TO DO. I DO AS MANY
;OF THESE FUNCTIONS HERE AS POSSIBLE, TO SAVE THE
;RECEIVER INTERUPT ROUTINE FROM HAVING TO DO THEM, AND
;TO ALLOW INTELIGENT USE OF THE RING BUFFER. FOR EXAMPLE,
;CHARACTERS TO NOT ECHO-HALF-DUPLEX UNTIL THEY ARE READ
;FROM THE BUFFER HERE, SO A PROGRAM THAT DISABLES ECHO
;WHILE READING A PASSWORD WILL WORK EVEN IF THE USER TYPED
;THE PASWORD IN BEFORE BEING PROMPTED FOR IT.
;************************************
;TEST FOR STRIPPING PARITY BIT
TEST INSPEC[SI],INSTP ;SHOULD I STRIP PARITY?
JE NO_STRIP ;NOPE.
AND AL,NOT 080H ;YES.
NO_STRIP:
;*********************************
;TEST FOR UPPER-CASE CONVERSION
TEST INSPEC[SI],INUPR ;IS LOWER TO UPPER CONV. ENABLED?
JE NO_UPPER ;NOPE, SKIP THIS.
MOV AH,AL ;MAKE A COPY IN AH,
AND AH,07FH ;STRIP PARITY TO MAKE TEST VALID,
CMP AH,'a' ;IS IT < A LOWER CASE a?
JL NO_UPPER ;YES, THEN IT'S NOT LOWER.
CMP AH,'z' ;IS IT > A LOWER CASE z?
JG NO_UPPER ;YES, THEN IT'S STILL NOT LOWER.
SUB AL,020H ;NO, THEN CONVERT THE ONE IN AL.
NO_UPPER:
;**********************************8
;TEST FOR HALF-DUPLEX MODE
STOS BYTE PTR [DI] ;BUT FIRST STORE CHAR IN USER BUFFER.
TEST INSPEC[SI],INHDP ;AM I IN HALF DUPLEX MODE?
JE NO_HALF ;NO.
HALF_WAIT:
CALL PUT_OUT ;YES, PUT THE CHARACTER IN OUTBUF.
CMP AH,0 ;WAS THERE ROOM?
JNE HALF_WAIT ;NO, WAIT FOR IT.
CALL START_OUTPUT ;AND MAKE SURE THE XMITTER STARTS
NO_HALF:
;ALTHOUGH MSDOS NEVER, TO MY KNOWLEDGE, ASKS FOR MORE THAN
;ONE STUPID CHARACTER AT A TIME, I LOOP ON THE REQUEST SIZE
;SO THAT THIS DRIVER WILL STILL WORK ON THAT GLORIOUS DAY
;WHEN SOMEBODY ASKS FOR MORE THAN ONE.
LOOP RLUP ;KEEP GOING IF YOU WERE REQUESTED.
MOV AL,0 ;RETURN NO ERRORS IN AX IF DONE.
JMP EXIT
SUBTTL NON-DESTRUCTIVE READ REQUEST ROUTINE
PAGE
; NON-DESTRUCTIVE READ FROM DEVICE
;
NDREAD:
MOV DI,IFIRST[SI] ;GET POINTER TO FIRST CHAR
CMP DI,IAVAIL[SI] ;IS THE BUFFER EMPTY?
JNE NDGET ;NO, GET ONE NON DESTRUCTIVELY.
MOV AX,STSBSY ;YES, RETURN DEVICE BUISY
JMP EXIT
NDGET:
PUSH BX ;SAVE AN EXTRA COPY OF BX.
MOV BX,IBUF[SI] ;GET BUFFER ADDRESS
TEST INSPEC[SI],INCTC ;SHOULD I CHECK FOR IMBEDDED ^C'S?
JE NONDCTC ;NO.
;YES, SCAN BUFFER FOR CONTROL-C.
CTCLUP:
CMP BYTE PTR [BX+DI],'C' AND 1FH ;IS THIS A CONTROL-C?
JNE NXTCTC ;NO, GO TRY AGAIN
YESCTC:
MOV IFIRST[SI],DI ;YES, DESTRUCTIVELY READ TO HERE,
JMP NONDCTC ;AND RETURN THE CONTROL-C.
NXTCTC:
CMP BYTE PTR [BX+DI],'S' AND 1FH ;DO THE SAME TEST FOR ^S
JE YESCTC ;IN CASE XON/XOFF IS DISABLED.
INC DI ;INCRIMENT THE POINTER,
AND DI,BUFMSK ;MODULO BUFSIZ,
CMP DI,IAVAIL[SI] ;STOP IF YOU BUMP INTO YOURSELF,
JNE CTCLUP ;ELSE KEEP LOOKING.
MOV DI,IFIRST[SI] ;IF NO, CONTROL-C, RETURN FIRST CHAR
NONDCTC:
MOV AL,[BX+DI] ;GET THE CHARACTER,
POP BX ;RECOVER BX AGAIN.
MOV ES:MEDIA[BX],AL ;RETURN IT IN THE REQUEST PACKET.
MOV AX,0 ;RETURN NO ERRORS IN AX.
JMP EXIT
SUBTTL INPUT STATUS REQUEST ROUTINE
PAGE
; INPUT STATUS REQUEST
;
RXSTAT:
MOV DI,IFIRST[SI] ;GET POINTER TO FIRST CHAR
CMP DI,IAVAIL[SI] ;IS THE BUFFER EMPTY?
JNE RXFUL
MOV AX,STSBSY ;NO, RETURN STATUS BUISY.
JMP EXIT
RXFUL:
MOV AX,0 ;YES, RETURN STATUS ZERO.
JMP EXIT
SUBTTL INPUT FLUSH REQUEST ROUTINE
; INPUT FLUSH REQUEST
;
INFLUSH:
MOV AX,IAVAIL[SI] ;GET THE POINTER TO THE NEXT EMPTY
MOV IFIRST[SI],AX ;CHAR AND POINT THE FIRST AT IT.
MOV AX,0 ;AND RETURN DONE.
JMP EXIT
SUBTTL WRITE REQUEST ROUTINE
PAGE
; OUTPUT DATA TO DEVICE
;
WRITE:
MOV CX,ES:COUNT[BX] ;GET BYTE COUNT,
MOV DI,ES:XFER[BX] ;GET XFER ADDRESS OFFSET,
MOV AX,ES:XSEG[BX] ;GET XFER SEGMENT.
MOV ES,AX ;STORE IN ES NOW.
TEST LINE[SI],LINSKP ;SHOULD I BE SKIPPING OUTPUT?
JNE WRSUCC
WLUP:
MOV AL,ES:[DI] ;GET THE NEXT CHAR,
INC DI ;AND INC DI PAST IT.
;
; CHECK FOR STRIP PARITY ON OUTPUT.
;
TEST OUTSPEC[SI],OUTSTP ;IS THIS ENABLED?
JE NOOSTP ;NOPE
AND AL,NOT 080H ;YES, WACK OFF BIT SEVEN!
NOOSTP:
;
; CHECK FOR LOWER-TO-UPPER CONVERSION ON OUTPUT
;
TEST OUTSPEC[SI],OUTUPR ;IS THIS ENABLED?
JE NOOUPR ;NOPE
MOV AH,AL ;DO COMPARISON IN AH
AND AH,NOT 080H ;SO YOU CAN STRIP PARITY
CMP AH,'a' ;IS IT GREATER THAN LOWER A?
JL NOOUPR ;NOPE, IT'S NOT LOWER
CMP AH,'z' ;IS IT GREATER THAN LOWER Z?
JG NOOUPR ;NOPE, STILL NOT LOWER
AND AL,NOT 020H ;YES, WHACK OUT THE LOWER BIT.
NOOUPR:
;
; AFTER ALL THE SPECIAL OUTPUT PROCESSING, I DO A HARD WAIT
; FOR A SLOT IN THE OUTPUT BUFFER.
WWAIT:
CALL PUT_OUT ;ATTEMPT TO PUT IN IN OUTPUT BUFFER
CMP AH,0 ;DID IT WORK?
JNE WWAIT ;NO, KEEP TRYING.
LOOP WLUP ;YES, GO GET NEXT CHAR.
CALL START_OUTPUT ;START THE XMITTER IF NECC.
WRSUCC:
MOV AX,0 ;RETURN SUCCESS
JMP EXIT
SUBTTL OUTPUT STATUS REQUEST ROUTINE
; OUTPUT STATUS REQUEST
;
TXSTAT:
MOV AX,OFIRST[SI] ;GET POINTER TO NEXT CHAR OUT
DEC AX ;SUBTRACT ONE FROM IT,
AND AX,BUFMSK ;MODULO 128.
CMP AX,OAVAIL[SI] ;IF THAT EQUALS THE INPUT PNTR,
JNE TXROOM
MOV AX,STSBSY ;THEN THE DEVICE IS BUISY.
JMP EXIT
TXROOM:
MOV AX,0 ;OTHERWIZE THE DEVICE IS OK.
JMP EXIT
SUBTTL I/O CONTROL READ REQUEST
PAGE
;
; IOCONTROL READ REQUEST, RETURN LINE PARAMETERS
;
IOCTLIN:
MOV CX,ES:COUNT[BX] ;GET THE REQUESTED NUMBER OF BYTES
MOV DI,ES:XFER[BX] ;DI IS OFFSET TO USER BUFFER
MOV DX,ES:XSEG[BX] ;SEGMENT IS LAST I NEED FROM PACKET,
MOV ES,DX ;NOW ES:DI POINTS TO USER BUFFER.
CMP CX,10 ;ONLY WORKS WHEN YOU GIVE ME AN
JE DOIOCIN ;10 BYTE BUFFER TO STOMP ON.
MOV AX,ERRBSL ;RETURN AN ERROR IF NOT 10 BYTES.
JMP EXIT
DOIOCIN:
MOV DX,PORT[SI] ;GET PORT NUMBER
ADD DX,LCTRL ;SLIDE UP TO LINE CONTROL
MOV CX,4 ;SET UP FOR PORT LOOP.
GETPORT:
IN AL,DX ;GET NEXT BYTE FROM DEVICE
STOS BYTE PTR [DI] ;STORE THEM IN USER BUFFER
INC DX ;SKIP TO NEXT BYTE
LOOP GETPORT ;READ AND STORE 4 BYTES OF INFO
MOV AX,INSPEC[SI] ;GET THE SPECIAL INPUT BITS
STOS WORD PTR [DI] ;SEND BACK TO USER BUFFER
MOV AX,OUTSPEC[SI] ;GET THE SPECIAL OUTPUT BITS
STOS WORD PTR [DI] ;SEND BACK TO USER BUFFER
MOV AX,BAUD[SI] ;GET BAUD RATE DIVISOR
MOV BX,DI ;SAVE DI FOR A WHILE.
MOV DI,OFFSET ASY_BAUDT+2 ;POINT AT BAUD RATE CONVERSION.
MOV CX,15 ;JUST IN CASE, STOP AT 15 BAUDS
BAUDCIN:
CMP [DI],AX ;IS THIS THE BAUD I AM USING?
JE YESINB ;YES, RETURN THAT
ADD DI,4 ;NO, SKIP TO NEXT ONE
LOOP BAUDCIN ;KEEP LOOKING.
YESINB: ;SEARCH SHOULD ALWAYS TERMINATE ON COMPARE
MOV AX,-2[DI] ;GET THE ASSOCIATED BAUD RATE
MOV DI,BX ;GET DI'S OLD VALUE BACK
STOS WORD PTR [DI] ;STORE THE BAUD RATE BACK.
MOV AX,0 ;RETURN NO ERRORS
JMP EXIT
;
; FLUSH OUTPUT BUFFER REQUEST
;
TXFLUSH:
MOV AX,OAVAIL[SI] ;GET NEXT FREE BYTE OFFSET,
MOV OFIRST[SI],AX ;POINT THE FIRST BYTE OFFSET AT IT.
MOV AX,0
JMP EXIT
SUBTTL I/O CONTROL WRITE REQUEST ROUTINE
PAGE
; IOCONTROL REQUEST: CHANGE LINE PARAMETERS FOR THIS DRIVER
;
IOCTLOUT:
MOV CX,ES:COUNT[BX] ;GET THE REQUESTED NUMBER OF BYTES
MOV DI,ES:XFER[BX] ;DI IS OFFSET TO USER BUFFER
MOV DX,ES:XSEG[BX] ;SEGMENT IS LAST I NEED FROM PACKET,
MOV ES,DX ;NOW ES:DI POINTS TO USER BUFFER.
CMP CX,10 ;ONLY WORKS WHEN YOU GIVE ME A
JE DOIOCOUT ;10 BYTE BUFFER TO READ FROM
MOV AX,ERRBSL ;RETURN AN ERROR IF NOT 10 BYTES.
JMP EXIT
DOIOCOUT:
MOV DX,PORT[SI] ;GET PORT NUMBER
ADD DX,LCTRL ;SLIDE UP TO LINE CONTROL
MOV AL,ES:[DI] ;GET LINE CONTROL FROM USER BUF.
INC DI
OR AL,080H ;SET DLAB BIT FOR BAUD RATE
OUT DX,AL ;OUTPUT TO DEVICE
INC DX ;SKIP TO NEXT BYTE
MOV AL,ES:[DI] ;GET MODEM CONTROL FROM USER BUF.
INC DI
OR AL,08H ;MAKE SURE INTERUPTS ARE ENABLED.
OUT DX,AL ;SEND IT TO DEVICE.
ADD DI,2 ;SKIP OVER THE STATUS BYTES
MOV AX,ES:[DI] ;GET THE SPECIAL INPUT BITS
ADD DI,2
MOV INSPEC[SI],AX ;STORE THE NEW BITS IN UNIT
MOV AX,ES:[DI] ;GET THE OUTPUT SPECIAL BITS
ADD DI,2
MOV OUTSPEC[SI],AX ;STORE THEM ALSO.
MOV AX,ES:[DI] ;GET THE REQUESTED BAUD RATE
MOV BX,DI ;SAVE DI FOR A WHILE.
MOV DI,OFFSET ASY_BAUDT ;POINT AT BAUD RATE CONVERSION
MOV CX,15 ;JUST IN CASE, STOP AT 15 BAUDS
BAUDCOUT:
CMP [DI],AX ;IS THIS THE BAUD I AM USING?
JE YESOUTB ;YES, RETURN THAT
ADD DI,4 ;NO, SKIP TO NEXT ONE
LOOP BAUDCOUT ;KEEP LOOKING.
IN AL,DX ;GET LINE CONTROL REGESTER AGAIN,
AND AL,NOT 080H ;CLEAR DLAB BIT.
DEC DX
OUT DX,AL ;AND WRITE IT BACK OUT.
MOV AX,ERRUM ;RETURN AN ERROR NUMBER IF
JMP EXIT ;BAUD RATE IS NOT IN TABLE.
YESOUTB:
MOV AX,2[DI] ;GET THE ASSOCIATED BAUD RATE
MOV BAUD[SI],AX ;STORE IT IN UNIT TABLE
MOV DX,PORT[SI] ;GET PORT ADDRESS AGAIN,
OUT DX,AL ;WRITE THE LOW BYTE,
INC DX ;SKIP TO NEXT ONE,
MOV AL,AH ;GET HIGH BYTE INTO AL
OUT DX,AL ;OUTPUT IT AS WELL.
ADD DX,LCTRL-BAUD1 ;POINT AT THE LINE CONTROL REG.
IN AL,DX ;READ IT IN,
AND AL,NOT 080H ;CLEAR THE DLAB BIT.
OUT DX,AL ;OUTPUT IT BACK.
MOV AX,0 ;RETURN NO ERROR
JMP EXIT
SUBTTL RING BUFFER ROUTINES
PAGE
; LOCAL ROUTINES FOR MANAGING THE RING BUFFERS ON INPUT
; AND OUTPUT. THE FOLLOWING FOUR ROUTINES ARE ALL CALLED WITH THE
; SAME CONTEXT:
;
; DS:SI POINTS TO THE UNIT STRUCTURE FOR THIS UNIT
; AL IS THE CHARACTER TO BE PLACED IN OR REMOVED FROM A BUFFER
; AH IS THE RETURN STATUS FLAG: 0=SUCESS, -1=FAILURE
;
; ALL OTHER REGESTERS ARE PRESERVED.
;
PUT_OUT PROC NEAR ;PUTS AL INTO THE OUTPUT RING BUFFER
PUSH CX
PUSH DI
PUSHF
CLI ;DISABLE INTERUPTS WHILE I HAVE OAVAIL
MOV CX,OAVAIL[SI] ;GET POINTER TO NEXT AVAILABLE BYTE IN
MOV DI,CX ;OUTPUT BUFFER.
INC CX ;INCRIMENT A COPY OF IT TO SEE IF THE
AND CX,BUFMSK ;BUFFER IS FULL.
CMP CX,OFIRST[SI] ;IS IT?
JE POERR ;YES, RETURN AN ERROR
ADD DI,OBUF[SI] ;NO, CALCULATE ACTUAL OFFSET OF CHAR
MOV [DI],AL ;AND STUFF THE CHARACTER INTO BUFFER
MOV OAVAIL[SI],CX ;UPDATE THE POINTER
MOV AH,0 ;INDICATE SUCCESS
JMP PORET ;AND RETURN
POERR:
MOV AH,-1 ;INDICATE FAILURE.
PORET:
POPF ;RE-ENABLE INTERUPTS
POP DI
POP CX
RET
PUT_OUT ENDP
GET_OUT PROC NEAR ;GETS THE NEXT CHARACTER FROM OUTPUT RING BUFFER
;SURE YOU DISABLE INTERUPTS FIRST.
PUSH CX
PUSH DI
PUSHF ;JUST IN CASE, DISABLE INTERUPTS
CLI ;WHILE IN THIS ROUTINE.
MOV DI,OFIRST[SI] ;GET POINTER TO FIRST CHARACTER TO OUTPUT
CMP DI,OAVAIL[SI] ;IS THE BUFFER EMPTY?
JNE NGOERR ;NO.
MOV AH,-1 ;YES, INDICATE FAILURE
JMP GORET ;AND RETURN
NGOERR:
MOV CX,DI ;SAVE A COPY OF THE POINTER
ADD DI,OBUF[SI] ;CALCULATE ACTUAL ADDRESS
MOV AL,[DI] ;GET THE CHAR INTO AL
MOV AH,0 ;INDICATE SUCCESS.
INC CX ;INCRIMENT THE OFFSET
AND CX,BUFMSK ;MODULO 128
MOV OFIRST[SI],CX ;STORE BACK IN UNIT TABLE.
GORET:
POPF
POP DI
POP CX
RET
GET_OUT ENDP
PUT_IN PROC NEAR ;PUT THE CHAR FROM AL INTO INPUT RING BUFFER
PUSH CX
PUSH DI
PUSHF ;DISABLE INTS WHILE IN THIS ROUTINE
CLI
MOV DI,IAVAIL[SI] ;GET POINTER TO NEXT AVAILABLE SLOT IN BUFFER
MOV CX,DI ;SAVE A COPY OF IT,
INC CX ;AND INCRIMENT THAT COPY (MODULO
AND CX,BUFMSK ;128) TO SEE IF THE BUFFER IS FULL.
CMP CX,IFIRST[SI] ;WELL, IS IT?
JNE NPIERR ;NO, THERE`S ROOM.
MOV AH,-1 ;YES, INDICATE FAILURE
JMP PIRET ;AND RETURN
NPIERR:
ADD DI,IBUF[SI] ;CALCULATE ACTUAL ADDRES,
MOV [DI],AL ;STORE THE CHARACTER THERE
MOV IAVAIL[SI],CX ;UPDATE THE POINTER.
MOV AH,0 ;AND INDICATE SUCCESS.
PIRET:
POPF
POP DI
POP CX
RET
PUT_IN ENDP
GET_IN PROC NEAR ;GETS ONE CARACTER FROM INPUT RING BUFFER INTO AL
PUSH CX
PUSH DI
PUSHF
CLI ;DISABLE INTERUPTS WHILE I LOOK AT IFIRST.
MOV DI,IFIRST[SI] ;GET POINTER TO FIRST CHAR TO READ
CMP DI,IAVAIL[SI] ;IS THE BUFFER EMPTY?
JE GIERR ;THEN YOU CAN`T VERY WELL SQUEEZE WATER OUT OF IT
MOV CX,DI ;MAKE A COPY OF POINTER,
ADD DI,IBUF[SI] ;CALCULATE ACTUAL ADDRESS OF CHAR
MOV AL,[DI] ;GET THE CHAR INTO AL
MOV AH,0 ;INDICATE SUCCESS
INC CX ;INCRIMENT THAT COPY OF YOUR POINTER,
AND CX,BUFMSK ;MODULO THE BUFFER SIZE,
MOV IFIRST[SI],CX ;SO YOU CAN UPDATE THE POINTER.
JMP GIRET
GIERR:
MOV AH,-1 ;RETURN FAILURE INDICATOR
GIRET:
POPF ;RE-ENABLE INTERUPTS BEFORE YOU RETURN
POP DI
POP CX
RET
GET_IN ENDP
SUBTTL INTERUPT SERVICE ROUTINES
PAGE
; THE FOLLOWING ROUTINES ARE WHAT I REALLY CALL AN INTERUPT
; ROUTINE! THESE ROUTINES ARE ONLY CALLED WHEN AN INTERUPT IS GENERATED
; BY THE 8088, NOT BY A SOFWARE CALL THROUGH A LINKED LIST! ONE EASY
; WAY TO TELL A REAL INTERUPT ROUTINE WHEN YOU SEE IT IS TO LOOK AT THE
; LAST INSTRUCTION, WHICH IS AN "INTERUPT RETURN", NOT A FAR RETURN
; LIKE THE SO-CALLED MSDOS "INTERUPT ROUTINE" DOES.
; THESE INTERUPT ROUTINES ARE ENVOKED WHENEVER A CHAR ARRIVES IN THE
; UART, THE UART FINISHES SENDING A CHARACTER OUT, AN ERROR OCCURS
; WHILE READING A CHARACTER INTO THE UART, OR THE MODEM STATUS LINES
; CHANGE.
ASY1ISR:
CLI
PUSH SI
LEA SI,ASY_TAB1 ;POINT AT THE CORRECT TABLE FOR THIS UART,
JMP INT_SERVE ;JUMP INTO THE COMMON INTERUPT SERVER CODE.
ASY2ISR:
CLI
PUSH SI
LEA SI,ASY_TAB2 ;GET UNIT TABLE
;
; IF YOU ADD MORE UNITS, YOU CAN ADD THEM HERE,
; BUT DON'T FORGET TO ADD A JUMP INT_SERVE AFTER
; ASY2ISR'S LEA INSTRUCTION!
;
; THE FOLLOWING CODE IS THE COMMON SHARED CODE THAT ALL THE
; ASYNC PORTS SHARE. IT "KNOWS" WHICH ONE TO TALK TO BY REFERENCING
; THE STRUCTURE POINTED TO BY CS:SI.
INT_SERVE:
PUSH AX ;PUSH ALL THE GP REGESTERS
PUSH BX
PUSH CX
PUSH DX
PUSH DI
PUSH DS ;SAVE THE DATA SEGMENT
PUSH CS ;SO YOU CAN LOAD CS
POP DS ;INTO DS AND FIND YOUR OWN STRUCTURES.
INT_EXIT:
MOV DX,PORT[SI] ;GET THE PORT ADDRESS OF THIS DEVICE
ADD DX,INTID ;SLIDE UP TO THE INTERUPT ID REGISTER
IN AL,DX ;GET THE INTERUPT REASON
TEST AL,1 ;MAKE SURE IT IS VALID
JNE INT_DONE ;IT IS NOT.
MOV AH,0 ;CONVERT IT TO A 16 BIT NUMBER
ADD AX,OFFSET INT_REASON ;ADD IT TO THE JUMP TABLE ADDRESS
MOV DI,AX ;PUT IT IN AN INDEX REGESTER,
JMP [DI] ;AND GO PROCESS THAT TYPE OF INTERUPT
INT_DONE:
ADD DX,LSTAT-INTID ;BECAUSE IT SEEMS TO BE NECESSARY,
IN Al,DX ;READ THE STATUS PORT BEFORE YOU EXIT.
MOV AL,020H ;OUTPUT A 20H TO THE UNDOCUMENTED INTERUPT
OUT 020H,AL ;COMMAND PORT TO ENABLE FURTHER INTERUPTS?
POP DS ;RECOVER ALL THE REGESTERS
POP DI
POP DX
POP CX
POP BX
POP AX
POP SI
IRET
;
; JUMP TABLE OF INTERUPT REASONS. INTERUPT ID REGISTER
; IS USED AS INDEX TO THIS TABLE.
INT_REASON:
DW INT_MODEM ;INT WAS CAUSED BY A MODEM LINE TRANSITION
DW INT_TXMIT ;INT WAS CAUSED BY A TX REGISTER EMPTY
DW INT_RECEIVE ;NEW CHARACTER AVAILABLE IN UART
DW INT_RXSTAT ;CHANGE IN RECEIVER STATUS REGESTER
SUBTTL RECEIVER INTERUPT SERVICE ROUTINE
PAGE
;
; THE INTERUPT SERVICE ROUTINES BELOW ALL HAVE THE
; FOLLOWING CONTEXT:
; -CS AND DS POINT TO THE DRIVER SEGMENT.
; -DS:[SI] POINTS TO THE UNIT STRUCTURE FOR THE ASYNC LINE THAT
; FIRED THE INTERUPT.
; -AX BX CX DX AND DI ARE AVAILABLE FOR SCRATCH. ALL OTHERS
; MUST BE LEFT ALONE OR SAVED AND RECOVERED.
; TO EXIT FROM AN INTERUPT SERVICE ROUTINE, THESE SERVERS MUST
; JUMP TO INT_EXIT.
;
SUBTTL RECEIVER INTERUPT SERVICE ROUTINE
INT_RECEIVE: ;THE UART HAS RECEIVED A NEW CHARACTER, I MUST COPY IT
;INTO THE INPUT TYPEAHEAD BUFFER.
MOV DX,PORT[SI] ;POINT DX BACK AT THE RXBUF REGESTER
IN AL,DX ;GET THE CHARACTER
;
; BEFORE I STORE THE CHARACTER BACK IN THE RING
; BUFFER, I CHECK TO SEE IF ANY OF THE SPECIAL
; INPUT SEQUENCES ARE ENABLED, AND IF THEY
; HAVE BEEN FOUND IN THE INPUT.
;
;
; CHECK FOR XON/XOFF
;
TEST OUTSPEC[SI],OUTXON ;IS XON/XOFF ENABLED?
JE NOXON ;NO, SKIP THIS WHOLE SECTION
CMP AL,'S' AND 01FH ;IS THIS A CONTROL-S?
JNE ISQ ;NO, CHECK FOR CONTROL-Q
OR LINE[SI],LINXOF ;DISABLE OUTPUT.
JMP INT_EXIT ;DON'T STORE THIS CHAR.
ISQ:
CMP AL,'Q' AND 01FH ;IS THIS A CONTROL-Q?
JNE NOXON ;NO, SKIP TO THE NEXT TEST.
TEST LINE[SI],LINXOF ;AM I WAITING FOR THIS ^Q?
JE INT_EXIT ;NO, DON'T STIR UP DRIVER.
AND LINE[SI],NOT LINXOF ;CLEAR THE XOFF BIT,
CALL START_OUTPUT
JMP INT_EXIT ;DON'T BUFFER ^Q'S
NOXON:
;
; CHECK FOR THE SKIP OUTPUT ESCAPE SEQUENCE
;
TEST INSPEC[SI],INCTO ;IS THIS ENABLED?
JE NOCTO ;NOPE.
MOV DI,SKIPP[SI] ;GET OFFSET TO NEXT CHAR
MOV SKIPP[SI],0 ;RESET RECOG. OF THIS SEQ.
CMP SKIPO[DI],AL ;THIS IT?
JNE NOCTO ;NOPE, GO CHECK FOR OTHERS.
INC DI ;YES, INCRIMENT TO NEXT CHAR.
CMP SKIPO[DI],0 ;WAS THAT THE LAST ONE?
JNE NEXTO ;NO, PASS THIS CHAR ON.
XOR LINE[SI],LINSKP ;YES, TOGGLE THE SKIP BIT.
CALL START_OUTPUT ;RATTLE THE XMITTERS CAGE.
INT_EXIT3:
JMP INT_EXIT ;AND EXIT.
NEXTO:
MOV SKIPP[SI],DI ;SET OFFSET TO NEXT CHAR.
NOCTO:
;
; CHECK FOR THE FLUSH INPUT BUFFER SEQUENCE.
;
TEST INSPEC[SI],INCTX ;IS THIS ENABLED?
JE NOCTX ;NOPE.
MOV DI,FLSHP[SI] ;GET OFFSET TO NEXT CHAR
MOV FLSHP[SI],0 ;RESET RECOG. OF THIS SEQ.
CMP FLUSH[DI],AL ;THIS IT?
JNE NOCTX ;NOPE, GO CHECK FOR OTHERS.
INC DI ;YES, INCRIMENT TO NEXT CHAR.
CMP FLUSH[DI],0 ;WAS THAT THE LAST ONE?
JNE NEXTX ;NO, PASS THIS CHAR ON.
MOV AX,IFIRST[SI] ;YES! FLUSH THE BUFFER BY
MOV IAVAIL[SI],AX ;POINTING INPUT TO OUTPUT.
JMP INT_EXIT ;AND EXIT.
NEXTX:
MOV FLSHP[SI],DI ;SET OFFSET TO NEXT CHAR.
NOCTX:
;
; CHECK FOR THE RE-BOOT SYSTEM ESCAPE SEQUENCE.
;
TEST INSPEC[SI],INRES ;IS THIS ENABLED NOW?
JE NOREB ;NO.
MOV DI,REBTP[SI] ;GET OFFSET TO NEXT CHAR
MOV REBTP[SI],0 ;RESET RECOG. OF THIS SEQ.
CMP REBOOT[DI],AL ;THIS IT?
JNE NOREB ;NOPE, GO CHECK FOR OTHERS.
INC DI ;YES, INCRIMENT TO NECT CHAR.
CMP REBOOT[DI],0 ;WAS THAT THE LAST ONE?
JNE NEXTB ;NO, PASS THIS CHAR ON.
MOV AX,0 ;YES, SET UP TO DO A KEYBOARD
MOV DS,AX ;RESET.
ASSUME DS:VECS
MOV AX,1232H ;GET THE QUICK BOOT FLAG,
MOV FLAG,AX ;WARN RESET THIS IS QUICK BOOT
JMP RE_BOOT ;JUMP TO THE RE-BOOT VECTOR.
NEXTB:
MOV REBTP[SI],DI ;SET OFFSET TO NEXT CHAR.
NOREB:
;
; CHECK FOR THE RE-DRAW LAST LINE SEQUENCE.
;
TEST INSPEC[SI],INCTR ;IS THIS ENABLED?
JE NOCTR ;NOPE.
MOV DI,REDRP[SI] ;YES, GET POINTER TO NEXT
MOV REDRP[SI],0 ;RESET IN CASE THIS ISNT IT.
CMP REDRAW[DI],AL ;IS THIS THE NEXT CHAR?
JNE NOCTR ;NO.
INC DI ;YES, INCRIMENT TO NEXT
CMP REDRAW[DI],0 ;WAS THAT THE LAST ONE?
JNE NEXTR ;NO, PASS THIS CHAR ON.
MOV DI,OFIRST[SI] ;YES, THEN SEARCH BACKWARDS
MOV BX,OBUF[SI] ;FOR THE LAST CR.
CRLUP:
DEC DI ;STEP BACK ONE CHAR IN TIME
AND DI,BUFMSK ;(MODULO THE BUFFER SIZE)
CMP DI,OAVAIL[SI] ;BUT STOP IF YOU BACK INTO
JE NOCTR ;THE OTHER END OF BUFFER
CMP BYTE PTR [BX+DI],0DH ;IS THIS A CR?
JNE CRLUP ;NO, KEEP LOOKING.
MOV OFIRST[SI],DI ;YES, SET BUFFER BACK.
CALL START_OUTPUT ;AND MAKE SURE XMITTER SEES IT.
INT_EXIT2:
JMP INT_EXIT
NEXTR:
MOV REDRP[SI],DI ;UPDATE PTR TO PARTIAL SEQ.
NOCTR:
;
; CHECK FOR THE ERASE TO BEGENING OF LINE ESCAPE SEQ.
;
TEST INSPEC[SI],INCTU ;IS THIS ENABLED?
JE NOCTU ;NOPE.
MOV DI,BACKP[SI] ;YES, GET POINTER TO NEXT
MOV BACKP[SI],0 ;RESET IN CASE THIS ISNT IT.
CMP BACKL[DI],AL ;IS THIS THE NEXT CHAR?
JNE NOCTU ;NO.
INC DI ;YES, INCRIMENT TO NEXT
CMP BACKL[DI],0 ;WAS THAT THE LAST ONE?
JNE NEXTU ;NO, PASS THIS CHAR ON.
MOV DI,IFIRST[SI] ;YES, THEN SEARCH BACKWARDS
MOV BX,IBUF[SI] ;FOR THE LAST CR.
MOV CX,-1 ;COUNTING THEM IN CX.
BCRLUP:
INC CX
DEC DI ;STEP BACK ONE CHAR IN TIME
AND DI,BUFMSK ;(MODULO THE BUFFER SIZE)
CMP DI,IAVAIL[SI] ;BUT STOP IF YOU BACK INTO
JE NOCTU ;THE OTHER END OF BUFFER
CMP BYTE PTR [BX+DI],0DH ;IS THIS A CR?
JNE BCRLUP ;NO, KEEP LOOKING.
;NOW CX CONTAINS THE NUMBER OF CHARACTERS TO
;DELETE. I DO THIS THE DUMB WAY: BY SENDING
;THAT MANY BACKSPACE CHARACTERS
MOV AL,8 ;PUT A BACKSPACE IN AL
BAKLUP:
CALL PUT_IN ;PUT IT IN THE INPUT BUFFER
LOOP BAKLUP ;PUT IN A BUNCH OF THEM
JMP INT_EXIT ;WON'T MSDOS BE SUPRISED?
NEXTU:
MOV BACKP[SI],DI ;UPDATE PTR TO PARTIAL SEQ.
NOCTU:
;
; NONE OF THE SPECIAL INPUT SEQUENCES PANNED OUT, SO
; I'LL JUST STUFF THE CHARACTER INTO THE INPUT RING
; BUFFER THIS TIME.
STUFF_IN:
CALL PUT_IN ;PUT THE CHARACTER IN THE RING BUFFER
CMP AH,0 ;WAS THERE ROOM?
JE INT_EXIT2 ;YES, JUST RETURN
OR MODEM[SI],MODOVR ;NO, SET THE OVERFLOW BIT
TEST INSPEC[SI],INBEL ;ARE OVERFLOW BELLS ENABLED?
JE INT_EXIT2 ;NO, SKIP IT.
TEST LINE[SI],LINEXP ;IS XMITTER EXPECTING AN INTERUPT?
JNE INT_EXIT2 ;YES, LEAVE HIM ALONE.
MOV AL,7 ;NO, SEND A BELL IMMEDIATELY
MOV DX,PORT[SI] ;GET PORT ADDRESS,
OUT DX,AL ;AND SEND A CHAR TO XMITTER TO START
OR LINE[SI],LINEXP ;SET INTERUPT EXPECTED BIT.
JMP INT_EXIT
SUBTTL RECEIVER LINE STATUS INTERUPT ROUTINE
PAGE
; THE LSTAT REGISTER DETECTED A RECEIVER ERROR CONDITION
INT_RXSTAT:
ADD DX,LSTAT-INTID ;READ THE REGESTER AND FIND OUT WHY
IN AL,DX
TEST INSPEC[SI],INEPC ;DO I RETURN THEM AS CODES?
JE NOCODE ;NO, WHAT ELSE?
AND AL,01EH ;YES, MASK OFF ALL BUT ERROR BITS,
OR AL,080H ;SET THE PARITY BIT TO MAKE IT
;AN ILLEGAL CHARACTER,
JMP STUFF_IN ;AND PUT IT IN THE INPUT BUFFER.
NOCODE:
OR MODEM[SI],MODERR ;SET A STATUS BIT THAT WILL
;NOTIFY MSDOS ON THE NEXT REQUEST
JMP INT_EXIT
PAGE
SUBTTL MODEM STATUS INTERUPT SERVICE ROUTINE
; THE MODEM STATUS REGESTER DETECTED A CHANGE IN ONE OF THE
; MODEM LINES. I COULD CHECK THE "DELTA BITS" TO SEE EXACTLY WHICH
; LINE TRIGGERED THIS INTERUPT, BUT I JUST CHECK ALL OF THEM WHEN
; I GET ANY MODEM STATUS INTERUPT.
INT_MODEM:
ADD DX,MSTAT-INTID ;READ THE MODEM STATUS REGESTER
IN AL,DX
;*********************************
;CHECK THE CARIER-DETECT BIT (CD)
TEST AL,080H ;IS CARRIER DETECT OFF?
JNE MSDSR ;NO, CHECK DSR NEXT
TEST OUTSPEC[SI],OUTCDF ;IS CD THE OFF-LINE SIGNAL?
JE MSDSR ;NO, IGNORE CD THEN.
OR MODEM[SI],MODOFF ;YES,SET OFLINE FOR NEXT READ REQUEST
;**************************************
;CHECK THE DATA-SET-READY BIT (DSR)
MSDSR:
TEST AL,020H ;IS DSR OFF?
JNE DSRON ;NO, GO CHECK TO SEE IF I WAS WAITING ON IT.
TEST OUTSPEC[SI],OUTDSR ;IS DSR THE OUTPUT DATA THROTTLE FLG?
JE DSROFF ;NO, MABY IT'S OFFLINE SIGNAL
OR LINE[SI],LINDSR ;YES, SUSPEND OUTPUT WAITING ON DSR
DSROFF:
TEST OUTSPEC[SI],OUTDRF ;IS DSR THE OFFLINE SIGNAL?
JE MSCTS ;NOPE.
OR MODEM[SI],MODOFF ;YES, SET FLAG FOR NEXT READ.
JMP MSCTS
DSRON:
TEST LINE[SI],LINDSR ;WAS I WAITING FOR DSR TO COME ON?
JE MSCTS ;NO, IGNORE IT.
AND LINE[SI],NOT LINDSR ;YES, CLEAR THE BIT, AND
CALL START_OUTPUT ;START OUTPUT BACK UP AGAIN.
;****************************************
;CHECK THE CLEAR-TO-SEND BIT (CTS)
MSCTS:
TEST AL,010H ;IS CTS OFF?
JNE CTSON ;NO, GO CHECK TO SEE IF ITS EXPECTED
TEST OUTSPEC[SI],OUTCTS ;IS CSR THE OUTPUT DATA THROTTLER?
JE CTSOFF ;NO, MABY IT'S OFFLINE SIGNAL
OR LINE[SI],LINCTS ;YES, SUSPEND OUTPUT.
CTSOFF:
TEST OUTSPEC[SI],OUTCTS ;IS CTS THE OFF-LINE SIGNAL?
JE INT_EXIT4 ;NOPE.
OR MODEM[SI],MODOFF ;YES, SET FLAG FOR NEXT READ.
JMP INT_EXIT
CTSON:
TEST LINE[SI],LINCTS ;WAS I WAITING FOR THIS CTS?
JE INT_EXIT4 ;NO, THERE'S NOTHING LEFT TO CHECK.
AND LINE[SI],NOT LINCTS ;YES, CLEAR THE BIT, AND
CALL START_OUTPUT ;START OUTPUT UP AGAIN.
INT_EXIT4:
JMP INT_EXIT
SUBTTL TRANSMITTER INTERUPT SERVICE ROUTINE
PAGE
; THE TRANSMITTER HOLDING REGESTER IS EMPTY, LOOK TO SEE IF
INT_TXMIT: ;THERE ARE MORE CHARS TO PRINT NOW.
AND LINE[SI],NOT LINEXP ;CLEAR INTERUPT EXPECTED BIT.
CALL START_OUTPUT ;START THE NEXT CHARACTER
JMP INT_EXIT
;ROUTINE TO START THE NEXT CHARACTER PRINTING ON THE UART, IF OUTPUT
;IS NOT BEING SUSPENDED FOR ONE REASON OR ANOTHER.
;THIS ROUTINE MAY BE CALLED FROM REQUEST ROUTINES, OR FROM INTERUPT
;SEVICE ROUTINES.
; THIS ROUTINE DESTROYS AX AND DX.
; SX MUST POINT AT THE UNIT STRUCTURE.
START_OUTPUT PROC NEAR
PUSHF ;SAVE THE FLAGS SO I CAN
CLI ;DISABLE INTERUPTS
TEST LINE[SI],LINIDL ;AM I IN HOLD OUTPUT MODE?
JNE DONT_START ;YES, DON'T SEND ANY MORE CHARS.
CALL GET_OUT ;CHECK TO SEE IF THERE IS A CHAR IN THE BUF
CMP AH,0 ;WELL, WAS THERE?
JNE DONT_START ;NO, BUFFER IS EMPTY
MOV DX,PORT[SI] ;YES, POINT DX AT THE TX OUT REGISTER
OUT DX,AL ;SEND HIM THE CHARACTER
OR LINE[SI],LINEXP ;WARN EVERYBODY THAT I'M BUSY.
DONT_START:
POPF
RET
START_OUTPUT ENDP
; THE FOLLOWING LABEL DEFINES THE END OF THE DRIVER, SO I
; CAN TELL DOS HOW BIG I AM.
ASYNC_END:
SUBTTL INITIALIZATION REQUEST ROUTINE
PAGE
;
; THE INITIALIZE DRIVER ROUTINE IS STORED AFTER THE "END"
; OF THE DRIVER HERE SO THAT THIS CODE CAN BE THROWN AWAY AFTER
; THE DEVICE HAS BEEN INITIALIZED. THIS CODE IS ONLY CALLED TWICE:
; ONCE TO INITIALIZE EACH OF THE ASYNC UNITS THAT THIS DRIVER
; CONTAINS. (HOPEFULLY, MSDOS DOESN'T WRITE ANYTHING ON TOP OF
; THIS CODE UNIT BOTH UNITS ARE INITIALIZED.
; THE CONTEXT OF THE INITIALIZE CODE BELOW IS THE SAME AS
; ALL THE OTHER REQUEST ROUTINES EARLIER IN THE DRIVER.
;
; INITIALIZE THE DRIVER AND DEVICE
;
ASYNC_INIT:
MOV AX,OFFSET ASYNC_END ;GET THE SIZE OF THE DRIVER
MOV ES:XFER[BX],AX ;SEND THAT BACK IN PACKET
MOV ES:XSEG[BX],CS ;SEND THE CODE SEGMENT ALSO.
;I HAVE SATISFIED ALL THE REQIREMENTS OF THE
;INIT FUNCTION TO RETURN IN THE I/O PACKET, SO
;I CAN DESTROY THE CONTENTS OF ES:BX AND USE
;THEM FOR OTHER THINGS.
MOV AX,0 ;POINT ES AT THE VECTOR SEGMENT
MOV ES,AX ;SO CAN INITIALIZE THE VECTORS
MOV AX,ISRADR[SI] ;GET ADRS OF INTERUPT SERVICE ROUTINE
;THE FOLLOWING CODE IS SPECIFIC TO THE IBM:
;BASIC USES LOCATIONS 400 AND 402 TO FIND
;THE PORT ADDRESSES OF COM1 AND COM2. IF I
;ZERO THESE, THEN BASIC CANNOT MUCK UP THE
;REGESTERS ON ME ANY MORE! (IT STILL
;DISABLES INTERUPTS, THOUGH. BUMMER!)
MOV DI,400 ;POINT AT THE ASYNC ADDRESS LIST
CLD
STOS WORD PTR [DI] ;CLOBBER THE FIRST ONE,
STOS WORD PTR [DI] ;AND THE SECOND ONE.
;NOW WE'RE BACK ON THE GENERIC MSDOS TRACK.
MOV DI,VECT[SI] ;GET ADRS OF VECOTR,
STOS WORD PTR [DI] ;STORE THE OFFSET THERE, THEN
MOV ES:[DI],CS ;THE SEGMENT IN THE FOLLOWING WORD.
MOV CX,DI ;GET THE VECTOR NUMBER,
SUB CL,022H ;SUBTRACT BIAS TO HARDWARE INTS,
SAR CL,1 ;DIVIDE BY 4 TO CONVERT TO
SAR CL,1 ;HARDWARE INTERUPT NUMBER.
MOV AH,1 ;SHIFT A MASK BY THAT MUCH TO
SAL AH,CL ;CREATE INTERUPT ENABLE MASK BIT,
NOT AH ;WHICH IS ACTIVE LOW...
IN AL,021H ;GET SYSTEM HARDWARE INTERUPT MASK
AND AL,AH ;AND MY BIT OUT OF IT,
OUT 021H,AL ;WRITE IT BACK OUT AGAIN.
MOV DX,PORT[SI] ;GET THE PORT ADDRESS OF THIS LINE
ADD DX,INTID
INT_CAN:
IN AL,DX ;GET INTERUPT ID REGESTER
TEST AL,1 ;IF HE HAS ANYTHING TO COMPLAINE
JNZ INT_NONE ;ABOUT, READ THEM ALL AND IGNORE.
ADD DX,LSTAT-INTID ;JUST TO MAKE UART HAPPY, READ THE
IN AL,DX ;LINE STATUS AND
ADD DX,MSTAT-LSTAT ;THE MODEM STATUS TO
IN AL,DX ;"RESET INTERUPT CONTROL"
ADD DX,RXBUF-MSTAT ;READING THE RECEIVER MIGHT
IN AL,DX ;HELP ALSO.
ADD DX,INTID-RXBUF ;POINT BACK AT INTERUPT ID,
JMP INT_CAN ;AND DO THIS AGAIN.
INT_NONE:
ADD DX,LSTAT-INTID ;CALC ADDRESS OF LINE STATUS,
IN AL,DX ;INPUT IT OR SOMETIMES IT DOESN'T WORK
ADD DX,LCTRL-LSTAT ;CALC ADDRESS OF LINE CONTROL REG
MOV AL,LINE[SI] ;GET THE DEFAULT LINE
OR AL,DLAB ;SET THE DIVISOR LATCH BIT
OUT DX,AL ;SET UP DEFAULT LINE CHARS
SUB DX,LCTRL ;POINT BACK AT FIRST PORT
MOV AX,BAUD[SI] ;GET DIVISOR VALUE FOR BAUD RATE
OUT DX,AL ;SEND LOW BYTE
INC DX ;INC TO HIGH BYTE PORT
MOV AL,AH ;GET HIGH BYTE,
OUT DX,AL ;AND SEND TO BOARD.
ADD DX,LCTRL-1 ;POINT AT LINE CONTROL AGAIN,
MOV AL,LINE[SI] ;GET DEFAULT LINE CONTROL BITS AGAIN
OUT DX,AL ;SET THEM WITHOUT DLAB ON.
MOV LINE[SI],0 ;RE-USE LINE OFFSET AS STATUS
SUB DX,LCTRL-INTEN ;POINT DX AT INTERUPT ENABLE PORT
MOV AL,ALLINT ;SET UP TO GET ALL POSSIBLE INTS
OUT DX,AL ;IN THE INTEN REGESTER.
ADD DX,MCTRL-INTEN ;POINT AT MODEM STATUS REGESTER
MOV AL,MODEM[SI] ;GET THE DEFAULT MODEM STATUS BITS,
OUT DX,AL ;AND SET THEM IN MCTRL.
MOV MODEM[SI],0 ;RE-USE THIS BYTE FOR INPUT STATUS.
TEST INSPEC[SI],INXON ;IS INPUT THROTTLED WITH XON?
JE DONE_INIT ;NO, LEAVE HIM BE.
MOV AL,'Q' AND 01FH ;YES, SEND A CONTROL-Q
MOV DX,PORT[SI] ;TO THE DEVICE AT INIT TIME,
OUT DX,AL ;TO MAKE SURE IT WAKES UP.
DONE_INIT:
MOV AX,0 ;RETURN NO ERRORS.
JMP EXIT
DRIVER ENDS
END
