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Assembly Source File | 1987-05-11 | 36.8 KB | 1,065 lines

page 58,132 ; file: MIDI.ASM TITLE Z8470 MIDI driver for MSDOS SUBTTL DESCRIPTION ;THINGS TO ADD: (DELETE THESE LINES AS YOU IMPLIMENT THEM) ;data errors reported at the time you get to that byte in read buffer ; ; ; Loadable midi device driver for msdos. ; Written by: Mike Higgins ; Copyright (c) April 1984 by The Computer Entomologist. ; ;************************************************************************ ; This file implements an interrupt driven character device driver ;for the midi board described in the article: "A MIDI Project", by Jay ;Kupicky, BYTE Magazine, June 1986, V.11 N.6. The driver will work on any ;similar board that uses the Z8470 Z80 DART chip. This code should work ;with several DART chips on one board, if you change the appropriate ;counters, add structures and buffers for each UART, and check the interrupt ;and initialization code. ; Why write or use such a driver? Because the code written by ;Jay Kubicky could only be compiled on one specific C compiler, and ;required non-standard communication channels between the main code and ;the assembly driver. ; This driver implements the MIDI board as a standard MSDOS character ;device that can be called from any program written in any language. Even ;interpretative BASIC can open this device and perform any function that ;the board is capable of. All the communication with the driver is ;done with standard reads,writes, and IOCTL calls. The character input/ ;output is the MIDI data, and the IOCTL data allows a program to find the ;state of the MIDI UARTS, and to perform initialization functions. (Test ;for data available or error status, flush buffers, change echo/thru ;modes). Additionally, there is a read-with-timeout feature that ;allows the driver to return to you if no data arrives after a specified ;number of milliseconds. ; This driver implements a 128 byte buffer on input and output to ;make catching all the MIDI data as easy as possible for you programs. ;The output buffer allows your programs to send multiple byte commands ;without having to wait on each byte: your processing can continue while ;the driver sends the bytes out one at a time for you. ; There is also a "MIDI out/through" option in this driver that ;will copy, if enabled, any incoming bytes immediately to the associated ;MIDI out port. I call this a "poor man's MIDI merge" because it will ;scramble MIDI commands together if they arrive at the output buffer ;too close together. But it does have some limited applications. Note ;that a very intelligent MIDI merge program would be easy to write as an ;application on top of this board and driver. (Requires both UARTs hooked ;up with MIDI drivers and receivers, like mine is). ; While initializing the uarts, this driver also initializes the on ;board clock chip. You can get direct access to this clock for timing midi ;events, and the driver uses this clock to count time for the read-with- ;timeout feature. The delta times are in "digital" milliseconds, so the ;value changes 1024 times each second. The two byte clock value from timer2 ;will allow you to time anything that is 64 seconds or less, which should be ;long enough for any typical MIDI use. (You will have to store delta times, ;not absolute time). On my version of the board, timer2 overflows into ;timer3, so this can be considered a 16bit extension of the regular timer. ;This results in a four byte clock that only overflows after 136 ;years. If you can keep your PC running continuously that long (without ;re-booting) I'll be very impressed! ; ;************************************************************************ ; ; Permission is hereby 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 responsibility for ;any damage this software may do to his system. ; ; Nasty notices aside, if you have any questions about this software, ;you can reach me at the address below. If you implement 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 ; ; ; ASSEMBLY INSTRUCTIONS: ; MASM MIDI,MIDI,MIDI,NUL ; LINK MIDI,MIDI,MIDI,NUL ; EXE2BIN MIDI ; COPY MIDI.BIN A: (IF NOT THERE ALREADY) ; ADD THE FOLLOWING LINE TO A:CONFIG.SYS: ; DRIVER=MIDI.BIN ; RE-BOOT YOUR SYSTEM AND IT'S THERE! ; ; NOTE: ; ; There are hooks in the driver for features that do not work ; yet. 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 implement 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 PORT OFFSETS AND IMPORTANT BOARD CONSTANTS MIDDAT EQU 0 ;DATA REGESTER MIDCON EQU 2 ;CONTROL REGESTER MIDB EQU 1 ;BITS TO FORCE IO ADDRESS TO UART B WITH OR MIDA EQU NOT MIDB ;MASK TO FORCE IO ADDR TO UART A WITH AND ; ; BIT ASSIGNMENTS FOR THE STATUS WORD IN EACH UNIT STRUCTURE OUTINT EQU 1 ;CHARACTER SENT OUT, INTERUPT SHOULD BE COMMING OUTHRU EQU 2 ;INPUT IS ECHOED THRU OUTPUT (POOR MANS MIDI OUT/THRU ; ; BIT ASSIGNMENTS FOR THE ERVAL WORD IN EACH UNIT STRUCTURE ERITMO EQU 1 ;INPUT TIMEOUT ERROR EROTMO EQU 2 ;OUTPUT TIMEOUT ERROR ERIBFO EQU 4 ;INPUT BUFFER OVERFLOW EROBFO EQU 8 ;OUPUT BUFFER OVERFLOW ERPARE EQU 10H ;PARITY ERROR (NOT ENABLED) ERFRAM EQU 20H ;FRAMING ERROR ERRXOV EQU 40H ;RECEVER OVERRUN (NOT LIKELY) ; ;BIT DEFINITIONS FOR ALL THE BITS/REGESTERS IN THE Z8470 ZILOG Z80 DART CHIP ; ;WRITE REGESTER 0 BITS ZRESET EQU 010H ;RESET EXT/STATUS INTERUPTS ZCHANR EQU 018H ;CHANNEL RESET ZRXINT EQU 020H ;ENABLE INT ON NEXT Rx CHARACTER ZTXINT EQU 028H ;RESET Tx INT PENDING ZERRES EQU 030H ;ERROR RESET ZREINT EQU 038H ;RETURN FROM INT (CHANNEL A ONLY) ;WRITE REGESTER 1 BITS W1EXTI EQU 001H ;EXT INT ENABLE W1TXINT EQU 002H ;Tx INT ENABLE W1STAT EQU 004H ;STATUS EFFECTS VECTOR (CHANNEL B ONLY) W1RXDIS EQU 000H ;Rx INT DISABLE W1RX1ST EQU 008H ;Rx INT ON FIRST CHARACTER W1RXALP EQU 010H ;Rx INT ON ALL CHARACTERS (PARITY AFFECTS VECTOR) W1RXALL EQU 018H ;Rx INT ON ALL CHARACTERS (PARITY DOESN'T AFF. VEC) W1WAITR EQU 020H ;WAIT/READY ON R/T W1WAITF EQU 040H ;WAIT/READY FUNCTION W1WAITE EQU 080H ;WAIT/READY ENABLE ;WRITE REGESTER 3 BITS W3RXEN EQU 001H ;Rx ENABLE W3AUTO EQU 020H ;AUTO ENABLES W3RX5 EQU 000H ;Rx 5 BITS/CHAR W3RX7 EQU 040H ;Rx 7 BITS/CHAR W3RX6 EQU 080H ;Rx 6 BITS/CHAR W3RX8 EQU 0C0H ;Rx 8 BITS/CHAR ;WRITE REGESTER 4 BITS W4PARE EQU 001H ;PARITY ENABLE W4PEVN EQU 002H ;PARITY IS EVEN W4PODD EQU 000H ;PARITY IS ODD W4STOP1 EQU 004H ;ONE STOP BITS W4STP15 EQU 008H ;1.5 STOP BITS W4STOP2 EQU 00CH ;TWO STOP BITS W4X1 EQU 000H ;X1 CLOCK MODE W4X16 EQU 040H ;X16 CLOCK MODE W4X32 EQU 080H ;X32 CLOCK MODE W4X64 EQU 0C0H ;X64 CLOCK MODE ;WRITE REGESTER 5 BITS W5RTS EQU 002H ;SET RTS BIT IN OUTPUT W5TXEN EQU 008H ;Tx ENABLE W5BREAK EQU 010H ;SEND BREAK W5TX5 EQU 000H ;Tx 5 BITS/CHARACTER W5TX7 EQU 020H ;Tx 7 BITS/CHAR W5TX6 EQU 040H ;Tx 6 BITS/CHAR W5TX8 EQU 060H ;Tx 8 BITS/CHAR W5DTR EQU 080H ;SET DTR BIT IN OUTPUT ;READ REGESTER 0 BITS RXCHAR EQU 001H ;CHARACTER HAS BEEN RECEIVED INTPEND EQU 002H ;INTERUPT IS PENDING (CHANNEL A ONLY) TXFREE EQU 004H ;Tx BUFFER IS EMPTY CD EQU 008H ;CARRIER DETECT LINE IS ON RI EQU 010H ;RING INDICATOR LINE IS ON CTS EQU 020H ;CLEAR TO SEND LINE IS ON BREAK EQU 080H ;BREAK HAS BEEN DETECTED ;READ REGESTER 1 BITS R1ALL EQU 001H ;ALL SENT (Tx BUFFER?) R1PERR EQU 010H ;PARRITY ERROR R1RXOVR EQU 020H ;Rx OFERRUN ERROR R1FRAME EQU 040H ;FRAMING ERROR ;READ REGESTER 2 BITS VECMASK EQU 006H ;REASON-FOR-INTERUPT BITS VECB EQU 008H ;UART B FIRED INTERUPT ; ;REGESTER OFFSETS AND BIT ASSIGNMENTS FOR THE CLOCK TIMER CHIP TIMER1 EQU -3 ;OFFSET FROM CONTROL REGESTER TO TIMER DATA 1 TIMER2 EQU -2 ;TIMER 2 DATA REGESTER TIMER3 EQU -1 ;TIMER 3 T1 EQU 0 ;CONTROLLER TIMER 1 SELECT VALUE T2 EQU 040H ;SELECT TIMER 2 T3 EQU 080H ;SELECT TIMER 3 LMSB EQU 030H ;READ TIMER REGESTERS IN LITTLE ENDIAN MODE SHOOT EQU 002H ;ONE SHOT MODE RATE EQU 004H ;RATE GENERATOR MODE SQUARE EQU 006H ;SQUARE WAVE MODE LATCH EQU 0 ;LATCH THE CURRENT VALUES FOR READING ; SUBTTL DRIVER LIST HEAD PAGE ;************************************************************************* ; ; BEGENING OF DRIVER CODE. ; DRIVER SEGMENT ASSUME CS:DRIVER,DS:DRIVER,ES:DRIVER ; ORG 0 ;DRIVERS START AT 0 MIDIB: DW MIDIA,-1 ;POINTER TO NEXT DEVICE: DOS FILLS IN SEG. DW DEVCHR OR DEVIOC ;CHARACTER DEVICE, IOCTL ALLOWED DW STRATEGY ;OFFSET TO STRATEGY ROUTINE. DW REQUESTB ;OFFSET TO "INTERUPT" ENTRYPOINT. DB "MIDIB " ;DEVICE NAME. MIDIA: 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 REQUESTA ;I/O REQUEST ROUTINT DB "MIDIA " debug dd 0b0000000h notify macro char ; local store ; push es ; push di ; push ax ; mov al,'&char' ; les di,CS:debug ; stos byte ptr [di] ; inc di ; cmp di,80*25*2 ; jl store ; xor di,di ;store: ; mov word ptr CS:debug,di ; mov al,'<' ; stos byte ptr es:[di] ; pop ax ; pop di ; pop es endm SUBTTL DRIVER INTERNAL DATA STRUCTURES PAGE ; MIDI_UNITS EQU 2 ;NUMBER OF UNITS THIS DRIVER IS BUILT FOR MIDI_VEC DW 028H ;INTERUPT VECTOR ADDRESS (NOT VECTOR NUMBER) CLOCK_PORT DW 0FFA7H ;PORT OF CLOCK CONTROL REGESTER ; UNIT STRUC ;EACH UNIT HAS A STRUCTURE DEFINING IT'S STATE: PORT DW ? ;I/O PORT ADDRESS STATUS DW ? ;STATUS BITS TIMEOUT DW ? ;TIMEOUT CONSTANT ON READ OR WRITE REQUEST ERVAL DW ? ;BIT ENCODED ERRORS SINCE LAST YOU LOOKED EROFF DW ? ;OFFSET TO FIRST CHARACTER AFTER ERROR 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 MIDI UNIT ; THE STRUCTURES FOR ALL THE UARTS MUST BE ORGANIZED TOGETHER INTO ; A CONTIGUOUS TABLE, BECAUSE THE INTERUPT SERVICE ROUTINE SCANS ; THROUGH THEM WHILE DETERMINING WHICH DART FIRED THE INTERUPT. ; SIMILARLY, THE STRUCTURES FOR THE TWO UARTS IN EACH DART MUST BI ; IN A-B ORDER IN THIS TABLE. ; MIDI_TABA: UNIT <0FFA0H,0,-1,0,-1,0,0,INABUF,0,0,OUTABUF> UNIT_SIZE EQU $-MIDI_TABA MIDI_TABB: UNIT <0FFA1H,0,-1,0,-1,0,0,INBBUF,0,0,OUTBBUF> ;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 INABUF DB BUFSIZ DUP (?) INBBUF DB BUFSIZ DUP (?) OUTABUF DB BUFSIZ DUP (?) OUTBBUF DB BUFSIZ DUP (?) ; ; 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. PUBLIC STRATEGY 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 ; I/O REQUEST ROUTINES PUBLIC REQUESTA REQUESTA: ;MIDIA HAS BEEN REQUESTED PUSH SI ;SAVE SI SO YOU CAN MOV SI,OFFSET MIDI_TABA ;GET THE DEVICE UNIT TABLE ADDRESS. JMP GEN_REQUEST ;THE GENERIC DRIVER DOES THE REST. REQUESTB: ;MIDIB HAS BEEN REQUESTED TO DO SOMETHING PUSH SI ;SAVE SI MOV SI,OFFSET MIDI_TABB ;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 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, MOV DI,AX ;AND ADD TO THE TABLE START ADDRESS MOV AX,STSERR OR ERRUC ;SEND UNKNOWN COMMAND ERROR FOR EXIT JMP MIDI_FUNCS[DI] ;JUMP TO THE APPROPRIATE ROUTINE ; ; TABLE OF OFFSETS TO ALL THE DRIVER FUNCTIONS ; MIDI_FUNCS DW MIDI_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 EXIT ;NON-DESTRUCTIVE READ DW EXIT ;INPUT STATUS DW EXIT ;FLUSH INPUT BUFFER DW WRITE ;WRITE DW WRITE ;WRITE WITH VERIFY DW EXIT ;OUTPUT STATUS DW EXIT ;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: CALL GET_CLOCK ;GET CLOCK CURRENT VALUE FOR READ- MOV DX,AX ;WITH-TIMEOUT TEST, AND STORE IT IN DX MOV CX,ES:COUNT[BX] ;GET THE REQUESTED NUMBER OF BYTES LES DI,DWORD PTR ES:XFER[BX] ;DI IS OFFSET TO USER BUFFER MOV BX,TIMEOUT[SI] ;GET THE TIMEOUT LIMIT. RLUP: MOV AX,EROFF[SI] ;CHECK TO SEE IF IT'S TIME CMP AX,IFIRST[SI] ;TO REPORT AN ERROR JE ERR_READ CALL GET_IN ;GET NEXT CHAR FROM INPUT BUFFER CMP AH,0 ;WAS THERE ONE? JNE READ_WAIT ;NO, TEST FOR TIMEOUT STOS BYTE PTR[DI] ;YES,WRITE THIS BYTE OUT ;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 AX,STSDNE ;RETURN NO ERRORS IN AX IF DONE. JMP EXIT ERR_READ: ;NOW IS THE TIME TO REPORT AN INPUT ERROR MOV AX,-1 ;DISABLE THE ERROR CHECKING BY MOV EROFF[SI],AX ;SETTING OFFSET TO FFFF OR ERVAL[SI],ERIBFO ;SET INPUT BUFFER OVERFLOW BIT JMP ERR_RET READ_WAIT: CMP BX,0FFFFH ;IF THE TIMEOUT VALUE IS MAX INT, JE RLUP ;LOOP BACK UP FOREVER CALL GET_CLOCK SUB AX,DX ;CALCULATE THE DELTA TIME NEG AX CMP AX,BX ;COMPARE AGAINST THE TIMOUT LIMIT JB RLUP ;LOOP BACK IF TIME IS STILL OK OR ERVAL[SI],ERITMO ;TELL THEM A TIMEOUT ERROR HAPPENED ERR_RET: LES BX,PACKHEAD ;GET IO PACKET BACK SUB ES:COUNT[BX],CX ;TELL HIM HOW MANY BYTES MADE IT, AND MOV AX,STSBSY ;RETURN A READ JMP EXIT ;FAULT ERROR. ; SUBTTL WRITE REQUEST ROUTINE PAGE ; OUTPUT DATA TO DEVICE ; WRITE: CALL GET_CLOCK ;GET CLOCK VALUE FOR TIMEOUT TEST MOV DX,AX ;DX WILL CONTAIN STARTING TIME MOV CX,ES:COUNT[BX] ;GET BYTE COUNT, LES DI,DWORD PTR ES:XFER[BX] ;GET XFER ADDRESS MOV BX,TIMEOUT[SI] ;GET TIMEOUT LIMIT WLUP: MOV AL,ES:[DI] ;GET THE NEXT CHAR DOS SENT YOU CALL PUT_OUT ;ATTEMPT TO PUT IN IN OUTPUT BUFFER CMP AH,0 ;DID IT WORK? JNE WWAIT ;NO, GO TEST FOR TIMEOUT INC DI ;SKIP TO NEXT BYTE CALL START_OUTPUT ;START THE XMITTER IF NECC. LOOP WLUP ;YES, GO GET NEXT CHAR. MOV AX,STSDNE ;RETURN SUCCESS JMP EXIT WWAIT: CALL GET_CLOCK ;GET CURRENT CLOCK TIME SUB AX,DX ;CALCULATE NUMBER OF MILISECONDS SINCE START NEG AX CMP AX,BX ;HAVE WE WAITED LONG ENUF? JB WLUP ;NO, KEEP TRYING OR ERVAL[SI],EROTMO ;TELL THEM OUTPUT TIMED OUT LES BX,PACKHEAD ;GET IO PACKET BACK SUB ES:COUNT[BX],CX ;TELL HIM HOW MANY BYTES MADE IT, AND MOV AX,STSBSY ;YES, RETURN A WRITE FAULT ERROR JMP EXIT ; SUBTTL I/O CONTROL READ REQUEST PAGE ; ; IOCONTROL READ REQUEST, RETURN INTERNAL STRUCTURE ; 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,UNIT_SIZE ;ONLY WORKS WHEN YOU GIVE ME A JE DOIOCIN ;RIGHT SIZED BUFFER TO STOMP ON. MOV AX,STSERR OR ERRBSL ;RETURN AN ERROR IF NOT RIGHT. JMP EXIT DOIOCIN: REP MOVSB ;JUST COPY THE STRUCTURE TO CALLER SUB SI,UNIT_SIZE ;POINT BACK AT UNIT STRUCTURE MOV AX,0 ;SO YOU CAN ZERO THE MOV ERVAL[SI],AX ;ERROR WORD EVERY TIME THEY READ IT MOV AX,STSDNE ;RETURN NO ERRORS JMP EXIT ; SUBTTL I/O CONTROL WRITE REQUEST ROUTINE PAGE ; ; I USE THIS COMMAND TO COMMUNICATE VARIOUS SPECIAL COMMANDS ; TO THE DRIVER. EACH BYTE SENT IS A SEPARATE COMMAND TO FLUSH A ; BUFFER, CLEAR STATUS, SET SPECIAL FLAGS, ETC. ; IOCTLOUT: MOV CX,ES:COUNT[BX] ;GET THE BYTE COUNT LES DI,DWORD PTR ES:XFER[BX] ;AND THE ADDRESS IOWRITE: ;LOOP FOR ALL IO CONTROL WRITE BYTES MOV BL,ES:[DI] ;GET NEXT BYTE INC DI ;SKIP TO FOLLOWING ONE AND BX,7 ;CHOP OUT LOWER 3 BITS SHL BX,1 ;CONVERT TO WORD INDEX CMP BL,IOWSIZE ;IS THIS A LEGAL REQUEST? JG IOWERR ;NO RETURN A WRITE ERROR JMP WORD PTR CS:IOTAB[BX] ;YES, EXECUTE APPROPRIATE CODE IOTAB DW IOWFLI ;FLUSH INPUT BUFFER DW IOWFLO ;FLUSH OUTPUT BUFFER DW IOWTIM ;SET IO TIMEOUT LIMIT DW IOWSEO ;SET BYTEWISE MIDI OUTPUT/THRU FLAG DW IOWCLO ;CLEAR POOR MANS OUTPUT/THRU MERGE FLAG IOWSIZE EQU $-IOTAB IOWFLI: ;FLUSH INPUT BUFFER ;PUSHF CLI ;CLEAR INTERUPTS WHILE YOU MOV AX,IFIRST[SI] ;MANIPULATE THE BUFFER POINTERS MOV IAVAIL[SI],AX ;SET AVAIL EQUAL FIRST TO EMPTY STI ;POPF ;ALL DONE AND CLEAR MOV AX,0 ;EVERY TIME YOU FLUSH INPUT BUFFER, MOV ERVAL[SI],AX ;YOU CAN CLEAR THE ERROR BITS DEC AX ;AND RESET THE MOV EROFF[SI],AX ;OFFSET TO ERROR TO AN ILEGAL VALUE JMP IOWNEXT IOWFLO: ;FLUSH OUTPUT BUFFER ;PUSHF CLI ;CLEAR INTERUPTS WHILE YOU MOV AX,OFIRST[SI] ;MANIPULATE THE BUFFER POINTERS MOV OAVAIL[SI],AX ;SET AVAIL EQUAL FIRST TO EMPTY STI ;POPF ;ALL DONE AND CLEAR JMP IOWNEXT IOWTIM: ;LOAD TIMEOUT LIMIT MOV AX,ES:[DI] ;GET NEXT WORD FROM INPUT ADD DI,2 ;SKIP WORD IN COMMAND STRING SUB CX,2 ;COUNT THOSE BYTES OUT OF LOOP JLE IOWERR ;IF THERE WEREN'T ENUF, SCREAM MOV TIMEOUT[SI],AX ;STORE THEM IN STRUCTURE JMP IOWNEXT IOWSEO: ;SET BYTEWISE MIDI OUTPUT/THRU FLAG OR STATUS[SI],OUTHRU ;SET THE OUT/THRU BIT IN STATUS JMP IOWNEXT IOWCLO: ;CLEAR POOR MANS MIDI OPUTPUT/THRU MERGE AND STATUS[SI],NOT OUTHRU ;CLEAR THE BIT JMP IOWNEXT IOWNEXT: LOOP IOWRITE ;LOOP FOR ALL IO CONTROL WRITE BYTES MOV AX,STSDNE ;RETURN 0 FOR SUCCESS JMP EXIT IOWERR: ;I/O CONTROL WRITE ERROR RETURN MOV AX,STSERR OR ERRBSL ;RETURN WRITE FAULT FOR THESE 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: STI ;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 STI 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 STI 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: STI ;POPF ;RE-ENABLE INTERUPTS BEFORE YOU RETURN POP DI POP CX RET GET_IN ENDP SUBTTL INTERUPT SERVICE ROUTINES PAGE ; ; THESE ROUTINES ARE ONLY CALLED WHEN AN INTERUPT IS GENERATED ; BY THE UART. ; 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. MIDI_INT: PUSH AX ;SAVE AX FOR THE USER, MOV AL,020H ;OUTPUT A 20H TO THE UNDOCUMENTED INTERUPT OUT 020H,AL ;CONTROL CHIP. STI ;AND LET THE PROCESSOR INTERUPT ME. PUSH BX ;SAVE THE REST OF THE REGESTERS. PUSH CX PUSH DX PUSH SI PUSH DI PUSH DS ;SAVE THE DATA SEGMENT PUSH CS ;SO YOU CAN LOAD CS POP DS ;INTO DS AND FIND YOUR OWN STRUCTURES. notify I ; ; THE FOLLOWING CODE FIGURES OUT WHICH (IF SEVERAL) DAISY-CHAINED ; DART CHIP FIRED THE INTERUPT, WHICH UART IN THE DART IT WAS, ; AND THE REASON FOR THE INTERUPT (RECEIVE, XMIT, ERROR). ; MOV CX,MIDI_UNITS ;GET THE TOTAL NUMBER OF UARTS MOV SI,OFFSET MIDI_TABA ;ADDRESS OF FIRST UARTS UNIT TABLE INT_LUP: ;HEAD OF LOOP TO CHECK ALL UARTS MOV DX,PORT[SI] ;GET THE PORT ADDRESS ADD DX,MIDCON ;SLIDE UP TO COMMAND/STATUS REGESTER MOV AL,0 ;MAKE SURE WE ARE TALKING TO REGESTER 0 OUT DX,AL JMP SHORT $+2 IN AL,DX ;READ REGESTER 0 STATUS TEST AL,INTPEND ;IS THIS DART CHIP THE ONE? JNE THIS_DART ;YES, GO ON TO FIND THE PORT ADD SI,UNIT_SIZE*2 ;NO, SKIP TWO UARTS TO NEXT WHOLE DART SUB CX,2 JG INT_LUP ;IF THERE ARE ANY LEFT, KEEP TRYING JMP INT_EXIT ;IF NOT, YOU'RE IN TROUBLE, BUT I IGNORE THIS_DART: OR DX,MIDB ;SLIDE UP TO UART B ON THIS DART MOV AL,2 ;SET UP TO READ REGISTER 2 OUT DX,AL JMP SHORT $+2 IN AL,DX ;READ IN VECTOR VALUE TEST AL,VECB ;WAS THIS INTERUPT CAUSED BY UART B? JNE A_INT ;NO, IT MUST BE UART A DEC CX ;YES, MAKE SURE THERE IS A UART B STRUCTURE JCXZ INT_EXIT ;IGNORE INTERUPTS FROM UNUSED UARTS ADD SI,UNIT_SIZE ;GET UART B'S UNIT STRUCTURE JMP INT_REASON ;WE'RE READY TO GO FIND OUT WHY A_INT: AND DX,MIDA ;CONVERT PORT NUMBER BACK TO UART A INT_REASON: AND AX,VECMASK ;WHACK OUT ONLY THE BITS THAT MATTER MOV BX,AX ;PUT IT INTO AN INDEX REGESTER JMP INT_FTAB[BX] ;JUMP TO THE APPROPRIATE ROUTINE ; INT_FTAB DW INT_TXMIT ;TRANSMITTER HOLDING REGESTER EMPTY DW INT_ERROR ;MODEM LINE INTERUPTS NOT IMPLIMENTED DW INT_RECEIVE ;RECEIVER BUFFER HAS A CHARACTER DW INT_ERROR ;RECEIVER FRAMING, OVER-RUN ERROR INT_ERROR: ;ENTRYPOINT FOR SETTING BREAKPOINTS notify E NOP ;FOR ILLEGAL VECTOR VALUES INT_EXIT: MOV DX,PORT[SI] ;GET THE PORT NUMBER AGAIN ADD DX,MIDCON ;CHANGE TO CONTROL PORT AND DX,MIDA ;MAKE SURE IT'S CHANNEL A OF DART MOV AL,ZREINT ;SEND THE SIMULATED Z80 RETURN OUT DX,AL ;FROM INTERUPT COMMAND TO DART ;INTERUPT STUF WAS HERE POP DS ;RECOVER ALL THE REGESTERS POP DI POP SI POP DX POP CX POP BX POP AX IRET ; ; THE FOLLOWING INTERUPT SERVICE ROUTINES ALL HAVE THE ; SAME CONTEXT: ; -CS AND DS POINT TO THE DRIVER SEGMENT. ; -DS:[SI] POINTS TO THE UNIT STRUCTURE FOR THE ASYNC LINE THAT ; FIRED THE INTERUPT. ; -DX POINTS TO THE CONTROL REGESTER OF THE DART ; -AX BX CX 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 PAGE INT_RECEIVE: ;THE PORT HAS RECEIVED A NEW CHARACTER, I MUST COPY IT ;INTO THE INPUT TYPEAHEAD BUFFER. notify R SUB DX,MIDCON ;POINT AT THE DATA REGESTER IN AL,DX ;GET THE CHARACTER CALL PUT_IN ;PUT THE CHARACTER IN THE RING BUFFER CMP AH,0 ;WAS THERE ROOM? JE REC_OK ;NO, SET FLAGS BEFORE RETURNING notify O OR ERVAL[SI],ERIBFO ;NO, SET THE OVERFLOW BIT CMP EROFF[SI],-1 ;IF YOU HAVN'T INDICATED ANY ERRORS YET JNE REC_OK PUSH AX MOV AX,IAVAIL[SI] ;THEN INDICATE THE POSITION THAT THE MOV EROFF[SI],AX ;ERROR HAPPENED POP AX REC_OK: TEST STATUS[SI],OUTHRU ;POOR MANS MIDI MERGE TURNED ON? JZ NEXT_REC ;NOPE, DON'T ECHI THIS CHAR CALL PUT_OUT ;YUP, SEND THE CHARACTER TO OUTPUT CALL START_OUTPUT ;AND START THE TRANSMIT IF NECC. NEXT_REC: ;CHECK TO SEE IF THERE ARE MORE CHARS READY ADD DX,MIDCON ;POINT BACK AT THE COMMAND REGESTER IN AL,DX ;READ REGESTER 0 TEST AL,RXCHAR ;IS THERE ANOTHER CHARACTER READY? JNZ INT_RECEIVE ;YES, GO READ IT IN ALSO MOV AL,ZRXINT ;NO, ENABLE INTERUPTS ON NEXT CHAR OUT DX,AL ;THAT DOES COME IN. JMP INT_EXIT ; ; SUBTTL SPECIAL RECEIVE CONDITION INTERUPT PAGE ; ; PARITY, FRAMING, OR OVERRUN ERROR INTERUPT INT_RXSTAT: notify S MOV AL,1 ;REQUEST READ REGESTER 1 OUT DX,AL JMP SHORT $+2 IN AL,DX ;READ IN THE VALUE AND AX,070H ;CHOP OUT THE ERROR BITS OR ERVAL[DI],AX ;ADD THOSE BITS TO THE ERROR WORD CMP EROFF[SI],-1 ;CHECK TO SEE IF YOU'VE ALREADY JNE RXSTAT_DONE ;TRAPPED ONE UNREPORTED ERROR MOV AX,IAVAIL[SI] ;IF NOT, THEN POINT THE MOV EROFF[SI],AX ;ERROR OFFSET AT NEXT AVAIL BYTE RXSTAT_DONE: MOV AL,ZERRES ;RESET THE ERROR BITS IN THE OUT DX,AL ;UART. 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. notify T AND STATUS[SI],NOT OUTINT ;CLEAR INTERUPT EXPECTED BIT. CALL START_OUTPUT ;START THE NEXT CHARACTER MOV AL,ZTXINT ;RESET THE UART TRANSMITTER OUT DX,AL ;PENDING BIT JMP INT_EXIT ;ROUTINE TO START THE NEXT CHARACTER PRINTING ON THE PORT, 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. ; SI MUST POINT AT THE UNIT STRUCTURE. START_OUTPUT PROC NEAR ;PUSHF ;SAVE THE FLAGS SO I CAN CLI ;DISABLE INTERUPTS TEST STATUS[SI],OUTINT ;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 STATUS[SI],OUTINT ;WARN EVERYBODY THAT I'M BUSY. DONT_START: ;POPF STI RET START_OUTPUT ENDP ;; SUBTTL READ CLOCK CURRENT VALUE PAGE ; ; THE GET_CLOCK ROUTINE RETURNS THE CURRENT CLOCK VALUE ; IN AX. REGESTER DX IS PRESERVED. ; This routine returns the "unsullied" clock value, so beware! The ; timer chip is a count DOWN timer, and you should calculate delta ; values accordingly. The C routines that read this clock invert ; the current value to make it look like an increasing time count, ; but down here in the driver I left the values raw. ; GET_CLOCK PROC NEAR PUSH DX MOV DX,CLOCK_PORT ;GET PORT OF CLOCK CHIP MOV AL,T2 OR LATCH ;TELL HIM YOU WANT TO LATCH TIMER 2 OUT DX,AL JMP SHORT $+2 ADD DX,TIMER2 ;POINT DX AT TIMER2 IN AL,DX ;READ TIMER2 LSB JMP SHORT $+2 MOV AH,AL IN AL,DX ;READ TIMER2 MSB XCHG AH,AL ;SWAP THE BYTES TO NORMAL POP DX RET GET_CLOCK ENDP ; ; ; THE FOLLOWING LABEL DEFINES THE END OF THE DRIVER, SO I ; CAN TELL DOS HOW BIG I AM. MIDI_END: SUBTTL MIDI INITIALIZATION REQUEST ROUTINE PAGE ; ; THE INITIALIZE DRIVER ROUTINES ARE 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 MIDI UNITS THAT THIS DRIVER ; CONTAINS. (APPARENTLY, MSDOS DOESN'T WRITE ANYTHING ON TOP OF ; THIS CODE UNTIL ALL UNITS ARE INITIALIZED. ; THE CONTEXT OF THE INITIALIZE CODE BELOW IS THE SAME AS ; ALL THE OTHER REQUEST ROUTINES EARLIER IN THE DRIVER. ; INIT_TAB DB ZCHANR ;TABLE OF INITIALIZATION BYTES DB 1,W1TXINT OR W1RX1ST OR W1STAT ;ENABLEL XMITR INTS DB 3,W3RXEN OR W3RX8 ;ENABLE RECEIVING, 8 BITS/CHARACTER DB 4,W4STOP1 OR W4X64 ;1 STOP BIT, X64 CLOCK MODE DB 5,W5TXEN OR W5TX8 ;8 BITS/CHARACTER ON INPUT DB ZRXINT ;ALLOW NEXT CHAR INPUT TO INTERUPT INIT_SIZE EQU $-INIT_TAB ;COUNT THE BYTES FOR ME ; ; TABLE OF REGESTER OFFSETS AND VALUES FOR INITIALIZING THE CLOCK CLK_TAB DB 0,T1 OR LMSB OR RATE ;TIMER ONE IS A RATE GENERATOR DB TIMER1,0,0,8 ;THAT DIVIDES CLOCK BY 2048 (800H) DB -TIMER1,T2 OR LMSB OR RATE ;TIMER TWO IS ALSO A RATE GENERATOR DB TIMER2,0FFH,0,0FFH ;THAT DIVIDES BY THE LARGEST INT. DB -TIMER2,T3 OR LMSB OR RATE ;TIMER 3 JUST COUNTS DOWN DB TIMER3,0FFH,0,0FFH ;FROM LARGEST INTEGER (64K) CLK_SIZE = $-CLK_TAB ;SIZE OF THIS TABLE ; ; INITIALIZE THE DRIVER AND DEVICE ; MIDI_INIT: MOV AX,OFFSET MIDI_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 DX,PORT[SI] ;GET THE PORT ADDRESS OF THIS LINE ADD DX,MIDCON ;SLIDE UP TO THE COMMAND REGESTER ; THE FOLLOWING CODE INITIALIZES THE Z8470 DART ; FOR INTERUPT DRIVEN MIDI OPERATION MOV BX,OFFSET INIT_TAB ;GET ADDRESS OF TABLE MOV CX,INIT_SIZE ;SIZE OF TABLE INIT_PORT: MOV AL,[BX] ;GET NEXT PORT CONTROL BYTE OUT DX,AL ;SEND IT TO CONTROL REGESTER JMP SHORT $+2 INC BX ;INCRIMENT TO NEXT BYTE LOOP INIT_PORT ;LOOP UNTIL DONE TEST DX,MIDB ;IF THIS IS UART B OF THE DART, JNE DONE_INIT ;THEN YOU ARE DONE ;ONLY ONCE PER DART IS IT NESESSARY TO INITIALIZE ;THE VECTOR IN REGESTER 2 OR DX,MIDB ;SLIDE UP TO UART B MOV AL,2 ;AND THEN INITIALIZE THE OUT DX,AL ;WRITE REGESTER 2 WITH JMP SHORT $+2 MOV AL,0 ;A ZERO VECTOR NUMBER OUT DX,AL ;IT'S ONLY NECESSARY TO INITIALIZE THE INTERUPT ;VECTOR AND MASK ONCE, BUT I ALLOW THE FOLLOWING ;CODE TO EXECUTE ONCE FOR EVERY DART CHIP ON YOUR ;BOARD. IT CAN'T HURT. MOV AX,0 ;POINT ES AT THE VECTOR SEGMENT MOV ES,AX ;SO CAN INITIALIZE THE VECTORS MOV AX,OFFSET MIDI_INT ;GET ADRS OF INTERUPT SERVICE ROUTINE MOV DI,MIDI_VEC ;GET ADRS OF VECTOR STOS WORD PTR [DI] ;STORE THE OFFSET THERE, THEN MOV ES:[DI],CS ;THE SEGMENT IN THE FOLLOWING WORD. MOV CX,DI ;CALCULATE 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 JMP SHORT $+2 AND AL,AH ;AND MY BIT OUT OF IT, OUT 021H,AL ;WRITE IT BACK OUT AGAIN. ; ; THIS CODE INITIALIZES THE ON-BOARD CLOCK CHIP TO USEFUL ; MODES AND RATES FOR MIDI USE. TIMER1 IS USED TO DIVIDE THE CLOCK ; PULSE DOWN BY 2048 TO A 1024 TICKS PER SECOND (ABOUT 1 MILISECOND) ; RATE. THAT RATE FEEDS TIMER2 WHICH IS THE FIRST CLOCK VALUE READ. ; FOR LONG DELAY PERIODS, TIMER2 IS ASSUMED TO FEED TIMER3, SO IT ; WILL CONTAIN THE OVERFLOW, ALLOWING COUNTS UP TO 137 YEARS! ; MOV DX,CLOCK_PORT ;GET CLOCK CONTROL REGESTER PORT MOV BX,OFFSET CLK_TAB ;GET ADDRS OF TABLE OF COMMANDS MOV CX,CLK_SIZE/2 ;SEND THIS MANY COMMANDS TO CLOCK ; SAR CX,1 CLK_LUP: MOV AL,[BX] ;GET NEXT REGESTER OFFSET CBW ADD DX,AX ;AND OFFSET FROM IT INC BX ;SLIDE UP TO NEXT VALUE MOV AL,[BX] ;GET IT, AND INC BX ;DON'T FORGET TO SKIP PAST OUT DX,AL ;SEND VALUE TO CLOCK REGESTER LOOP CLK_LUP ; THE FOLLOWING LOOP IS SUGESTED BY INTEL IN THE ; CLOCK CHIP SPEC.'S TO MAKE SURE THE CLOCK HAS ; SETTLED BEFORE YOU FIRST READ IT. I ONLY WATCH ; TIMER2 SETTLE, AND ASSUME THE REST ARE LONG GONE MOV DX,CLOCK_PORT ;MAKE SURE YOU'RE LOOKING AT CONTROL CLK_START: MOV AL,T2 OR LATCH ;LATCH TIMER TWO OUT DX,AL JMP SHORT $+2 ADD DX,TIMER2 ;SLIDE UP TO IT'S DATA REGESTER IN AL,DX ;READ AND JMP SHORT $+2 MOV AH,AL ;SAVE LEASTMOST BYTE IN AL,DX ;READ MOST SIGNIFICANT BYTE SUB DX,TIMER2 ;SLIDE BACK TO CONTROL REGESTER XCHG AL,AH ;MAKE INTO A BINARY NUMBER NOT AX ;REVERSE INTO A UP-COUNTING NUMBER OR AX,AX ;AND CHECK FOR ZERO JNZ CLK_START ;WAIT FOR IT TO SETTLE DOWN DONE_INIT: MOV AX,STSDNE ;RETURN NO ERRORS. JMP EXIT DRIVER ENDS END