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Assembly Source File | 1995-07-23 | 23.3 KB | 997 lines

PAGE 60,132 NAME UART TITLE UART Version 1.2 1993 June 17 COMMENT √ UART C: Detect UART type of serial port UART COM1: If Errorlevel 5 GoTo SyntaxError If Errorlevel 4 GoTo PS2TYPE3 If ErrorLevel 3 GoTo AT16550FIFO If ErrorLevel 2 GoTo AT16450 If ErrorLevel 1 GoTo XT8250 If ErrorLevel 0 GoTo NoSuchPort UART by itself is considered a syntax error and generates a usage message. Sets errorlevel to type of UART detected. This code is based on the MASM routines on page 364 Of PC Magazine May 26, 1992. In DESQview often ports COM1: and COM2: are not accessible. You must have access priviledge in your PIF. Under OS/2 virtualization makes all com ports look like 8250s. Supports only COM1: .. COM4:. Looks in BIOS Table to find the corresponding physical addresses. It expects this pattern COM1: COM2: COM3: COM4: port: 3f8 2f8 3e8 2e8 irq: 4 3 4 3 int: C B C B If for example COM1: has port 2f8, then irq 3 would be anticipated and its interrupts would be fielded on int vector B. Port has precedence over com port number in determining irq. To Do - extend support to COM5..COM8 I don't know the expected IRQs or port addresses for these beasts. If you have info on how these are supposed to work, please pass it along. Also I would need someone with a machine with such ports to beta test. √ ; end of comment ;====== ; M A C R O S PEEK MACRO portoffset ;; read port then delay if (portoffset NE DITTO) lea dx,[bx+portoffset] endif in al,dx call breath ENDM POKE MACRO portoffset ;; write port then delay if (portoffset NE DITTO) lea dx,[bx+portoffset] endif out dx,al call breath ENDM ;====== ; E Q U A T E S PIC EQU 21h ; 21h PIC interrupt controller ; bits 76543210 - 1-disable interrupt RBR EQU 0 ; 3F8 Receive Buffer Register THR EQU 0 ; 3F8 Transmit Holding Register LSBDIV EQU 0 ; 3F8 LSB divisor, latch bit must be on ; in the LCR IER EQU 1 ; 3F9 Interrupt Enable Register ; 0000MLTR 1=enable ; Modem status, Line, Transmit, Receive MSBDIV EQU 1 ; 3F9 MSB divisor, DBLAB bit must be on IIR EQU 2 ; 3FA Interrupt Ident Register ; 001 none ; 110 line error, read line status ; 100 data avail, read char ; 010 thr empty, read IIR, send char ; 000 modem status, read MSR FIFO EQU 2 ; 3FA Fifo Control Register LCR EQU 3 ; 3FB Line Control Register ; DBSEPSWW ; Divisor latch, Break, Stick, Even ; Parity, Stop bits, word length11=8 MCR EQU 4 ; 3FC Modem Control Register ; 000L21RD ; Loopback, Out-2, Out-1, RTS, DTR ; Out-2 enables ints, Out-1 does reset LSR EQU 5 ; 3FD Line Status Register ; 0THBFPOD ; Tx shift, Tx Hold, Break, Frame, Parity, ; Overrun, Data ready MSR EQU 6 ; 3FE Modem Status Register ; SRDCSRDC ; line Signal, Ring, DSR, CTS ; delta line Signal, Ring, DSR, CTS SCR EQU 7 ; 3FF Scratch ENH EQU 8003h ; 83FB Enhanced register DITTO EQU 9999 ; use same port as previously. stack segment stack ; keep MS link happy by providing null stack stack ends ;============================================================== CODE SEGMENT PARA ; start off in code. ;============================================================== data segment word ; provide a separate DATA segment ; Even though it appears in the source ; before the code, it the COM file it ;============================================= BIOSDATA segment AT 40h ; dummy segment in low RAM org 0h BIOSComAddrs dw ? ; 4 words of COM1: .. COM4: dw ? ; device addresses dw ? dw ? BIOSDATA ends ;============================================= ; E R R O R M E S S A G E S ;============================================= CopyrightMsg label byte db 13,10 db '░▒▓█ UART 1.2 █▓▒░',13,10 db 13,10 db 'Determines UART type on specified COM port.',13,10 db 13,10 DB '(c) Copyright Roedy Green Canadian Mind Products 1992,1993.',13,10 DB '#601 - 1330 Burrard Street, Vancouver BC CANADA V6Z 2B8 (604) 685-8412',13,10 db 'May be freely distributed and used for any purpose except military.',13,10 db 13,10,'$' UsageMsg label Byte db 'Error in command line. Note the mandatory colon. Try:',13,10 db 13,10 db 'UART COM1:',13,10 db 'If Errorlevel 5 GoTo SyntaxError',13,10 db 'If Errorlevel 4 GoTo PS2TYPE3',13,10 db 'If ErrorLevel 3 GoTo AT16550FIFO',13,10 db 'If ErrorLevel 2 GoTo AT16450',13,10 db 'If ErrorLevel 1 GoTo XT8250',13,10 db 'If ErrorLevel 0 GoTo NoSuchPort',13,10,'$' PortMsg db "COM" PortPatch1 db "x: is at hex port address: " HexPatch1 db "xxxx.",13,10,'$' ; Messages to describe the various types of chip found. code0 db "Port not accessible or not installed.",13,10,'$' code1 db "XT style 8250 UART.",13,10,'$' code2 db "AT style 16450 unbuffered UART (might possibly be old-style 16550 or 8250a).",13,10,'$' code3 db "AT style 16550AF buffered FIFO UART",13,10,'$' code4 db "PS/2 style IBM type 3 DMA serial port",13,10,'$' WrongPortMsg db "Warning, COM" portpatch2 db "x: should be at hex port address: " HexPatch2 db "xxxx. ",13,10,'$' GoodIRQmsg db "Port correctly configured to IRQ " IrqPatch1 db "x.",13,10,'$' BadIRQMsg db "ERROR: port not properly configured to IRQ " IrqPatch2 db "x.",13,10 db 13,10 db "If the port appears to be configured correctly, retry the UART test",13,10 db "but first try one or more of the following:",13,10 db 13,10 db " 1. Remove any external devices (e.g. modems or serial mice)",13,10 db " connected to the COM ports.",13,10 db 13,10 db " 2. Install a loopback plug on the COM port under test.",13,10 db 13,10 db " 3. Boot from a floppy disk you are sure installs no drivers on the COM ports.",13,10,"$" ConfusedIRQMsg db "WARNING: another port sharing IRQ " IrqPatch3 db "x or driver software",13,10 db " is interfering with this test.",13,10,"$" DescList dw offset COM:code0 dw offset com:code1 dw offset com:code2 dw offset com:code3 dw offset com;code4 ExpectedList dw 3f8h ; expected port address for COM1 dw 2f8h ; COM2 dw 3E8h ; COM3 dw 2e8h ; COM4 OldVect dd 0 ; CS:IP of current interrupt vector OldPIC db 0 ; old value of PIC interrupt enable reg. OldIER db 0 ; old value of Interrupt Enable Register OldMCR db 0 ; old value of Modem Control Register OldLCR db 0 ; old value for Line Control Register OldLSBDivisor db 0 ; old value of latch baud rate divisor OldMSBDivisor db 0 ; " MSB OldScr db 0 ; old value of Scratch register OldENH db 0 ; old value of Enhance register 1 ComNo dw 0 ; 0=COM1: 1=COM2: Comaddr dw 0 ; 3F8=COM1: 2F8=COM2: 3E8=COM3: 2E8=COM4: IRQ db 0 ; 3 or 4, corresponds to int B or C. Vector db 0 ; B or C interrupt vector EventCount dw 0 ; counts how many interrupts. Should be one. data endS ;============================================================== com group code,data ASSUME CS:COM,DS:COM,ES:COM ORG 100H Start: Call Parse ; prepare the command line Call Analyse ; analyse the command line for drive letter mov bx,ComAddr ; hex port address for com port Call UartType ; return code in bx push bx Call DisplayUARTType ; message to describe type we found. Call CheckPort ; check if port is one expected Call CheckIRQ ; Check that IRQ is one expected ; This code does not work yet. pop bx mov al,bl mov ah,04ch ; exit to dos, errorlevel in AL int 21h Failed: lea dx,Copyrightmsg call say lea dx,usagemsg call say mov ax,4c05h ; exit back to DOS with error code 5 int 21h ;============================================================== UARTTYPE Proc Near ; on entry BX is serial I/O port: e.g. 3F8 ; On exit BX contains the serial port type ; This code is very similar to code in PC Magazine page 364 ; May 26, 1992. I added two null checks and tighted up the code. ; 0=not present, and sets carry ; 1=8250 ; 2=16450, old style 16550, 8250A ; 3=16550AF with FIFO queues ; 4=IBM type 3 serial port with DMA ; trashes bx,cx,dx test bx,bx jz isNullComm Call SaveChipState cli ; port might be in use, e.g. mouse ; attempt to do as little damage as possible. mov al,00000011b ; set up a vanilla n81 setting POKE LCR ; 3FB attempt to write to line control register PEEK DITTO ; see if it took sti cmp al,00000011b jne isNullComm ; no, must be no port at all. PEEK MCR ; 3FC modem control reg and al,11110011b ; disable serial interrupt ; Out-2 must be on for interrupts to happen ; out-1 does a reset ; Where is this documented? POKE DITTO cli mov al,55h ; see if scratch register exists POKE SCR PEEK DITTO ; see if 55 comes back. sti cmp al,55h jne is8250 ; 8250 has no scratch reg mov al,0aah ; just in case, try that again cli POKE DITTO PEEK DITTO sti cmp al,0aah jne is8250 ; 8250 has no scratch reg ; must be something more advanced than the 8250 mov al,7 ; attempt to enable FIFOs cli POKE FIFO ; 3FA PEEK IIR ; 3FA interrupt id reg sti and al,0c0h ; strip out all but FIFO bits jz Is16450 ; all 0 if no FIFO. ; must be more advanced than the 16450 cli PEEK ENH ; 83FB read enhanced register 1 or al,01000000b ; enable DMA Xmit mode POKE DITTO PEEK IIR sti and al,0c0h ; mask all but FIFO ID cmp al,040h jne Is16550 jmp IsIBMType3 IsNullComm: mov bx,0 stc ret Is8250: mov cx,1 jmp UARTTypeDone Is16450: mov cx,2 jmp UARTTypeDone Is16550: mov cx,3 jmp UARTTypeDone IsIBMType3: mov cx,4 UARTTypeDone: Call RestoreChipState mov bx,cx clc ret UARTTYPE EndP ;============================================= DisplayUARTType Proc Near ; on entry BX is the type code for the UART type. ; we display a message describing it. ; trash everything push bx mov ax,Comaddr ; get hex address call AsHex ; patch in the hex address to the ; output message. lea si,AsHexBuf lea di,HexPatch1 movsw movsw mov ax,ComNo ; 0=COM1: 1=COM2: add al,'1' mov PortPatch1,al ; patch com port number in message. lea dx,PortMsg ; echo port number and address. call Say pop bx shl bx,1 ; index table of words mov dx,DescList[BX] Call Say ; display corresponding description ret DisplayUARTType EndP ;============================================================== CheckPort Proc Near ; check that ComPort is usual value for this ComNo. ; If not, print a warning message. ; Presume Comaddr has been calculated already. ; trash everything test Comaddr,-1 jz UsingProperPort ; if not in use, don't count as error. mov bx,ComNo shl bx,1 mov bx,ExpectedList[bx] ; expect comport # cmp bx,ComAddr je UsingProperPort ; Oops, this is not the port we would usually use mov ax,bx call AsHex ; patch in the hex address to the ; output message. lea si,AsHexBuf lea di,HexPatch2 movsw movsw mov ax,ComNo ; 0=COM1: 1=COM2: add al,'1' mov PortPatch2,al ; patch com port number in message. lea dx,WrongPortMsg ; echo port number and address. call Say UsingProperPort: ret CheckPort EndP ;============================================================== SaveChipState Proc Near ; Save values of UART registers so we can restore later mov dx,PIC ; save state of PIC in al,dx mov OldPIC,al mov bx,ComAddr ; e.g 3F8 PEEK MCR ; 3FC save current modem control reg. mov OldMCR,al PEEK IER ; 3F9 save current interrupt enable register mov OldIER,al PEEK LCR ; 3FB save current line control register mov OldLCR,al PEEK SCR ; 3FF save old scratch register mov oldSCR,al PEEK ENH ; 83FB save old enhanced reg1 mov oldENH,al mov al,10000011b ; set up n81, access divisor POKE DITTO PEEK LSBDIV ; save old baud rate divisor mov OldLSBDivisor,al PEEK MSBDIV mov OldMSBDivisor,al mov al,OldLCR ; 3FB just save LCR, don't change it yet. POKE LCR ret SaveChipState EndP ;============================================= RestoreChipState Proc Near ; put all registers in chip back the way they were. cli ; restore PIC back the way it mov dx,PIC ; was. Non 3/4 IRQs may have legitimately in al,dx ; changed during our run. We don't put them and al,0e7h ; back, just irq 3/4. mov ah,OldPic ; 0=enabled 1=disabled and ah,018h or al,ah out dx,al sti mov bx,ComAddr ; e.g 3F8 mov al,OldIER ; 3F9 restore interrupt enable register 3F9 POKE IER mov al,OldMCR ; 3FC restore original modem control register 3FC POKE MCR mov al,oldSCR POKE SCR ; 3FF restore old scratch register mov al,oldENH POKE ENH ; 83FB restore old enhanced reg1 mov al,10000011b ; set up n81, access divisor POKE LCR ; 3FB restore divisor mov al,OldLSBdivisor POKE LSBDIV mov al,OldMSBDivisor POKE MSBDIV mov al,OldLCR ; 3FB restore line status register POKE LCR ; we cannot directly restore the IIR ; but we can turn off the FIFO mov al,0 POKE FIFO ; 3FA ret RestoreChipState EndP ;============================================= ;COMMENT √ ; this routine does not work yet. WHY??? ; I have chewed on this for days!!! CheckIRQ Proc Near ; Check the that exactly one interrupt at the expected IRQ Call CalcIRQ ; figure out which IRQ should be used Call SetTrap ; trap interrupts from expected IRQ Call Trigger1Int ; Trigger 1 interrupt using loopback Call RestoreIRQ ; put trap back the way it was Call PatchIRQ ; patch expected IRQ # into error messages. cmp Eventcount,1 ; should see 1 int jb BadIRQ ja ConfusedIRQ ; Just right, saw 1 interrupt GoodIRQ: lea dx,GoodIRQMsg call Say ret BadIRQ: lea dx,BadIRQMsg call Say ret ConfusedIRQ: lea dx,ConfusedIRQMsg call Say ret CheckIRQ EndP ;============================================================== CalcIRQ Proc Near ; Calculate the IRQ 4 or 3 to match hex address mov ax,ComAddr lea di,Expectedlist ; scan list of legal port #s mov cx,4 ; to make sure it is in the list. repne scasw jne NoIrq ; ax still has the address. mov al,ah ; 3f8 2f8 3e8 2e8 -> 2 or 3 sub ah,ah inc ax ; 3 -> 4 2 -> 3 mov IRQ,al add al,8 ; 3->B 4->C mov Vector,al ; which interrupt vector, ; not same as IRQ clc ret NoIRQ: mov IRQ,0 mov Vector,0 stc ret CalcIRQ EndP ; ============================================= PatchIRQ Proc Near ; Patch expected the IRQ number into various possible error messages. mov al,IRQ ; 3 or 4 binary add al,030h ; 3 or 4 ASCII mov IrqPatch1,al mov IrqPatch2,al mov IrqPatch3,al ret PatchIRQ EndP ; ============================================= ASSUME DS:nothing,ES:nothing SetTrap Proc near ; Trap interrupts from the expected source irq 3 or 4. push DS push ES mov ah,35h mov al,Vector ; save old B/C vector int 21h ; result in ES:BX mov word ptr OldVect, bx mov word ptr OldVect+2, ES pop ES push CS pop DS lea dx,CS:IntHandler mov ah,25h mov al,Vector ; set up new B/C vector to point to our ; miniature handler int 21h pop DS ret SetTrap EndP ; ============================================= ASSUME DS:NOTHING,ES:NOTHING IntHandler Proc Near ; Interrupt handler for irq 3 or 4 int B or C. ; ints are off right now push ax ; must not disturb ANYTHING! push bx push cx push dx inc CS:EventCount ; only CS: works, ; count how many interrupts. ; should be only one. mov al,20h out 20h,al ; send eoi command to PIC call Breath Call ClearPendingInterrupt sti pop dx pop cx pop bx pop ax iret IntHandler EndP ;============================================= ASSUME DS:COM,ES:COM Trigger1Int Proc Near ; Trigger one interrupt and count how many ints appeared at the ; expected interrupt. Call SaveChipState ; save current values of all regs we will wreck. mov al,10000011b ; set up n81, access divisor POKE LCR ; 3FB mov al,030h POKE LSBDIV ; set up 2400 baud mov al,0 POKE MSBDIV mov al,00000011b ; set up n81, access regular regs POKE LCR ; 3FB cli ; Turn on ints 3 and 4 in the PIC mov dx,PIC in al,dx and al,0e7h ; 0=enabled 1=disabled. out dx,al sti mov al,0 ; disable any FIFOs POKE FIFO ; 3FA mov al,00000110b ; enable interrupts, just THR empty & overrun POKE IER ; 3F9 Some pending interrupt might trigger ; Loopback does not work. IBM does not let the PIC see the ; interrupts in loopback mode. mov al,00001000b ; out-1 does a reset of attached modem ; must clear ; out-2 enables interrupts ; turn off DTR and RTS, to reset ; any attached modem POKE MCR ; 3FC might generate an interrupt call BigBreath mov al,00001011b ; out-1 does a reset of attached modem ; must clear ; out-2 enables interrupts ; turn on DTR and RTS POKE MCR ; 3FC might generate an interrupt call BigBreath mov EventCount,0 ; clear interrupt counter sti ; ints should be on anyway. mov al,0 ; send a null character POKE THR ; Five things can happen: ; 1. device accepts the char ; 2. device keeps CTS low, so char ; never goes out. We never get an int. ; 3. device is powered off or missing. ; Then we get a line status int. ; 4. IRQ not set properly. We see no int. ; 5. Some other device is using same IRQ. ; We see multiple ints. Call BigBreath ; Wait long enough for interrupt to happen call ClearPendingInterrupt Call RestoreChipState ret Trigger1Int EndP ;============================================= ClearPendingInterrupt Proc Near ; If there is a pending interrupt, get it cleared ; See page 1-242 XT tech ref. ; trashes ax,bx,dx ; Called from Int handler. Cannot use DS: mov bx,CS:ComAddr ; e.g 3F8 PEEK IIR ; 3FA read IIR to clear ; any modem transmitter holding empty interrupt PEEK RBR ; 3F8 read receive buffer register to clear ; any char in interrupt PEEK LSR ; e.g. 3FD read line status register to clear ; any parity interrupt PEEK MSR ; e.g. 3FE read modem status register to clear ; any modem status interrupt ret ClearPendingInterrupt EndP ;============================================= ASSUME DS:NOTHING,ES:NOTHING RestoreIRQ proc near ; Put the B/C vector back the way it was push DS mov dx,word ptr OldVect mov ax,word ptr OldVect+2 mov DS,ax mov ah,25h mov al,Vector ; set B/C vector int 21h pop DS ret RestoreIRQ EndP ; end of commented out code ASSUME DS:COM,ES:COM ;============================================= ; C O M M A N D L I N E P A R S I N G R O U T I N E S ;============================================= MLeading PROC Near ; Remove leading blanks ; on entry ES:BX is addr of string, CX its length ; trims off any leading blanks, leaving result in BX CX ; length may also be 0 or 1, but not -ve ; If the entire string is blank the result is the null string mov di,bx mov al,20H ; AL = blank -- the search char jcxz mleading2 ; jump if null string repe scasb ; scan ES:DI forwards till hit non blank ; DI points just after it (wrap ok) ; cx IS ONE TOO SMALL, OR 0 IF NONE FOUND je mleading1 ; jump if entire string was blank inc cx ; CX is length of remainder of string mleading1: dec di ; DI points to non-blank mleading2: mov bx,di ; put address back ret MLeading ENDP ;======================================== MTrailing PROC Near ; Remove trailing blanks. ; on entry ES:BX is addr of string, CX its length ; trims off any trailing blanks, leaving result in BX CX ; length may also be 0 or 1, but not -ve ; If the entire string is blank the result is the null string mov di,bx add di,cx ; calc addr last char in string dec di mov al,20H ; AL = blank -- the search char jcxz mtrailing1 ; jump if null string std repe scasb ; scan ES:DI backwards till hit non blank ; DI points just ahead of it (wrap ok) ; CX is one too small, or 0 if none found cld je mtrailing1 ; jump if whole string was blank inc cx mtrailing1: ret MTrailing ENDP ;======================================== Parse PROC NEAR ; Parse the command line to remove lead/trail blanks from ; the single drive parameter and terminate it by 2 nulls. ; sample inputs ; UART COM1: ; UART COM2: ; UART ; ES: points to PSP ; When Done ES:BX points to start of string. ; String will be terminated by 2 nulls ; CX counts bytes in string exclusive of nulls ; counted string at HEX 80 PSP ; contains command line. ; Preceeded by unwanted spaces. ; possibly followed by unwanted spaces. ; currently missing a trailing null. xor ch,ch mov cl,es:[80H] mov bx,81H call Mleading ; get rid of leading blanks call MTrailing ; get rid of trailing blanks mov di,bx ; calc addr of byte just past end add di,cx mov word ptr ES:[di],0 ; plop in pair of nulls after string ret Parse ENDP ;====================================== Analyse PROC NEAR ; analyses the command line allowing COM1: COM2: ; On entry ES:BX points to start of string. ; String will be terminated by 2 nulls ; CX counts bytes in string exclusive of nulls ; lead/trail spaces are gone. jcxz BadCmd ; was no command cmp cx,5 ; COM1: - must be 5 chars jne BadCmd mov al,ES:[bx+4] cmp al,':' ; make sure last char is : jne BadCmd mov al,ES:[bx+3] sub al,'1' ; '1'->0 '2'->1 '3'->2 '4'->3 cmp al,3 ja BadCmd ; allow only COM1: to COM4: mov Byte Ptr ComNo,AL push ES mov ax,BIOSDATA ; convert to port address mov es,ax ASSUME ES:BIOSDATA mov di,word Ptr ComNo shl di,1 ; address a table of words it low RAM mov ax,ES:BIOSComAddrs[di] ASSUME ES:COM pop ES mov ComAddr,ax AnalDone: RET BadCmd: Jmp Failed Analyse ENDP ;============================================= AsHex Proc Near ; calculates 4 digit (16 bits) hex number in AX ; get digits into place, don't worry about excess high order stuff. ; leaves result in AsHexBuf mov AsHexBuf+3,al mov cx,4 shr al,cl mov AsHexBuf+2,al mov AsHexBuf+1,ah shr ah,cl mov AsHexbuf+0,ah lea si,AsHexBuf mov cx,4 AsHexLoop: lodsb ; fix up each character in turn and al,0Fh cmp al,0Ah jle IsDigit add al,'A'-0ah jmp SaveDigit IsDigit: add al,'0' SaveDigit: mov [si-1],al ; lodsb incremented si already loop AsHexLoop ret Data segment AsHexBuf db '0000$' Data Ends AsHex EndP ;============================================= Say Proc Near ; on entry DX points to a string to display on screen MOV AH,9 Int 21h ret Say EndP ;======================================= BigBreath Proc Near ; Wait a decent length of time for triggered interrupt to happen. push cx mov cx,20d ; nested wait loop wait1: push cx mov cx,60000d wait2: loop Wait2 pop cx loop Wait1 pop cx ret BigBreath EndP ;======================================= Breath Proc Near ; Take a breath between pokes to the UART chip to give it time to ; recover ready for next i/o command. JMP $+2 is a little too tight. push cx mov cx,10d wait3: loop Wait3 pop cx ret Breath EndP ;======================================= CODE ends end start