; Generic MS DOS Kermit module

; Added global entry point vtstat for use by Status in mssset.
; Added safety warning in prtchr.
; Also trimmed off trailing commas in publics. Joe R. Doupnik 12 March 1986

        public  serini, serrst, clrbuf, outchr, coms, vts, vtstat, dodel
        public  ctlu, cmblnk, locate, lclini, prtchr, dobaud, clearl
        public  dodisk, getbaud, beep
        public  count, xofsnt, puthlp, putmod, clrmod, poscur
        public  sendbr, term, machnam, setktab, setkhlp, showkey
        include mssdef.h

false   equ     0
true    equ     1
instat  equ     6
rddev   equ     3fH
open    equ     3dH

; external variables used:
; drives - # of disk drives on system
; flags - global flags as per flginfo structure defined in pcdefs
; trans - global transmission parameters, trinfo struct defined in pcdefs
; portval - pointer to current portinfo structure (currently either port1
;    or port2)
; port1, port2 - portinfo structures for the corresponding ports

; global variables defined in this module:
; xofsnt, xofrcv - tell whether we saw or sent an xoff.

datas   segment public 'datas'
        extrn   drives:byte,flags:byte, trans:byte
        extrn   portval:word, port1:byte, port2:byte

machnam db      'Generic MS-DOS 2.0$'
erms20  db      cr,lf,'?Warning: System has no disk drives$' ; [21a]
erms40  db      cr,lf,'?Warning: Unrecognized baud rate$'
erms41  db      cr,lf,'?Warning: Cannot open com port$'
erms50  db      cr,lf,'Error reading from device$'
hnd1    db      cr,lf,'Enter a file handle.  Check your DOS manual if you are '
        db      cr,lf,'not certain what value to supply (generally 3).$'
hnd2    db      cr,lf,'Handle: $'
hnderr  db      cr,lf,'Warning: Handle not known.'
deverr  db      cr,lf,'Any routine using the communications port will'
        db      cr,lf,'probably not work.$'
hndhlp  db      cr,lf,'A four digit file handle $'
dev1    db      cr,lf,'Device: $'
devhlp  db      cr,lf,'Name for your systems auxiliary port $'
badbd   db      cr,lf,'Unimplemented baud rate$'
noimp   db      cr,lf,'Command not implemented.$'
shkmsg  db      'Not implemented.'
shklen  equ     $-shkmsg
setktab db      0
setkhlp db      0
crlf    db      cr,lf,'$'
delstr  db      BS,' ',BS,'$'           ; Delete string. [21d]
clrlin  db      cr,'$'                  ; Clear line (just the cr part).
clreol  db      '^U',cr,lf,'$'          ; Clear line.
telflg  db      0               ; non-zero if we're a terminal.
xofsnt  db      0               ; Say if we sent an XOFF.
xofrcv  db      0               ; Say if we received an XOFF.
count   dw      0               ; Number of chars in int buffer.
prthnd  dw      0               ; Port handle.
prttab  dw      com2,com1
com1    db      'COM1',0
com2    db      'COM2',0
tmp     db      ?,'$'
temp    dw      0
temp1   dw      ?               ; Temporary storage.
temp2   dw      ?               ; Temporary storage.
rdbuf   db      20 dup(?)       ; Buffer for input.
prtstr  db      20 dup(?)       ; Name of auxiliary device. [27d]

; Entries for choosing communications port. [19b]
comptab db      6               ; Number of options
        mkeyw   '1',01H
        mkeyw   '2',00H
        mkeyw   'COM1',01H
        mkeyw   'COM2',00H
        mkeyw   'DEVICE',02H
        mkeyw   'FILE-HANDLE',03H

ourarg  termarg <>

datas   ends

code    segment public
        extrn   comnd:near, dopar:near, prserr:near, atoi:near, prompt:near
        assume  cs:code,ds:datas

; this is called by Kermit initialization.  It checks the
; number of disks on the system, sets the drives variable
; appropriately.  Returns normally.

DODISK  PROC    NEAR
        mov ah,gcurdsk                  ; Current disk value to AL.
        int dos
        mov dl,al                       ; Put current disk in DL.
        mov ah,seldsk                   ; Select current disk.
        int dos                         ; Get number of drives in AL.
        mov drives,al
        ret
DODISK  ENDP

; Clear the input buffer. This throws away all the characters in the
; serial interrupt buffer.  This is particularly important when
; talking to servers, since NAKs can accumulate in the buffer.
; Do nothing since we are not interrupt driven.  Returns normally.

CLRBUF  PROC    NEAR
        ret
CLRBUF  ENDP

; Clear to the end of the current line.  Returns normally.

CLEARL  PROC    NEAR
        mov ah,prstr
        mov dx,offset clreol
        int dos
        ret
CLEARL  ENDP

; Put the char in AH to the serial port.  This assumes the
; port has been initialized.  Should honor xon/xoff.  Skip returns on
; success, returns normally if the character cannot be written.

outchr: mov bp,portval
        cmp ds:[bp].floflg,0    ; Are we doing flow control.
        je outch2               ; No, just continue.
        xor cx,cx               ; clear counter
outch1: cmp xofrcv,true         ; Are we being held?
        jne outch2              ; No - it's OK to go on.
        loop outch1             ; held, try for a while
        mov xofrcv,false        ; timed out, force it off and fall thru.
outch2: push dx                 ; Save register.
        mov al,ah               ; Parity routine works on AL.
        call dopar              ; Set parity appropriately.
        mov dl,al
        mov ah,punout           ; Output char in DL to comm port.
        int dos
        pop dx
        jmp rskp

; This routine blanks the screen.  Returns normally.

CMBLNK  PROC    NEAR
        mov ah,prstr
        mov dx,offset crlf      ; Can't do anything else.
        int dos
        ret
CMBLNK  ENDP

; Homes the cursor.  Returns normally.

LOCATE  PROC    NEAR
        mov dx,0                ; Go to top left corner of screen.
        jmp poscur
LOCATE  ENDP

; Write a line at the bottom of the screen...
; the line is passed in dx, terminated by a $.  Returns normally.
putmod  proc    near
        push    dx              ; preserve message
        mov     dx,1800h        ; now address line 24
        call    poscur
        pop     dx              ; get message back
        mov     ah,prstr
        int     dos             ; write it out
        ret                     ; and return
putmod  endp

; clear the mode line written by putmod.  Returns normally.
clrmod  proc    near
        mov     dx,1800h
        call    poscur          ; Go to bottom row.
        call    clearl          ; Clear to end of line.
        ret
clrmod  endp

; Put a help message on the screen.
; Pass the message in ax, terminated by a null.  Returns normally.
puthlp  proc    near
        push    ax              ; preserve this
        mov     ah,prstr
        mov     dx,offset crlf
        int     dos
        pop     si              ; point to string again
puthl3: lodsb                   ; get a byte
        cmp     al,0            ; end of string?
        je      puthl4          ; yes, stop
        mov     dl,al
        mov     ah,dconio
        int     dos             ; else write to screen
        jmp     puthl3          ; and keep going
puthl4: mov     ah,prstr
        mov     dx,offset crlf
        int     dos
        ret
puthlp  endp

; Set the baud rate for the current port, based on the value
; in the portinfo structure.  Returns normally.

DOBAUD  PROC    NEAR
        mov ah,prstr
        mov dx,offset noimp     ; Say it's not implemented.
        int dos
        mov bx,portval
        mov [bx].baud,0FFFFH    ; So it's not a recognized value.
        ret                     ; Must be set before starting Kermit.
DOBAUD  ENDP

; Get the current baud rate from the serial card and set it
; in the portinfo structure for the current port.  Returns normally.
; This is used during initialization.

GETBAUD PROC    NEAR
        ret                     ; Can't do this.
GETBAUD ENDP

; Use for DOS 2.0 and above.  Check the port status.  If no data, skip
; return.  Else, read in a char and return.
; Note added by [jrd]: The test for char-at-input-port is int 21h function
; 44h (ioctl) sub function 6 (get input status). On many systems an FFH will
; be reported (meaning Ready) even though no char is available; the Ready
; indication is misleading. In such cases the system will wait for a char
; and will appear to be hung. A preferrable method is to use the ROM Bios
; call int 14H function 3 (get port status) and if the lsb of the returned
; 8 bits in AH is 1 then a char is availble at the port; this assumes that
; the machine emulates this ROM Bios operation.
; Lastly, if the current code is used and the system hangs then reboot
; and say  ECHO Hello >COM1  before running Kermit; this should make MSDOS
; truely aware of the port's actual status. Dark grey magic. Good luck! [jrd]
PRTCHR  PROC    NEAR
        push bx
        push cx
        push si
        push bp
        cmp prthnd,0            ; Got a handle yet? [27d]
        jne prtch0              ; Yup just go on. [27d]
        call opnprt             ; Else 'open' the port. [27d]
prtch0: call chkxon
        mov bx,prthnd
        mov al,instat
        mov ah,ioctl            ; see note above [jrd]
        int dos
        or al,al
        jz prtch4               ; not ready...
        mov bx,prthnd
        mov ah,rddev
        mov cx,1
        mov dx,offset temp
        int dos
        cmp al,5                ; Error condition.
        je prt3x
        cmp al,6                ; Error condition
        je prt3x
        mov al,byte ptr temp
        mov bp,portval
        cmp ds:[bp].parflg,PARNON       ; no parity?
        je prtch3               ; then don't strip
        and al,7fh              ; else turn off parity
prtch3: pop bp
        pop si
        pop cx
        pop bx
        ret
prt3x:  mov ah,prstr
        mov dx,offset erms50
        int dos
prtch4: pop bp
        pop si
        pop cx
        pop bx
        jmp rskp                ; no chars...
PRTCHR  ENDP

; Local routine to see if we have to transmit an xon
chkxon  proc    near
        push    bx
        mov     bx,portval
        cmp     [bx].floflg,0   ; doing flow control?
        je      chkxo1          ; no, skip all this
        cmp     xofsnt,false    ; have we sent an xoff?
        je      chkxo1          ; no, forget it
        mov     ax,[bx].flowc   ; ah gets xon
        call    outchr          ; send it
        nop
        nop
        nop                     ; in case it skips
        mov     xofsnt,false    ; remember we've sent the xon.
chkxo1: pop     bx              ; restore register
        ret                     ; and return
chkxon  endp

; Send a break out the current serial port.  Returns normally.
SENDBR  PROC    NEAR
        ret
SENDBR  ENDP

; Position the cursor according to contents of DX:
; DH contains row, DL contains column.  Returns normally.
POSCUR  PROC    NEAR
        ret
POSCUR  ENDP

; Delete a character from the terminal.  This works by printing
; backspaces and spaces.  Returns normally.

DODEL   PROC    NEAR
        mov ah,prstr
        mov dx,offset delstr    ; Erase weird character.
        int dos
        ret
DODEL   ENDP

; Move the cursor to the left margin, then clear to end of line.
; Returns normally.

CTLU    PROC    NEAR
        mov ah,prstr
        mov dx,offset clrlin
        int dos
        call clearl
        ret
CTLU    ENDP

; Set the current port.

COMS    PROC    NEAR
        mov dx,offset comptab
        mov bx,0
        mov ah,cmkey
        call comnd
         jmp r
        push bx
        mov ah,cmcfm
        call comnd              ; Get a confirm.
         jmp comx               ;  Didn't get a confirm.
         nop
        pop bx
        cmp bl,2                ; Do they want to set device name? [27d]
        je coms2                ; Yes go get name. [27d]
        jg coms3                ; Else pick up file handle. [27d]
        mov flags.comflg,bl     ; Set the comm port flag.
        cmp flags.comflg,1      ; Using Com 1?
        jne coms0               ; Nope.
        mov ax,offset port1
        mov portval,ax
        ret
coms0:  mov ax,offset port2
        mov portval,ax
        ret
comx:   pop bx
        ret
coms2:  mov dx,offset dev1      ; Let user supply device name.
        call prompt
        mov ah,cmtxt
        mov bx,offset prtstr    ; Put name here
        mov dx,offset devhlp
        call comnd
         jmp coms21             ; Did user type ^C.
         nop
        mov al,0                ; Need a null
        mov [bx],al             ; To terminate string
        mov dx,offset prtstr    ; Point to string
        mov ah,open             ; Open port
        mov al,2                ; For reading and writing
        int dos
        jnc coms22              ; Success
coms21: mov ah,prstr
        mov dx,offset erms41
        int dos
        mov dx,offset deverr
        int dos
        ret
coms22: mov prthnd,ax           ; Save handle.
        ret
coms3:  mov dx,offset hnd2      ; Let user supply file handle.
        call prompt
        mov ah,cmtxt
        mov bx,offset rdbuf     ; Where to put input.
        mov dx,offset hndhlp    ; In case user wants help.
        call comnd
         jmp coms31             ; No go.
         nop
        cmp ah,4                ; Right amount of data?
        ja coms31               ; Too many chars.
        mov si,offset rdbuf
        call atoi               ; Convert to real number
         jmp coms31             ; Keep trying.
         nop
        mov prthnd,ax           ; Value returned in AX
        ret
coms31: mov ah,prstr            ; Else, issue a warning.
        mov dx,offset hnderr
        int dos
        ret                     ; Yes, fail.
COMS    ENDP

; Set heath emulation on/off.

VTS     PROC    NEAR
        jmp notimp
VTS     ENDP

VTSTAT  PROC    NEAR    ; For Status display [jrd]
        ret             ; no emulator status to display
VTSTAT  ENDP

notimp: mov ah,prstr
        mov dx,offset noimp
        int dos
        jmp prserr

; Initialize variables to values used by the generic MS DOS version.

lclini: mov flags.vtflg,0       ; Don't to terminal emulation.
        mov prthnd,0            ; No handle yet. [27d]
;       call opnprt             ; Get file handle for comm port.
        ret

; Get a file handle for the communications port.  Use DOS call to get the
; next available handle.  If it fails, ask user what value to use (there
; should be a predefined handle for the port, generally 3).  The open
; will fail if the system uses names other than "COM1" or "COM2".
opnprt: mov al,flags.comflg
        mov ah,0
        mov si,ax
        shl si,1                ; double index
        mov dx,prttab[si]
        mov ah,open
        mov al,2
        int dos
        jnc opnpr2
        mov ah,prstr            ; It didn't like the string.
        mov dx,offset erms41
        int dos
        mov dx,offset hnd1
        int dos
opnpr0: mov dx,offset hnd2      ; Ask user to supply the handle.
        call prompt
        mov ah,cmtxt
        mov bx,offset rdbuf     ; Where to put input.
        mov dx,offset hndhlp    ; In case user wants help.
        call comnd
         jmp opnpr3             ; Maybe user typed a ^C.
         nop
        mov si,offset rdbuf
        call atoi               ; Convert to real number
         jmp opnpr0             ; Keep trying.
         nop
        mov prthnd,ax           ; Value returned in AX
        ret
opnpr2: mov prthnd,ax           ; Call succeeded.
        ret
opnpr3: cmp flags.cxzflg,'C'    ; Did user type a ^C?
        jne opnpr4              ; No, don't say anything.
        mov ah,prstr            ; Else, issue a warning.
        mov dx,offset hnderr
        int dos
opnpr4: ret                     ; Yes, fail.

showkey:
        mov ax,offset shkmsg
        mov cx,shklen
        ret

; Initialization for using serial port.  Returns normally.
SERINI  PROC    NEAR
        cld                     ; Do increments in string operations
        call clrbuf             ; Clear input buffer.
        ret                     ; We're done.
SERINI  ENDP

; Reset the serial port.  This is the opposite of serini.  Calling
; this twice without intervening calls to serini should be harmless.
; Returns normally.

SERRST  PROC    NEAR
        ret                     ; All done.
SERRST  ENDP

; Produce a short beep.  The PC DOS bell is long enough to cause a loss
; of data at the port.  Returns normally.

BEEP    PROC    NEAR
        mov dl,bell
        mov ah,dconio
        int dos
        ret
BEEP    ENDP

; Dumb terminal emulator.  Doesn't work too well above 1200 baud (and
; even at 1200 baud you sometimes lose the first one or two characters
; on a line).
term    proc    near
        mov si,ax               ; this is source
        mov di,offset ourarg    ; place to store arguments
        mov ax,ds
        mov es,ax               ; address destination segment
        mov cx,size termarg
        rep movsb               ; copy into our arg blk
term1:  call prtchr
        jmp short term2         ; have a char...
        nop
        nop
        jmp short term3         ; no char, go on
term2:  push ax
        and al,7fh              ; mask off parity for terminal
        mov dl,al
        mov ah,conout
        int dos                 ; go print it
        pop ax
        test ourarg.flgs,capt   ; capturing output?
        jz term3                ; no, forget it
        call ourarg.captr       ; else call the routine
term3:  mov ah,dconio
        mov dl,0ffh
        int dos
        jz term1                ; no character, go on
        cmp al,ourarg.escc      ; escape char?
        je term4                ; yes, exit
        push ax                 ; save char
        mov ah,al
        or ah,80H               ; turn on hi bit so DOS doesn't interfere
        call outchr             ; output the character
        nop
        nop
        nop
        pop ax
        test ourarg.flgs,lclecho ; echoing?
        jz term1                ; no, continue loop
        mov dl,al
        mov ah,dconio
        int dos
        jmp term1               ; else echo and keep going
term4:  ret
term    endp

; Jumping to this location is like retskp.  It assumes the instruction
;   after the call is a jmp addr.

RSKP    PROC    NEAR
        pop bp
        add bp,3
        push bp
        ret
RSKP    ENDP

; Jumping here is the same as a ret.

R       PROC    NEAR
        ret
R       ENDP

code    ends
        end
