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MSSCOM.ASM
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Assembly Source File
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1988-02-12
|
59KB
|
1,242 lines
NAME msscom
; File MSSCOM.ASM
; Edit history:
; Last edit 1 Jan 1988
; 1 Jan 1988 version 2.30
; 30 Dec 1987 Do 5 retries, 10 ms apart, on sending bytes before failing.[jrd]
; 5 Nov 1987 Permit extra EOLs preceeding handshake char. [jrd]
; 28 Oct 1987 Replace CRC routine (CRCCLC). Delete CRCTAB and CRCTAB2 [ebb]
; 25 Oct 1987 Allow extra bytes between EOL and handshake char. [jrd]
; 31 July 1987 Correct timeofday routine, from Jack Bryans. Add 8-bit display
; 24 July 1987 Rewrite Debugging and rpack to log bytes received before
; the SOH char and to add occassional console read during receive. [jrd]
; 22 July 1987 Rewrite time of day material for no ambiguities. [jrd]
; 2 July 1987 Allow reception of junk chars between block check and
; end of line without generating an error condition. [jrd]
; 20 May 1987 Reject incoming null characters. [jrd]
; 16 May 1987 Make Port3 and Port4 data structures available. [jrd]
; 24 April 1987 Add error return in spack if output of char fails. [jrd]
; 5 April 1987 Add call to chkcon at end of spack to update flags quicker,
; suggested by Jack Bryans. [jrd]
; 24 March 1987 Modify debug display to sense debug separate from logging.[jrd]
; 21 March 1987 Change procedure Sleep to a) remove saveac macro and b) do
; a check of console for a c/r or a Control C to force a timeout. [jrd]
; 12 March 1987 make premature reception of EOL char a full error.
; Add clearing of serial port buffer before sending packets. [jrd]
; 28 Feb 1987 Add number of bytes sent and received for statistics. [jrd]
; 19 Feb 1987 Correct Sleep routine to avoid endless loop if ending time
; just exceeds midnight. [jrd]
; 1 Oct 1986 Version 2.29a
; 12 Sept 1986 bug fixes plus lenient search (ignore errors) for handshake
; character when receiving.
; 11 August 1986 Complete rewrite for overlapping computation with i/o,
; add Long Packet support. [jrd]
; 15 May 86 - Fix stack corruption problem in outpkt when padding chars
; used. Thanks to Bernie Eiben. [jrd]
; [2.29] code frozen on 6 May 1986 [jrd]
public data, spack, rpack, portval, port1, port2, port3, port4, hierr
public prtbase, nports, sleep, spause
include mssdef.h
biostod equ 1ah ; Bios time of day tic routine
stat_suc equ 0 ; success
stat_tmo equ 1 ; timeout
stat_chk equ 2 ; checksum mismatch
stat_ptl equ 4 ; packet too long
stat_int equ 8 ; user interrupt
stat_eol equ 10h ; eol char seen
datas segment public 'datas'
extrn flags:byte, trans:byte, pack:byte, fsta:word, fmtdsp:byte
prtbase label byte
port1 prtinfo <0FFFH,0,defpar,1,0,defhand,floxon>
port2 prtinfo <0FFFH,0,defpar,1,0,defhand,floxon>
port3 prtinfo <0FFFH,0,defpar,1,0,defhand,floxon>
port4 prtinfo <0FFFH,0,defpar,1,0,defhand,floxon>
rept portmax-4
prtinfo <0FFFH,0,defpar,1,0,defhand,floxon>
endm
;; systems with two ports can set portval to port1 or port2.
;; systems with more than two ports can set nports higher,
;; then set portval to the address prtbase+(#-1)*size prtinfo
;; where # is the desired port.
portval dw port1 ; Default is to use port 1.
nports db 2 ; # of known ports
hierr db 0 ; Non-ascii char (non-zero if yes).
parmsk db 0ffh ; parity mask (0FFH for 8bit data path) [umd]
spmes db 'Spack: $'
rpmes db 'Rpack: $'
crlf db cr,lf,'$'
cemsg db 'User intervention$'
sixzero dw 60 ; for div operation in rec packet timeouts
ninefive dw 95 ; for mult/div with long packets
temp dw ?
tmp db ?
linecnt dw ? ; debug line width counter
spause db 0 ; # millisec to wait before sending pkt
prvtyp db ? ; Type of last packet sent
pktptr dw ? ; Position in receive packet.
chksum dw ? ; running checksum (two char)
chrcnt dw ? ; number of bytes in data field of a packet
status dw ? ; status of packet receiver (0 = ok)
pktype db ? ; received packet TYPE holding area
debflg db ? ; debug display, send/receive flag
tmpflg db ? ; flags.cxzflg at entry to rpack
timeit db ? ; arm timeout counter
fairflg dw 0 ; fairness flag, for console/port reads.
time dw 2 dup (?) ; Sleep, when we should timeout.
rptim db 4 dup (?) ; read packet timeout slots
spkcnt dw ? ; number of bytes sent in this packet
rpkcnt dw ? ; number of bytes received in this packet
; Prolog, Data, Trailer must be kept together
prolog db 8 dup (?) ; Packet header (SOH, LEN, SEQ, TYPE, xlen)
data db maxpack+10 dup (?) ; Data field of packet (used in many places)
; checksum, eol, handshake + null term
datas ends
code segment public 'code'
extrn prtchr:near, clrbuf:near, outchr:near
extrn sppos:near, stpos:near, biterr:near, intmsg:near
extrn clearl:near, rppos:near, errpack:near, prtscr:near
extrn cptchr:near, strlen:near, pcwait:near
assume cs:code, ds:datas
; Packet routines
; Send_Packet
; This routine assembles a packet from the arguments given and sends it
; to the host.
;
; Expects the following:
; AH - Type of packet (D,Y,N,S,I,R,E,F,Z,T)
; ARGBLK - Packet sequence number
; ARGBK1 - Number of data characters
; Returns: +1 always
; Packet construction areas:
; Prolog (8 bytes) Data null Data
;+----------------------------------------+---------------+---------------+
;| SOH,LEN,SEQ,TYPE,Xlen(2-3),Xlen chksum | packet's data | chksum,EOL,HS |
;+----------------------------------------+---------------+---------------+
; where Xlen is 2 byte (Long) or 3 byte (Extra Long) count of bytes to follow.
;
SPKT PROC NEAR
spack: push ax ; save packet type (in ah)
call clrbuf ; clear serial port input buffer
call prtchr ; exercise receiver
nop
nop
nop
call clrbuf ; clear serial port input buffer
mov spkcnt,0 ; number of bytes sent in this packet
add fsta.pspkt,1 ; statistics, count a packet being sent
adc fsta.pspkt+2,0 ; ripple carry
mov al,spause ; Wait spause milliseconds before
xor ah,ah ; sending a packet
or al,al ; zero?
jz spk1 ; z = yes
call pcwait ; to let other side get ready
spk1: mov dh,trans.spad ; Get the number of padding chars.
spk2: dec dh
cmp dh,0
jl spk5 ; If none left proceed.
mov ah,trans.spadch ; Get the padding char.
push dx ; save loop counter
call outchr ; Output it.
jmp spk3 ; failed
nop ; must be three bytes
pop dx ; get loop counter
jmp spk2 ; do remaining padding chars
spk3: pop dx
pop ax
ret ; failed
pop dx
spk5: pop ax ; recover ah
mov prvtyp,ah ; Remember packet type
mov bx,portval ; Get current port structure [umd]
mov parmsk,0ffh ; Set parity mask for 8 bits [umd]
cmp [bx].parflg,parnon ; Using parity? [umd]
je spacka ; e = no. use mask as is. [umd]
mov parmsk,7fh ; else set mask for 7 data bits. [umd]
spacka: call snddeb ; do debug display (while it's still our turn)
mov pktptr,offset prolog
mov word ptr prolog,0
mov word ptr prolog+2,0
mov word ptr prolog+4,0
mov word ptr prolog+6,0
mov al,trans.ssoh ; Get the start of header char.
mov prolog,al ; Put SOH in the packet.
mov ax,pack.argblk ; SEQ
add al,20h ; ascii bias
mov prolog+2,al ; store SEQ in packet
mov ah,0
mov chksum,ax ; start checksum
mov al,prvtyp ; TYPE
mov prolog+3,al ; store TYPE
add chksum,ax ; add to checksum
;
; packet length type is directly governed here by length of header plus data
; field, pack.argbk1, plus chksum: regular <= 94, long <= 9024, else X long.
;
mov ax,pack.argbk1 ; DATA length
add ax,2 ; add SEQ, TYPE lengths
add al,trans.chklen ; add checksum length at the end
adc ah,0 ; propagate carry, yields overall new length
cmp ax,maxpack ; too big?
jle spdlp0 ; le = ok
ret ; return bad
spdlp0:
mov pack.argbk3,3 ; assume regular packet
cmp ax,94 ; longer than a regular?
ja spdlp1 ; a = use long
add al,20h ; convert length to ascii
mov prolog+1,al ; store LEN
mov ah,0
add chksum,ax ; add LEN to checksum
jmp spklp5 ; do regular
spdlp1: push ax ; Use Long packets (type 3)
push bx
push cx
push dx
sub ax,2 ; deduct SEQ and TYPE from above = data+chksum
mov pack.argbk3,0 ; assume type 0 packet
cmp ax,(95*95-1) ; longest type 0 packet (9024)
jbe spdlp3 ; be = type 0
mov pack.argbk3,1 ; type 1 packet
spdlp3: mov bx,pack.argbk3 ; add new LEN field to checksum
add bl,20h ; ascii bias, tochar()
mov bh,0
add chksum,bx ; add to running checksum
mov prolog+1,bl ; put LEN into packet
mov bx,offset prolog+4 ; address of extended length field
mov cx,1 ; a counter
xor dx,dx ; high order numerator of length
spdlp7: div ninefive ; divide ax by 95. quo = ax, rem = dx
push dx ; push remainder
inc cx ; count push depth
cmp ax,95 ; quotient >= 95?
jae spdlp7 ; ae = yes, recurse
push ax ; push for pop below
spdlp8: pop ax ; get a digit
add al,20h ; apply tochar()
mov [bx],al ; store in data field
add chksum,ax ; accumulate checksum for header
inc bx ; point to next data field byte
mov byte ptr[bx],0 ; insert terminator
loop spdlp8 ; get the rest
;
mov ax,chksum ; current checksum
shl ax,1 ; put two highest bits of al into ah
shl ax,1
and ah,3 ; want just those two bits
shr al,1 ; put al back in place
shr al,1
add al,ah ; add two high bits to earlier checksum
and al,03fh ; chop to lower 6 bits (mod 64)
add al,20h ; apply tochar()
mov [bx],al ; store that in length's header checksum
mov ah,0
add chksum,ax ; add that byte to running checksum
pop dx
pop cx
pop bx
pop ax
spklp5: push si ; assume soh, len, seq, type, extra len are in prolog
push di
push cx
push ds
pop es ; set es to data segment for implied es:di
mov si,offset prolog ; source
mov di,offset data-1 ; end point of destination
mov pktptr,offset data ; start of packet ptr for debug
cmp pack.argbk3,0 ; long packets?
jne spklp6 ; ne = no
add si,6 ; long packets
mov cx,7 ; seven bytes soh,len,seq,type, xl1,xl2,xlchk
jmp spklp8
spklp6: cmp pack.argbk3,1 ; extra long packets?
jne spklp7 ; ne = no
mov cx,8 ; extra long packets
add si,7
jmp spklp8
spklp7: add si,3 ; regular packets, slide up by four bytes
mov cx,4 ; number of bytes to move
spklp8: jcxz spklp9 ; no movement needed
sub pktptr,cx ; pktprt=new offset of prolog section
std
rep movsb ; move the protocol header, cx times
cld
spklp9: pop cx
pop di
pop si
mov bx,pktptr ; place where protocol section starts
spklp10:mov ah,[bx] ; protocol part
inc bx
call spkout ; send byte to serial port
jnc spklp11 ; nc = good send
jmp spackq ; bad send
spklp11:cmp bx,offset data ; done all protocol parts yet?
jb spklp10 ; b = not yet
mov bx,offset data ; select from given data buffer
mov dx,pack.argbk1 ; Get the number of data bytes in packet.
spack2: dec dx ; Decrement the char count.
js spack3 ; sign = no, finish up.
mov al,byte ptr[bx] ; get a data char
inc bx ; point to next char [umd]
test al,80h ; eighth bit set?
jz spackb ; z = no
and al,parmsk ; apply parity mask, may clear 8th bit [umd]
cmp hierr,0 ; printed high bit error yet? [umd]
jne spackb ; ne = yes [umd]
push ax
push bx
push cx
push dx
call biterr
pop dx
pop cx
pop bx
pop ax
mov hierr,0FFH ; set err flag.
spackb: mov ah,0
add chksum,ax ; add the char to the checksum [umd]
and chksum,0fffh ; keep only low order 12 bits
mov ah,al ; put char in ah where spkout wants it
call spkout ; send it
jnc spack2 ; Go get more data chars
jmp spackq ; bad send
spack3: mov cx,chksum
cmp trans.chklen,2 ; What kind of checksum are we using?
je spackx ; e = 2 characters.
jg spacky ; g = 3 characters.
mov ah,cl ; 1 char: get the character total.
mov ch,cl ; Save here too (need 'cl' for shift).
and ah,0C0H ; Turn off all but the two high order bits.
mov cl,6
shr ah,cl ; Shift them into the low order position.
mov cl,ch
add ah,cl ; Add it to the old bits.
and ah,3FH ; Turn off the two high order bits. (MOD 64)
add ah,' ' ; Add a space so the number is printable.
mov [bx],ah ; Put in the packet.
inc bx ; Point to next char.
call spkout ; send it
jnc spackz ; Add EOL char.
jmp spackq ; bad send
spacky: mov byte ptr[bx],0 ; null, to determine end of buffer.
push bx ; Don't lose our place.
mov bx,pktptr ; First checksummed character.
inc bx ; skip SOH
call crcclc ; Calculate the CRC.
pop bx
push cx ; save the crc
mov ax,cx ; Manipulate it here.
and ax,0F000H ; Get 4 highest bits.
mov cl,4
shr ah,cl ; Shift them over 4 bits.
add ah,' ' ; Make printable.
mov [bx],ah ; Add to buffer.
inc bx
pop cx ; Get back checksum value.
call spkout ; send it
jnc spackx
jmp spackq ; bad send
spackx: push cx ; Save it for now.
and cx,0FC0H ; Get bits 6-11.
mov ax,cx
mov cl,6
shr ax,cl ; Shift them bits over.
add al,' ' ; Make printable.
mov [bx],al ; Add to buffer.
inc bx
mov ah,al
call spkout ; send it
pop cx ; Get back the original.
jc spackq ; c = bad send
and cx,003FH ; Get bits 0-5.
add cl,' ' ; Make printable.
mov [bx],cl ; Add to buffer.
inc bx
mov ah,cl
call spkout ; send it
jnc spackz
spackq: RET ; bad send, do ret to caller of spack
spackz: mov ah,trans.seol ; Get the EOL the other host wants.
mov [bx],ah ; Put eol
inc bx
call deblin ; do debug display (while it's still our turn)
cmp flags.debug,0 ; In debug mode?
jne spackz0 ; ne = yes
test flags.capflg,logpkt ; log packets?
jz spackz1 ; z = no
spackz0:cmp linecnt,0 ; anything on current line?
je spackz1 ; e = no
mov dx,offset crlf ; finish line with cr/lf
call captdol ; to log file
spackz1:mov ah,trans.seol ; recover EOL
call spkout ; send it
jnc spackz2
jmp spackq ; bad send
spackz2:
mov ax,spkcnt ; number of bytes sent in this packet
add fsta.psbyte,ax ; total bytes sent
adc fsta.psbyte+2,0 ; propagate carry to high word
call chkcon ; check console for user interrupts
nop ; no action on plain rets
nop
nop
jmp rskp ; return successfully
SPKT ENDP
spkout: push ax ; send char in ah out the serial port
push bx ; return carry clear if success
push cx
push dx
mov tmp,1 ; retry counter
spkour: call outchr ; serial port transmitter procedure
jmp short spkoux ; bad send, retry
nop
inc spkcnt ; count number of bytes sent in this packet
pop dx
pop cx
pop bx
pop ax
clc ; carry clear for good send
ret
spkoux: cmp tmp,5 ; done 5 attempts on this char?
jge spkoux1 ; ge = yes, fail the sending
inc tmp
push ax
mov ax,10 ; wait 10 milliseconds
call pcwait
pop ax
jmp short spkour ; retry
spkoux1:pop dx ; failed to send char
pop cx
pop bx
pop ax
stc ; set carry for bad send
ret
; Calculate the CRC of the null-terminated string whose
; address is in BX. Returns the CRC in CX. Destroys BX and AX.
; The CRC is based on the SDLC polynomial: x**16 + x**12 + x**4 + 1.
; By Edgar Butt 28 Oct 1987 [ebb].
crcclc: push dx
mov dx,0 ; Initial CRC value is 0.
mov cl,4 ; Load shift count.
crc0: mov ah,[bx] ; Get the next char of the string.
cmp ah,0 ; If null, then we're done.
je crc1
inc bx
xor dl,ah ; XOR input with lo order byte of CRC.
mov ah,dl ; Copy it.
shl ah,cl ; Shift copy.
xor ah,dl ; XOR to get quotient byte in ah.
mov dl,dh ; High byte of CRC becomes low byte.
mov dh,ah ; Initialize high byte with quotient.
mov al,0
shr ax,cl ; Shift quotient byte.
xor dl,ah ; XOR (part of) it with CRC.
shr ax,1 ; Shift it again.
xor dx,ax ; XOR it again to finish up.
jmp short crc0
crc1: mov cx,dx ; Return it in CX.
pop dx
ret
; Receive_Packet
; This routine waits for a packet arrive from the host. It reads
; chars until it finds a SOH.
; Packet construction areas:
; Prolog (8 bytes+2 nulls) null Data null Data null
;+----------------------------------------+---------------+---------------+
;| SOH,LEN,SEQ,TYPE,Xlen(2-3),Xlen chksum | packet's data | chksum,EOL,HS |
;+----------------------------------------+---------------+---------------+
; where Xlen is 2 byte (Long) or 3 byte (Extra Long) count of bytes to follow.
RPACK PROC NEAR
call rcvdeb ; setup debug banner, if needed.
mov fairflg,0 ; set fairness flag
mov pktptr,offset prolog ; where to place packet prolog material
mov bx,pktptr ; bx = debug buffer pointer for new data
mov rpkcnt,0 ; number of bytes received in this packet
mov ax,0 ; most recently read char, initialize it
push bx
mov bl,flags.cxzflg ; Remember original value
mov tmpflg,bl ; Store it here
mov parmsk,0ffh ; parity mask, assume 8 bit data
mov bx,portval
cmp [bx].parflg,parnon ; parity is none?
pop bx
je rpack0 ; e = none
mov parmsk,07fh ; else strip parity (8th) bit
rpack0: call deblin ; debug, show chars received thus far
mov word ptr prolog,0 ; clear prolog and data fields
mov word ptr prolog+2,0
mov word ptr prolog+4,0
mov word ptr prolog+6,0
mov word ptr data,0
mov pktptr,offset prolog ; where to place packet prolog material
mov bx,pktptr ; bx = debug buffer pointer for new data
mov status,stat_suc ; assume success
call inchr ; Get a character. SOH
jmp rpack0a ; failure (eol, timeout, user intervention)
nop
rpack0b:mov byte ptr[bx],al ; store char in buffer
inc bx
cmp al,trans.rsoh ; Is the char the start of header char?
jne rpack0 ; ne = no, go until it is.
jmp rpack1 ; got the SOH char from the port
rpack0a:jc rpack0b ; c = hit eol from prev packet, restart
jmp rpack6 ; timeout or user intervention
rpack1: mov pktptr,offset prolog ; if we got here from below
mov bx,pktptr ; debug pointer
mov byte ptr[bx],al ; store SOH in buffer
inc bx
mov status,stat_suc ; say success, in case rescanning for pkt.
call inchr ; Get a character. LEN
jmp rpack4 ; failure
nop
mov byte ptr[bx],al ; store LEN in buffer
inc bx
mov ah,0
cmp al,trans.rsoh ; Is the char the start of header char?
jne rpack1e ; ne = no
jmp rpack7 ; yes, start over
rpack1e:mov chksum,ax ; start the checksum
sub al,20h ; unchar() to binary
mov pack.argbk1,ax ; Save the data count (byte)
call inchr ; Get a character. SEQ
jmp rpack4 ; failure
nop
mov byte ptr[bx],al ; store SEQ in buffer
inc bx
cmp al,trans.rsoh ; Is the char the start of header char?
jz rpack1 ; nz = yes, then go start over.
mov ah,0
add chksum,ax
sub al,' ' ; Get the real packet number.
mov ah,0
mov pack.argblk,ax ; Save the packet number. SEQ
call inchr ; Get a character. TYPE
jmp rpack4 ; failure
mov byte ptr[bx],al ; store TYPE in buffer
inc bx
cmp al,trans.rsoh ; Is the char the start of header char?
jz rpack1 ; nz = yes, then go start over.
mov pktype,al ; Save the message type
mov ah,0
add chksum,ax ; Add it to the checksum.
push bx
mov bx,portval ; Point to current port structure
cmp [bx].ecoflg,0 ; Is the host echoing?
pop bx
jne rpak11 ; No, packets not echoed
cmp al,prvtyp ; Packet type same as last sent?
jne rpak11 ; ne = no
mov prvtyp,0 ; clear to respond to next packet
jmp rpack0 ; Yes, chuck echoed packet
rpak11: call getlen ; get complicated data length (reg, lp, elp)
; into pack.argbk1 and kind into pack.argbk3
; carry set if error
jnc rpack1d ; nc = long packet checksum is ok
or status,stat_chk ; say bad checksum
jmp rpack4 ; checksum failure
rpack1d:
; Start of change.
; Now determine block check type for this packet. Here we violate the layered
; nature of the protocol by inspecting the packet type in order to detect when
; the two sides get out of sync. Two heuristics allow us to resync here:
; a. I and S packets always has a type 1 checksum.
; b. A NAK never contains data, so its block check type is argblk1.
cmp prolog+3,'S' ; Is this an "S" packet?
jne rpk0 ; ne = no.
mov trans.chklen,1 ; S packets use one byte checksums
jmp rpk3
rpk0: cmp prolog+3,'I' ; I packets are like S packets
jne rpk1
mov trans.chklen,1 ; I packets use one byte checksums
jmp rpk3
rpk1: cmp prolog+3,'N' ; Is this a NAK?
jne rpk3 ; ne = no.
cmp pack.argbk1,1 ; NAK, get length of data + chklen
jb rpk1a ; b = impossible length
cmp pack.argbk1,3 ; longest NAK (3 char checksum)
jbe rpk2 ; be = possible
rpk1a: or status,stat_ptl ; status = bad length
jmp rpack4 ; ret on impossible length
rpk2: mov ax,pack.argbk1
mov trans.chklen,al ; remainder must be checksum type for NAK.
rpk3: mov ax,pack.argbk1 ; get length of data + chksum
sub al,trans.chklen ; minus checksum length, for all packets
sbb ah,0 ; propagate borrow
mov pack.argbk1,ax ; store apparent length of data field
; End of change.
; now, for long packets we start the real data (after the extended byte
; count 3 or 4 bytes) at offset data and thus the checksumming starts
; such packets a few bytes earlier. [jrd]
push si
push di
push cx
mov di,offset data-1
mov si,offset prolog
mov pktptr,offset data
cmp pack.argbk3,0 ; long packets?
jne rpk5 ; ne = no
mov cx,7 ; seven bytes mark...type, xl,xl,xlchk
add si,6
jmp rpk7
rpk5: cmp pack.argbk3,1 ; extra long packets?
jne rpk6 ; ne = no
mov cx,8 ; extra long packets, no movement
add si,7
jmp rpk7
rpk6: add si,3 ; regular packets, slide by four bytes
mov cx,4 ; number of bytes to move
rpk7: jcxz rpk8 ; no movement needed
sub pktptr,cx ; pktptr=new offset of prolog section
push es ; save es
push ds
pop es ; set es to datas segment
std ; move backward
rep movsb ; move the protocol header, cx times
pop es
cld ; reset direction flag to normal
rpk8: pop cx
pop di
pop si
mov dx,pack.argbk1 ; length of data field, excl LP header
mov chrcnt,dx
mov dx,trans.rlongp ; longest packet we can receive
sub dl,trans.chklen ; minus checksum length
sbb dh,0 ; propagate borrow
cmp pack.argbk3,3 ; Regular Packet?
jne rpk8a ; ne = no
sub dx,2 ; minus SEQ, TYPE for regular packets
rpk8a: cmp dx,pack.argbk1 ; is data field too long?
jae rpk8b ; ae = not too big
or status,stat_ptl ; failure status, packet too long
jmp rpack4 ; too big, quit now
rpk8b: mov bx,offset data ; Point to the data buffer.
; Get DATA field characters
rpack2: dec chrcnt ; # data chars
js rpack3 ; s = exhausted data, go get the checksum.
call inchr ; Get a character into al. DATA
jmp rpack4 ; control-c, timeout (out of data), eol
nop
mov byte ptr[bx],al ; Put the char into the packet.
inc bx ; Point to the next character.
cmp al,trans.rsoh ; Is the char the start of header char?
jnz rpak2b ; nz = no
jmp rpack7 ; yes, then go start over.
rpak2b: mov ah,0
add chksum,ax
and chksum,0fffh ; keep only lower 12 bits
jmp rpack2 ; Go get another.
rpack3: call inchr ; Get a character. Start Checksum bytes
jmp rpack4 ; failed
nop
mov byte ptr[bx],al ; place to store checksum, EOL, HS for debug
inc bx ; point at next slot
cmp al,trans.rsoh ; Is the char the start of header char?
jne rpk3x ; ne = no
jmp rpack7 ; yes, then go start over.
rpk3x: sub al,' ' ; Turn the char back into a number.
mov cx,chksum ; current checksum
cmp trans.chklen,2 ; What checksum length is in use.
je rpackx ; e = Two character checksum.
jg rpacky ; g = Three character CRC.
shl cx,1 ; put two highest digits of al into ah
shl cx,1
and ch,3 ; want just those two bits
shr cl,1 ; put al back in place
shr cl,1
add cl,ch ; add two high bits to earlier checksum
and cl,03fh ; chop to lower 6 bits (mod 64)
cmp cl,al ; computed vs received checksum byte (binary)
je rpk3xa ; e = equal, so finish up.
or status,stat_chk ; say checksum failure
rpk3xa: jmp rpack4
rpack7: call deblin ; dump debugging information so far
jmp rpack1 ; For the jump out of range.
rpacky: mov tmp,al ; Save value from packet here.
push bx ; Three character CRC.
mov cx,[bx-1] ; save checksum char and next
mov temp,cx
mov word ptr[bx-1],0 ; put null at end of Data field for crc
mov bx,pktptr ; Where data for CRC is.
inc bx ; skip SOH
call crcclc ; Calculate the CRC and put into CX.
pop bx
mov ax,temp
mov [bx-1],ax ; restore char pair from above
mov ah,ch ; cx = 16 bit binary CRC of rcv'd data
and ah,0f0h ; Manipulate it here.
shr ah,1
shr ah,1 ; Get 4 highest bits.
shr ah,1
shr ah,1 ; Shift them over 4 bits.
cmp ah,tmp ; Is what we got == what we calculated?
je rpky1 ; e = yes
or status,stat_chk ; checksum failure
rpky1: call inchr ; Get next character of checksum.
jmp rpack4 ; Failed.
nop
mov byte ptr[bx],al ; put into buffer for debug
inc bx
cmp al,trans.rsoh ; Restarting?
je rpack7 ; e = yes
sub al,' ' ; Get back real value.
rpackx: mov tmp,al ; Save here for now.
push cx ; Two character checksum.
and cx,0FC0H ; Get bits 6-11.
mov ax,cx
mov cl,6
shr ax,cl ; Shift them bits over.
pop cx ; Get back the original.
cmp al,tmp ; Are they equal?
je rpkx1 ; yes
or status,stat_chk ; checksum failure
rpkx1: call inchr ; Get last character of checksum.
jmp rpack4 ; Failed.
nop
mov byte ptr[bx],al ; put into buffer for debug
inc bx
cmp al,trans.rsoh ; Restarting?
je rpack7 ; e = yes
sub al,' ' ; Get back real value.
and cx,003FH ; Get bits 0-5.
cmp al,cl ; Do the last chars match?
je rpack4 ; e = yes
or status,stat_chk ; say checksum failure
rpack4: test status,stat_tmo ; timeout?
jnz rpack6 ; nz = yes
test status,stat_eol ; premature eol?
jnz rpack4c ; nz = yes, try handshake
call inchr ; get eol char (ok = ret with carry set)
jnc rpack6 ; nc = timeout or user intervention
nop
cmp bx,offset data+maxpack+7 ; filled debug buffer yet?
ja rpack4e ; a = yes
mov byte ptr[bx],al ; put into buffer for debug
inc bx
rpack4e:cmp al,trans.rsoh ; soh already?
jne rpack4a ; ne = no
jmp rpack7 ; yes
rpack4a:test status,stat_eol ; got expected eol character?
pushf
and status,not stat_eol ; desired eol is not an error,
popf ; lack of eol is
jnz rpack4c ; nz = yes (note bit clearing above)
jmp short rpack4 ; keep looking for eol
rpack4c:
push bx ; test for line turn char, if handshaking
mov bx,portval
mov ah,[bx].hands ; get desired handshake char
cmp [bx].hndflg,0 ; doing half duplex handshaking?
pop bx
je rpack6 ; e = no
mov tmp,ah ; keep it here
call inchr ; get handshake char
jnc rpack5 ; nc = timeout or user intervention
nop
and status,not stat_eol ; ignore unexpected eol status here.
cmp bx,offset data+maxpack+7 ; filled debug buffer yet?
ja rpack4f ; a = yes
mov byte ptr[bx],al ; put into buffer for debug
inc bx
rpack4f:cmp al,trans.rsoh ; soh already?
jne rpack4d ; ne = no
jmp rpack7 ; yes
rpack4d:cmp al,tmp ; compare received char with handshake
jne rpack4c ; ne = not handshake, try again til timeout
rpack5: and status,not stat_tmo ; ignore timeouts on handshake char
rpack6: call deblin ; do debug display
cmp flags.debug,0 ; In debug mode?
jne rpack6a ; ne = yes
test flags.capflg,logpkt ; log packets?
jz rpack6b ; z = no
rpack6a:cmp linecnt,0 ; anything on current line?
je rpack6b ; e = no
mov dx,offset crlf ; finish line with cr/lf
call captdol ; to log file
rpack6b:call chkcon ; check console for user interrupt
nop
nop
nop
test status,stat_tmo ; did a timeout get us here?
jz rpack6c ; z = no
mov pktype,'T' ; yes, say 'T' type packet (timeout)
rpack6c:mov bl,tmpflg ; flags before rpack began
cmp bl,flags.cxzflg ; did flags change?
je rpack6e ; e = no
cmp flags.cxzflg,'C'; did user type contol-C?
je rpack6d ; e = yes
cmp flags.cxzflg,'E'; protocol exit request?
jne rpack6e ; ne = no
mov bx,offset cemsg ; user intervention message for error packet
call errpack ; send error message
rpack6d:mov pack.state,'A' ; and move to abort state
call intmsg ; show interrupt msg for control-C-E
rpack6e:mov ax,rpkcnt ; number of bytes received in this packet
add fsta.prbyte,ax ; total received bytes
adc fsta.prbyte+2,0 ; propagate carry to high word
add fsta.prpkt,1 ; count received packet
adc fsta.prpkt+2,0 ; ripple carry
mov ah,pktype ; return packet type in ah
cmp status,stat_suc ; successful so far?
jne rpack6x ; ne = no
jmp rskp ; success exit
rpack6x:ret ; failure exit
RPACK ENDP
; Check Console (keyboard). Ret if "action" chars: cr for forced timeout,
; Control-E for force out Error packet, Control-C for quit work now.
; Return rskp on Control-X and Control-Z as these are acted upon by higher
; layers. Consume and ignore anything else.
chkcon: mov dl,0ffh
mov ah,dconio ; read console
int dos
jz chkco5 ; z = nothing there
cmp al,cr ; carriage return?
je chkco3 ; e = yes, simulate timeout
cmp al,'C'-40h ; Control-C?
je chkco1 ; e = yes
cmp al,'E'-40h ; Control-E?
je chkco1 ; e = yes
cmp al,'X'-40h ; Control-X?
je chkco4 ; e = yes
cmp al,'Z'-40h ; Control-Z?
je chkco4 ; record it, take no immmediate action here
cmp al,0 ; scan code being returned?
jne chkcon ; ne = no
mov ah,dconio ; read and discard second byte
mov dl,0ffh
int dos
jmp chkcon ; else unknown, read any more
chkco1: add al,40h ; Make Control-C-E printable.
mov flags.cxzflg,al ; Remember what we saw.
chkco2: or status,stat_int ; interrupted
ret ; act now
chkco3: or status,stat_tmo ; cr simulates timeout
ret ; act now
chkco4: add al,40h ; make control-X-Z printable
mov flags.cxzflg,al ; put into flags
jmp rskp ; do not act on them here
chkco5: cmp flags.cxzflg,'C'; control-C intercepted elsewhere?
je chkco2 ; e = yes
jmp rskp ; else say no immediate action needed
getlen proc near ; compute packet length for short & long types
; returns length in pack.argbk1 and length
; type (0, 1, 3) in pack.argbk3
; returns length of data + checksum
mov ax,pack.argbk1 ; LEN from packet's second byte
xor ah,ah ; clear unused high byte
cmp al,3 ; regular packet has 3 or larger here
jb getln0 ; b = long packet
sub pack.argbk1,2 ; minus SEQ and TYPE = DATA + CHKSUM
mov pack.argbk3,3 ; store assumed length type (3 = regular)
clc ; clear carry for success
ret
getln0: push cx ; counter for number of length bytes
mov pack.argbk3,0 ; store assumed length type 0 (long)
mov cx,2 ; two base-95 digits
cmp al,0 ; is this a type 0 (long packet)?
je getln5 ; e = yes, go find & check length data
getln1: mov pack.argbk3,1 ; store length type (1 = extra long)
mov cx,3 ; three base 95 digits
cmp al,1 ; is this a type 1 (extra long packet)?
je getln5 ; e = yes, go find & check length data
pop cx
stc ; set carry bit to say error (unkn len code)
ret
getln5: ; chk header chksum and recover binary length
push dx ; save working reg
xor ax,ax ; clear length accumulator, low part
mov pack.argbk1,ax ; clear final length too
getln7: xor dx,dx ; ditto, high part
mov ax,pack.argbk1 ; length to date
mul ninefive ; multiply accumulation (in ax) by 95
mov pack.argbk1,ax ; save results
push cx
call inchr ; read another serial port char into al
nop ; should do something here about failures
nop
nop
pop cx
mov ah,0
mov byte ptr[bx],al ; store in buffer
inc bx
add chksum,ax
sub al,20h ; subtract space, apply unchar()
add pack.argbk1,ax ; add to overall length count
loop getln7 ; cx preset earlier for type 0 or type 1
mov dx,chksum ; get running checksum
shl dx,1 ; get two high order bits into dh
shl dx,1
and dh,3 ; want just these two bits
shr dl,1 ; put low order part back
shr dl,1
add dl,dh ; add low order byte to two high order bits
and dl,03fh ; chop to lower 6 bits (mod 64)
add dl,20h ; apply tochar()
push dx
call inchr ; read another serial port char
nop
nop
nop
pop dx
mov ah,0
mov byte ptr[bx],al ; store in buf for debug
inc bx
add chksum,ax
cmp dl,al ; our vs their checksum, same?
pop dx ; unsave regs (preserves flags)
pop cx
je getln9 ; e = checksums match, success
or status,stat_chk ; checksum failure
stc ; else return carry set for error
ret
getln9: clc ; clear carry (say success)
ret
getlen endp
; Get char from serial port into al, with timeout and console check.
; Ret carry clear if timeout or console char, Ret carry set if EOL seen,
; Rskp on other port chars. Fairflg allows occassional reads from console
; before looking at serial port, to avoid latchups.
inchr: mov timeit,0 ; reset timeout flag (do each char separately)
push bx ; save a reg
cmp fairflg,maxpack ; look at console first every now and then
jbe inchr1 ; be = not console's turn yet
call chkcon ; check console
jmp inchr5 ; got cr or control-c/e input
nop
mov fairflg,0 ; reset fairness flag for next time
inchr1: call prtchr ; Is there a serial port character to read?
jmp inchr6 ; Got one (in al); else does rskp.
nop
call chkcon ; check console
jmp inchr5 ; got cr or control-c/e input
nop
inchr2: cmp flags.timflg,0 ; Are timeouts turned off?
je inchr1 ; e = yes, just check for more input.
cmp trans.stime,0 ; Doing time outs?
je inchr1 ; e = no, just go check for more input.
push cx ; save regs
push dx ; Stolen from Script code.
cmp timeit,0 ; have we gotten time of day for first fail?
jne inchr4 ; ne = yes, just compare times
mov ah,gettim ; get DOS time of day
int dos ; ch = hh, cl = mm, dh = ss, dl = 0.01 sec
xchg ch,cl ; get ordering of low byte = hours, etc
mov word ptr rptim,cx ; hours and minutes
xchg dh,dl
mov word ptr rptim+2,dx ; seconds and fraction
mov bl,trans.stime ; our desired timeout interval (seconds)
mov bh,0 ; one byte's worth
mov temp,bx ; work area
mov bx,2 ; start with seconds field
inchr3: mov ax,temp ; desired timeout interval, working copy
add al,rptim[bx] ; add current tod digit interval
adc ah,0
xor dx,dx ; clear high order part thereof
div sixzero ; compute number of minutes or hours
mov temp,ax ; quotient, for next time around
mov rptim[bx],dl ; put normalized remainder in timeout tod
dec bx ; look at next higher order time field
cmp bx,0 ; done all time fields?
jge inchr3 ; ge = no
cmp rptim[0],24 ; normalize hours
jl inchr3a ; l = not 24 hours or greater
sub rptim[0],24 ; discard part over 24 hours
inchr3a:mov timeit,1 ; say have tod of timeout
inchr4: mov ah,gettim ; compare present tod versus timeout tod
int dos ; get the time of day
sub ch,rptim ; hours difference, ch = (now - timeout)
je inchr4b ; e = same, check mmss.s
jl inchr4d ; l = we are early
cmp ch,12 ; hours difference, large or small?
jge inchr4d ; ge = we are early
jl inchr4c ; l = we are late, say timeout
inchr4b:cmp cl,rptim+1 ; minutes, hours match
jb inchr4d ; b = we are early
ja inchr4c ; a = we are late
cmp dh,rptim+2 ; seconds, hours and minutes match
jb inchr4d ; b = we are early
ja inchr4c ; a = we are late
cmp dl,rptim+3 ; hundredths of seconds, hhmmss match
jb inchr4d ; b = we are early
inchr4c:or status,stat_tmo ; say timeout
pop dx
pop cx
jmp inchr5 ; timeout exit
inchr4d:pop dx
pop cx
jmp inchr1 ; not timed out yet
inchr5: pop bx ; here with console char or timeout
clc ; clear carry bit
ret ; failure
inchr6: pop bx ; here with char in al from port
and al,parmsk ; apply 7/8 bit parity mask
or al,al ; null char?
jnz inchr6b ; nz = no
inchr6a:jmp inchr ; ignore the null, read another char
inchr6b:cmp al,del ; ascii del byte?
je inchr6a ; e = yes, ignore it too
inc rpkcnt ; count received byte
cmp al,trans.reol ; eol char we want?
je inchr7 ; e = yes, ret with carry set
jmp rskp ; char is in al
inchr7: or status,stat_eol ; set status appropriately
stc ; set carry to say eol seen
ret ; and return qualified failure
; sleep for the # of seconds in al
; Preserve all regs. Added console input forced timeout 21 March 1987 [jrd]
sleep proc near
push ax
push cx
push dx
push ax ; save argument
mov ah,gettim ; DOS tod (ch=hh, cl=mm, dh=ss, dl=.s)
int dos ; get current time
pop ax ; restore desired # of seconds
add dh,al ; add # of seconds
sleep1: cmp dh,60 ; too big for seconds?
jb sleep2 ; no, keep going
sub dh,60 ; yes, subtract a minute's overflow
inc cl ; and add one to minutes field
cmp cl,60 ; did minutes overflow?
jb sleep1 ; no, check seconds again
sub cl,60 ; else take away an hour's overflow
inc ch ; add it back in hours field
jmp sleep1 ; and keep checking
sleep2: mov time,cx ; store desired ending time, hh,mm
mov time+2,dx ; ss, .s
sleep3: call chkcon ; check console for user timeout override
jmp short sleep5 ; have override
nop ; three bytes for rskp
mov ah,gettim ; get time
int dos ; from dos
sub ch,byte ptr time+1 ; hours difference, ch = (now - timeout)
je sleep4 ; e = hours match, check mmss.s
jl sleep3 ; l = we are early
cmp ch,12 ; hours difference, large or small?
jge sleep3 ; ge = we are early
jl sleep5 ; l = we are late, exit now
sleep4: cmp cl,byte ptr time ; check minutes, hours match
jb sleep3 ; b = we are early
ja sleep5 ; a = over limit, time to exit
cmp dx,time+2 ; check seconds and fraction, hhmm match
jb sleep3 ; b = we are early
sleep5: pop dx
pop cx
pop ax
ret
sleep endp
; Packet Debug display routines
rcvdeb: cmp flags.debug,0 ; In debug mode?
jne rcvde1 ; ne = yes
test flags.capflg,logpkt ; log packets?
jnz rcvde1 ; e = yes
ret ; no
rcvde1: mov debflg,'R' ; say receiving
jmp deb1
snddeb: cmp flags.debug,0 ; In debug mode?
jne sndde1 ; ne = yes
test flags.capflg,logpkt ; log packets?
jnz sndde1 ; yes
ret ; no
sndde1: mov debflg,'S' ; say sending
deb1: push ax ; Debug. Packet display.
push bx
push cx ; save some regs.
push dx
push di
test flags.debug,logpkt ; is debug active (vs just logging)?
jz deb1d ; z = no, just logging
cmp fmtdsp,0 ; non-formatted display?
je deb1d ; e = yes, skip extra line clearing
cmp debflg,'R' ; receiving?
je deb1a ; e = yes
call sppos ; spack: cursor position
jmp deb1b
deb1a: call rppos ; rpack: cursor position
deb1b: call clearl ; clear the line
mov dx,offset crlf
mov ah,prstr ; display
int dos
call clearl ; clear debug line and line beneath
deb1e: cmp debflg,'R' ; receiving?
je deb1c ; e = yes
call sppos ; reposition cursor for spack:
jmp deb1d
deb1c: call rppos ; reposition cursor for rpack:
deb1d: mov dx,offset spmes ; spack: message
cmp debflg,'R'
jne deb2
mov dx,offset rpmes ; rpack: message
deb2: call captdol ; record dollar terminated string in Log file
mov linecnt,7 ; number of columns used so far
pop di
pop dx
pop cx
pop bx
pop ax
ret ; done
; Display/log packet chars processed so far.
; Displays chars from pktptr to bx, both are pointers.
; Enter with bx = offset of next new char. All registers preserved
deblin: cmp flags.debug,0 ; In debug mode?
jne debln0 ; ne = yes
test flags.capflg,logpkt ; log packets?
jnz debln0 ; nz = yes
ret ; else nothing to do
debln0: push cx
push dx
push di
mov di,pktptr ; starting place for debug analysis
mov cx,bx ; place for next new char
sub cx,di ; minus where we start = number chars to do
cmp cx,0
jle debln5 ; le = nothing to do
debln2: cmp di,offset data+maxpack+10 ; end of buffer data?
ja debln5 ; a = all done
push cx ; save loop counter
cmp linecnt,70
jb debln3 ; b = not yet, get next data char
mov dx,offset crlf ; break line with cr/lf
call captdol ; and in log file
mov linecnt,0 ; setup for next line
debln3: mov dl,byte ptr [di]; get char
test dl,80h ; high bit set?
jz debln3b ; z = no
push dx ; save char in dl
mov dl,7eh ; show tilde char for high bit set
call captchr ; record in Log file
inc linecnt ; count displayed column
cmp linecnt,70 ; exhausted line count yet?
jb debln3a ; b = not yet
mov dx,offset crlf ; break line with cr/lf
call captdol ; and in log file
mov linecnt,0 ; setup for next line
debln3a:pop dx
and dl,7fh ; get lower seven bits here
debln3b:cmp dl,' ' ; control char?
jae debln4 ; ae = no
add dl,40h ; uncontrollify the char
push dx ; save char in dl
mov dl,5eh ; show caret before control code
call captchr ; record in Log file
inc linecnt ; count displayed column
cmp linecnt,70 ; exhausted line count yet?
jb debln3c ; b = not yet
mov dx,offset crlf ; break line with cr/lf
call captdol ; and in log file
mov linecnt,0 ; setup for next line
debln3c:pop dx ; recover char in dl
debln4: call captchr ; record char in dl in the log file
inc di ; done with this char, point to next
inc linecnt ; one more column used on screen
pop cx ; recover loop counter
loop debln2 ; get next data char
debln5: pop di
pop dx
pop cx
ret
captdol proc near ; write dollar sign terminated string in dx
; to the capture file (Log file). [jrd]
push ax ; save regs
push si
mov si,dx ; point to start of string
captdo1:lodsb ; get a byte into al
cmp al,'$' ; at the end yet?
je captdo2 ; e = yes
mov dl,al
call captchr ; Log the char
jmp short captdo1 ; repeat until dollar sign is encountered
captdo2:pop si
pop ax
ret
captdol endp
captcx proc near ; record counted string, starts in di, count
; is in cx. [jrd]
jcxz captc2 ; if count = zero, exit now
push ax ; save regs
push cx
push si
mov si,di ; get start address
captc1: lodsb ; get a char into al
call cptchr ; record it, cptchr is in msster.asm
loop captc1 ; do this cx times
pop si
pop cx
pop ax
captc2: ret
captcx endp
captchr proc near ; record char in dl into the Log file
push ax
cmp flags.debug,0 ; debug display active?
jz captch1 ; z = no.
mov ah,conout
int dos ; display char in dl
captch1:test flags.capflg,logpkt ; logging active?
jz captch2 ; z = no
mov al,dl ; where cptchr wants it
call cptchr ; record the char, cptchr is in msster.asm
captch2:pop ax
ret
captchr 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
