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Assembly Source File | 1992-03-29 | 59KB | 1,462 lines

page 55,132 title "BBPLUS - Compuserve B+ Protocol Module" ; --------------------------------------------------------------------- ; ; Maintenance Log: ; ; Version Date Description Who ; ------- ------- ---------------------------------- ---------------- ; 1.0 08Feb91 Initial version complete Flanders/Holmes ; ; --------------------------------------------------------------------- protocol segment para public 'code' assume cs:protocol start: jmp bpmbplus ; jump to start db "BD" ; backdown protocol ID db 1 ; nbr of protocols db "B" ; invocation letter db "CIS B+ V1.0 ", 0 ; name to display db 1 ; protocol number ; -------------------------------------------------------------------- ; Macro(s) ; -------------------------------------------------------------------- FARRET macro ; far return macro db 0cbh endm NSTATE macro nxtstate ; go to next state ifnb <nxtstate> ; if next state given mov state, nxtstate ; move in next state endif stc ; tell state_exec to do it ret ; .. continue endm XSTATE macro nxtstate ; exit the state machine ifnb <nxtstate> ; if next state given mov state, nxtstate ; move in next state endif clc ; tell state_exec to do it ret ; .. continue endm ; --------------------------------------------------------------------- ; Protocol characters equates ; --------------------------------------------------------------------- $ETX = 03h ; Trailer byte $ENQ = 05h ; Enquiry code $CR = 0Dh ; Carriage return $DLE = 10h ; Lead in byte $NAK = 15h ; Negative acknowledgement ; --------------------------------------------------------------------- ; Local stack ; --------------------------------------------------------------------- even bpmstack db 32 dup ("St") ; local stack area bpmstackend db "Es" ; End of local stack stackoffset dw offset bpmstackend ; New stack pointer ; --------------------------------------------------------------------- ; State definitions ; --------------------------------------------------------------------- $ST_INIT = -1 ; Awaiting initialization $ST_DLE = 0 ; DLE seen $ST_DLEB = 2 ; <DLE>B seen $ST_GETDATA = 4 ; Getting data in packet $ST_GETCKS = 6 ; Getting checksum $ST_GETCRC = 8 ; Getting crc $ST_VERCRC = 10 ; Verifying CRC $ST_VERCKS = 12 ; Verifying Checksum $ST_VERPKT = 14 ; Verifying Packet $ST_SNDNAK = 16 ; Sending a NAK $ST_SNDACK = 18 ; Sending an ACK $ST_GETDLE = 20 ; Wait for a DLE state dw $ST_INIT ; current state state_jmp dw bpdle ; 0: DLE seen dw bpdleb ; 2: <DLE>B seen dw bpgetdata ; 4: Getting data in packet dw bpgetcks ; 6: Getting checksum dw bpgetcrc ; 8: Getting crc dw bpvercrc ; 10: Verifying CRC dw bpvercks ; 12: Verifying Checksum dw bpverpkt ; 14: Verifying Packet dw bpsndnak ; 16: Sending a NAK dw bpsndack ; 18: Sending an ACK dw bpgetdle ; 20: Wait for a DLE ; --------------------------------------------------------------------- ; Transport Parameter Packet ; ; This protocol supports the following: ; ; Send window: 1 packet Receive window: 2 packets ; Block size: 512 bytes Check method: CRC ; Transport Layer: No Download resume: No ; Upload Resume: No File information: No ; ; Data Quoting: <ETX> <ENQ> <DLE> <DC1> <DC3> and <NAK> ; --------------------------------------------------------------------- tp_seq db ? ; sequence number tp_msg db "+", 0, 1, 4, 1, 1, 0 ; Transport parmameter pkt tp_msgq db 14h, 0, 0d4h, 0 ; quoting level db $ETX tp_msg_len = $-tp_seq ; Length of message ; --------------------------------------------------------------------- ; Data areas ; --------------------------------------------------------------------- flgs db 0 ; various flags flgfnc = 10000000b ; 1... .... callback active flgrcv = 01000000b ; .1.. .... character rcv'd flgcan = 00100000b ; ..1. .... cancel req'd flgtmo = 00010000b ; ...1 .... timeout flgopen = 00001000b ; .... 1... file is open flgrec = 00000100b ; .... .1.. record available bparea label byte ; internal BPAREA bpflg db 0 ; BPLUS flags bpfcrc = 10000000b ; 1... .... Use CRC checking bpfqut = 01000000b ; .1.. .... Next is quoted char bpseq db '0' ; current sequence number bpq db 8 dup (0ffh) ; default quoting set ubp_area dd ? ; users' save area ubp_areao equ word ptr ubp_area ; offset ubp_areas equ word ptr ubp_area+2 ; segment bpqc00 db 32 dup (0) ; 00h-1fh quoting bpqc80 db 32 dup (0) ; 80h-9fh quoting ticks dw ? ; entry nbr ticks jmptab dw init ; 0: initialization call dw fncok ; 2: last function ok dw fncfail ; 4: last function failed dw commchar ; 6: character received dw kbdchar ; 8: keystroke encountered MAXCODE = 8 ; maximum entry code CHRTMOUT = ((10*182)/10) ; 10 second char timeout PKTTMOUT = ((25*182)/10) ; 25 second char timeout MAXERRS = 10 ; maximum errors in row errors db 0 ; error counter filename db 65 dup (0) ; space for filename packet db 520 dup (?) ; packet buffer rcvaddr dw offset packet ; address for next receive ckbyte2 db ? ; byte 2 of chk val (crc) ckbyte1 db ? ; byte 1 (crc or cksum) crcval equ word ptr ckbyte2 ; .. to access it as a word chksumval equ byte ptr ckbyte1 ; .. to access it as a byte oldds dw ? ; caller's ds oldsp dw ? ; caller's sp oldss dw ? ; caller's ss init2x db 13, 'B+: Init called 2x', 13, 0 badfnc db 13, 'B+: Bad fnc code', 13, 0 openerr db 13, 'B+: Unable to open requested file', 13, 0 timedout db 13, 'B+: Timeout, protocol ended', 13, 0 toomany db 13, 'B+: Too many errors', 13, 0 notinited db 13, "B+: Not init'd first", 13, 0 sendercan db 13, 'B+: Download cancelled', 13, 0 success db 13, 'B+: Download completed OK', 13, 0 writerr db 13, 'B+: Aborted: write error', 13, 0 openok db 13, 'B+: Receiving ', 0 alrdyopen db 13, 'B+: File opened twice', 13, 0 unknownpkt db 13, 'B+: Unknown packet type', 13, 0 noupload db 13, "B+: Can't upload", 13, 0 clsb4open db 13, 'B+: Close before open', 13, 0 staterr0 db 13, 'B+: Staterr 0', 13, 0 staterr1 db 13, 'B+: Staterr 1', 13, 0 panicmsg dw 7 db 10h, 10h, 10h, 10h, 10h, "++" ; --------------------------------------------------------------------- ; Protocol Mainline ; --------------------------------------------------------------------- bpmbplus proc ; entry point push es ; save caller's regs push ds mov cs:oldds, ds ; keep copy of caller's ds mov cs:oldss, ss ; save caller's stack mov cs:oldsp, sp mov cs:ticks, ax ; save entry ticks mov ax, cs ; ax -> our segment mov ds, ax ; ds -> our segment mov es, ax ; es -> our segment cli ; no interrupts .. mov ss, ax ; ss -> our segment mov sp, stackoffset ; sp -> end of stack sti ; .. allow ints again cmp di, MAXCODE ; q. is code ok? ja bpmbplus90 ; a. no .. return "done" test di, 1 ; q. is code even? jnz bpmbplus90 ; a. no .. return "done" jmp jmptab[di] ; .. call requested routine bpmbplus90: lea bx, badfnc ; bx -> bad function code jmp proto_err ; issue error and leave bpmbplus endp ; --------------------------------------------------------------------- ; Initialization call; ds:bx -> operands (filename) ; --------------------------------------------------------------------- init proc cmp state, $ST_INIT ; q. already init'd? je init00 ; a. no .. continue lea bx, init2x ; bx -> error message jmp proto_err ; .. kill the protocol init00: mov ubp_areao, si ; save user's offset push oldds ; push user's ds pop ubp_areas ; .. set bparea segment push ds ; save our ds lds si, ubp_area ; ds:si -> user's area lea di, bparea ; di -> our bp area mov cx, 10 ; cx = bytes to move cld ; .. in upward direction rep movsb ; .. move it in. pop ds ; restore our ds lea si, bpq ; si -> quote parameters lea di, bpqc00 ; di -> quote array call bd_setq ; setup quote array mov state, $ST_DLE ; set state to DLE SEEN mov bx, CHRTMOUT ; bx = ticks to wait call setimer ; .. set the timer jmp proto_ok ; .. return to caller init endp ; --------------------------------------------------------------------- ; Last function executed ok -or- simple dispatch ; flgfnc = 0: simple dispatch ; fncfnc = 1: state return ; -- Carry is cleared ; --------------------------------------------------------------------- fncok proc test flgs, flgfnc ; q. callback return? jz fncok05 ; a. no .. dispatch clc ; show function succeeded ret ; .. rtn to callback caller fncok05: cmp state, $ST_INIT ; q. init'd yet? jne fncok10 ; a. yes .. continue lea bx, notinited ; bx -> not init'd msg jmp proto_err ; .. kill the protocol fncok10: jmp short check_rec ; see if record received fncok endp ; --------------------------------------------------------------------- ; Previous function failed Carry set to show failure ; --------------------------------------------------------------------- fncfail proc ; last function failed test flgs, flgfnc ; q. callback return? jnz fncfail10 ; a. yes .. continue lea bx, staterr1 ; bx -> state error msg jmp proto_err ; .. tell user & die fncfail10: stc ; set carry to show fail ret ; return to callback caller fncfail endp ; --------------------------------------------------------------------- ; Process Communications Character dl = character ; --------------------------------------------------------------------- commchar proc cmp state, $ST_INIT ; q. init'd yet? jne commchar05 ; a. yes .. continue lea bx, notinited ; bx -> not init'd msg jmp proto_err ; .. kill the protocol commchar05: test flgs, flgfnc ; q. callback return? jz commchar10 ; a. no .. continue lea bx, staterr0 ; bx -> state error msg jmp proto_err ; .. tell user & die commchar10: mov bx, rcvaddr ; bx -> receive address mov [bx], dl ; save received character or flgs, flgrcv ; show a char was received jmp short check_rec ; see if record received commchar endp ; --------------------------------------------------------------------- ; Process keyboard character dl = character ; --------------------------------------------------------------------- kbdchar proc cmp state, $ST_INIT ; q. init'd yet? jne kbdchar05 ; a. yes .. continue lea bx, notinited ; bx -> not init'd msg jmp proto_err ; .. kill the protocol kbdchar05: test flgs, flgfnc ; q. callback return? jz kbdchar10 ; a. no .. continue lea bx, staterr0 ; bx -> state error msg jmp proto_err ; .. tell user & die kbdchar10: cmp dx, 4F00H ; q. END key? jnz kbdchar20 ; a. no .. skip it or flgs, flgcan ; show cancel requested. kbdchar20: jmp short check_rec ; see if record received kbdchar endp ; --------------------------------------------------------------------- ; See if record received ; --------------------------------------------------------------------- check_rec proc call state_exec ; exec the state machine test flgs, flgrec ; q. record received? jz chk_rec90 ; a. no .. exit and flgs, not flgrec ; shut off indicator cmp packet+1, '+' ; q. transport parms? jne chk_rec10 ; a. no .. check next call proc_tport ; process transport rec jmp proto_ok ; .. continue chk_rec10: cmp packet+1, 'T' ; q. transfer packet? jne chk_rec20 ; a. no .. check next call proc_trec ; process T record jmp proto_ok ; .. continue chk_rec20: cmp packet+1, 'N' ; q. data packet? jne chk_rec30 ; a. no .. check next call proc_nrec ; process N record jmp proto_ok ; .. continue chk_rec30: lea bx, sendercan ; else .. sender cancelled it cmp packet+1, 'F' ; q. failure packet? je chk_rec40 ; a. yes .. kill protocol lea bx, unknownpkt ; unknown packet type chk_rec40: call panic ; panic abort! jmp proto_err ; .. the the users chk_rec90: jmp proto_ok ; .. continue later check_rec endp ; --------------------------------------------------------------------- ; Process transport (+) record ; --------------------------------------------------------------------- proc_tport proc lea si, packet+8 ; point at quoting set lea di, bpq ; di -> quoting set mov cx, 4 ; words to move cld ; .. in upward direction rep movsw ; .. move in the quote set mov al, packet+5 ; al = tp's crc flag push ax ; .. save on stack mov al, packet ; get his packet # mov bpseq, al ; .. save it in ours call nxtseq ; set next sequence nbr mov al, bpseq ; al = next sequence no mov tp_seq, al ; .. save in seq record lea si, tp_seq ; si -> our tport record lea di, packet ; di -> send packet area mov cx, tp_msg_len ; cx = length o'packet call bd_setout ; .. set up output pop ax ; restore crc flag and bpflg, not bpfcrc ; assume checksum or al, al ; q. use CRC? jz tport10 ; a. no .. continue or bpflg, bpfcrc ; .. set on CRC tport10: mov bx, di ; bx -> string to send mov di, 18 ; di = send 2cnt string call callback ; .. send it out lea si, bpq ; si -> quote parameters lea di, bpqc00 ; di -> quote array call bd_setq ; setup new quote array and flgs, not flgtmo ; reset timout mov bx, PKTTMOUT ; .. use packet timout call setimer ; .. reset timer mov state, $ST_GETDLE ; .. set next state ret ; .. and return to caller proc_tport endp ; --------------------------------------------------------------------- ; Process T record ; --------------------------------------------------------------------- proc_trec proc cmp packet+2, 'D' ; q. send to us (download)? jne trec10 ; a. no .. check next lea bx, alrdyopen ; file already open test flgs, flgopen ; q. file open? jnz trec06 ; a. yes.. error lea si, packet+4 ; si -> file name lea di, filename ; di -> output area cld ; .. address ascending trec03: lodsb ; al = filename char cmp al, ' ' ; q. above blank? ja trec05 ; a. yes .. xor al, al ; else .. clear al trec05: stosb ; .. put char in filename or al, al ; q. end of filename? jnz trec03 ; a. no .. continue lea bx, filename ; bx -> filename to open mov di, 2 ; di = open a file call callback ; ask for open jnc trec07 ; .. continue protocol call panic ; kill the protocol lea bx, openerr ; bx -> open error msg trec06: jmp proto_err ; .. die now trec07: lea bx, openok ; bx -> opened ok mov di, 12 ; di = display ASCIIZ call callback ; .. display the message lea bx, filename ; bx -> filename opened mov di, 12 ; di = display ASCIIZ call callback ; .. display the message mov bl, $CR ; bx -> carriage return mov di, 14 ; di = display character call callback ; .. display the message call nxtseq ; set next sequence number call bpsndack ; .. ack the pack or flgs, flgopen ; .. show file open ret ; .. continue trec10: cmp packet+2, 'C' ; q. closing file? jne trec20 ; a. no .. check next call nxtseq ; get next sequence number call bpsndack ; send an ack lea bx, clsb4open ; close before open test flgs, flgopen ; q. file open? jz trec90 ; a. no .. error and flgs, not flgopen ; reset open flag lea bx, success ; bx -> success jmp proto_err ; .. return to caller trec20: lea bx, noupload ; bx -> no upload msg cmp packet+3, 'U' ; q. upload from us? je trec30 ; a. no .. uh oh. lea bx, unknownpkt ; bx -> unknown packet type trec30: call panic ; panic abort! trec90: jmp proto_err ; .. tell the user proc_trec endp ; --------------------------------------------------------------------- ; Process data packet ; --------------------------------------------------------------------- proc_nrec proc mov cx, rcvaddr ; cx = next rcv addr sub cx, offset packet ; cx = len of packet sub cx, 3 ; cx = len of data jz nrec10 ; .. skip if no data mov word ptr packet, cx ; .. save in packet lea bx, packet ; bx -> packet mov di, 4 ; di = write data call callback ; q. write that data ok? jc nrec20 ; a. yes .. continue nrec10: call nxtseq ; .. set for next sequence call bpsndack ; else .. send an ack ret ; .. let it keep running nrec20: call panic ; abort the protocol lea bx, writerr ; bx -> write error message jmp proto_err ; .. kill the protocol proc_nrec endp ; --------------------------------------------------------------------- ; Run the state machine ; --------------------------------------------------------------------- state_exec proc cmp ticks, 0 ; q. timeout on ticks? jg state10 ; a. no .. continue or flgs, flgtmo ; timeout occurred state10: mov bx, state ; bx = state offset call state_jmp[bx] ; .. go to appropriate state jc state10 ; .. next state ret ; return to caller state_exec endp ; --------------------------------------------------------------------- ; State: Wait for DLE ; --------------------------------------------------------------------- bpgetdle proc test flgs, flgcan ; q. user cancel? jz bpgdle00 ; a. no .. continue call panic ; panic abort and flgs, not flgcan ; .. and shut off flag bpgdle00: test flgs, flgrcv ; q. character received? jnz bpgdle10 ; a. yes .. check it out mov bx, PKTTMOUT ; bx = packet timeout call chktimer ; q. timeout? jz bpgdle05 ; a. no .. continue lea bx, timedout ; bx -> timeout message jmp chk_err ; see if too many errors bpgdle05: XSTATE ; .. exit the state machine bpgdle10: mov bx, rcvaddr ; bx -> received char mov al, [bx] ; al = received char and flgs, not flgrcv ; reset receive flag cmp al, $DLE ; q. <DLE> seen? je bpgdle50 ; a. yes .. process it cmp al, $ENQ ; q. <ENQ> seen? jne bpgdle15 ; a. no .. continue NSTATE $ST_SNDACK ; else .. send an ACK bpgdle15: cmp al, $NAK ; q. <NAK> received? jne bpgdle20 ; a. no .. continue and flgs, not flgtmo ; bx -> protocol error msg XSTATE ; .. stay in state bpgdle20: cmp al, $ETX ; q. ETX? jne bpgdle05 ; a. no .. continue NSTATE $ST_SNDNAK ; else .. send a NAK bpgdle50: mov bx, CHRTMOUT ; set character timout call setimer ; .. reset timer mov errors, 0 ; .. reset errors and flgs, not flgtmo ; .. reset timout XSTATE $ST_DLE ; .. state = DLE seen bpgetdle endp ; --------------------------------------------------------------------- ; State: DLE Seen ; --------------------------------------------------------------------- bpdle proc test flgs, flgrcv ; q. character received? jnz bpdle10 ; a. yes .. check it out mov bx, CHRTMOUT ; bx = character timeout call chktimer ; q. timeout? jz bpdle05 ; a. no .. continue lea bx, timedout ; bx -> timeout message jmp chk_err ; see if too many errors bpdle05: XSTATE ; exit the state machine bpdle10: mov bx, rcvaddr ; bx -> received char mov al, [bx] ; al = received char and flgs, not flgrcv ; .. shut off char rcvd cmp al, 'B' ; q. <DLE> B seen? je bpdle50 ; a. yes .. process it cmp al, '0' ; q. possible ack? jb bpdle12 ; a. no .. continue cmp al, '9' ; q. is it an ACK? ja bpdle12 ; a. no .. continue cmp al, bpseq ; q. it it THE ACK? jne bpdle15 ; a. no .. continue jmp short bpdle15 ; .. continue bpdle12: cmp al, $ENQ ; q. Enquiry? jne bpdle15 ; a. no .. continue NSTATE $ST_SNDACK ; .. resend an ack bpdle15: mov bx, PKTTMOUT ; bx = packet timout call setimer ; .. set the timer XSTATE $ST_GETDLE ; else .. get a DLE bpdle50: mov bx, CHRTMOUT ; bx = character timeout call setimer ; set timer to 10 sec mov errors, 0 ; reset errors and flgs, not flgtmo ; reset timout mov rcvaddr, offset packet ; address of sequence XSTATE $ST_DLEB ; set next state bpdle endp ; --------------------------------------------------------------------- ; State: <DLE> B seen ; --------------------------------------------------------------------- bpdleb proc test flgs, flgrcv ; q. character received? jnz bpdleb10 ; a. yes .. check it out mov bx, CHRTMOUT ; bx = character timeout call chktimer ; q. timeout? jz bpdleb90 ; a. no .. continue NSTATE $ST_SNDNAK ; send a NAK bpdleb10: mov bx, rcvaddr ; bx -> received char mov al, [bx] ; al = char received cmp al, $ENQ ; q. ENQ received? jne bpdleb20 ; a. no .. save character XSTATE $ST_SNDACK ; send an ACK bpdleb20: call charcvd ; receive the char and flgs, not flgtmo ; reset any timeout mov bx, CHRTMOUT ; .. set for char timeout call setimer ; .. reset the timer mov errors, 0 ; .. reset error counter XSTATE $ST_GETDATA ; .. state = get data bpdleb90: XSTATE ; .. continue bpdleb endp ; --------------------------------------------------------------------- ; State: Get data ; --------------------------------------------------------------------- bpgetdata proc test flgs, flgrcv ; q. character received? jnz bpgdat10 ; a. yes .. check it out mov bx, CHRTMOUT ; bx = character timeout call chktimer ; q. timeout? jz bpdleb90 ; a. no .. continue NSTATE $ST_SNDNAK ; send a NAK bpgdat10: mov bx, rcvaddr ; bx -> received char mov al, [bx] ; al = char received test bpflg, bpfqut ; q. awaiting quoted? jz bpgdat20 ; a. no .. continue cmp al, 60h ; q. upper set? pushf ; .. save results and al, 1fh ; set off upper bits popf ; q. add 80 hex? jb bpgdat15 ; a. no .. leave as is. add al, 80h ; else .. 80h-9fh bpgdat15: mov [bx], al ; save unquoted char and bpflg, not bpfqut ; .. shut off quoting jmp short bpgdat85 ; .. and continue protocol bpgdat20: cmp al, $DLE ; q. quoted char? jne bpgdat25 ; a. no .. continue and flgs, not flgrcv ; set off received flag or bpflg, bpfqut ; .. and set on quoted flag jmp short bpgdat90 ; .. and continue bpgdat25: cmp al, $ETX ; q. ETX received? jne bpgdat30 ; a. no .. check next call charcvd ; save the ETX mov state, $ST_GETCKS ; get first byte of check jmp short bpgdat90 ; .. continue processing bpgdat30: cmp al, $ENQ ; q. ENQ received? jne bpgdat85 ; a. no .. received char mov state, $ST_SNDACK ; .. send out an ack jmp short bpgdat90 ; .. and continue bpgdat85: call charcvd ; .. and process it bpgdat90: and flgs, not flgtmo ; reset timeout mov bx, CHRTMOUT ; .. set to CHAR timout call setimer ; .. reset the timer XSTATE ; .. and continue bpgetdata endp ; --------------------------------------------------------------------- ; Wait for checksum char ; --------------------------------------------------------------------- bpgetcks proc test flgs, flgrcv ; q. character received? jnz bpgcks10 ; a. yes .. check it out mov bx, CHRTMOUT ; bx = character timeout call chktimer ; q. timeout? jz bpgcks90 ; a. no .. continue XSTATE $ST_SNDNAK ; send a NAK bpgcks10: mov bx, rcvaddr ; bx -> received char mov al, [bx] ; al = char received test bpflg, bpfqut ; q. quoting active? jz bpgcks50 ; a. no .. check/save char and bpflg, not bpfqut ; .. reset quoting flag cmp al, 60h ; q. 80-9f range? pushf ; .. save the answer and al, 1fh ; .. upper bits off popf ; .. restore answer .. jb bpgcks70 ; a. no .. store as is add al, 80h ; else.. reconstitute 80-9f jmp short bpgcks70 ; .. and save it bpgcks50: cmp al, $DLE ; q. quoted char? jne bpgcks70 ; a. no .. continue and flgs, not flgrcv ; "receive" the quote or bpflg, bpfqut ; show quoted char expected XSTATE ; .. and say in state bpgcks70: and flgs, not flgrcv ; show byte processed mov ckbyte1, al ; save as checksum mov state, $ST_GETCRC ; .. assume CRC checking test bpflg, bpfcrc ; q. using CRC? jnz bpgcks90 ; a. yes .. continue NSTATE $ST_VERCKS ; else .. verify checksum bpgcks90: XSTATE ; .. continue bpgetcks endp ; --------------------------------------------------------------------- ; Wait for CRC character ; --------------------------------------------------------------------- bpgetcrc proc test flgs, flgrcv ; q. character received? jnz bpgcrc10 ; a. yes .. check it out mov bx, CHRTMOUT ; bx = character timeout call chktimer ; q. timeout? jz bpgcrc90 ; a. no .. continue XSTATE $ST_SNDNAK ; send a NAK bpgcrc10: mov bx, rcvaddr ; bx -> received char mov al, [bx] ; al = char received test bpflg, bpfqut ; q. quoting active? jz bpgcrc50 ; a. no .. check/save char and bpflg, not bpfqut ; .. reset quoting flag cmp al, 60h ; q. 80-9f range? pushf ; .. save the answer and al, 1fh ; .. upper bits off popf ; .. restore answer .. jb bpgcrc70 ; a. no .. store as is add al, 80h ; else.. reconstitute 80-9f jmp short bpgcrc70 ; .. and save it bpgcrc50: cmp al, $DLE ; q. quoted char? jne bpgcrc70 ; a. no .. continue and flgs, not flgrcv ; "receive" the quote or bpflg, bpfqut ; show quoted char expected XSTATE ; .. and say in state bpgcrc70: and flgs, not flgrcv ; show byte processed mov ckbyte2, al ; save as CRC byte 2 NSTATE $ST_VERCRC ; .. assume CRC checking bpgcrc90: XSTATE ; .. continue bpgetcrc endp ; --------------------------------------------------------------------- ; Verify Checksum ; --------------------------------------------------------------------- bpvercks proc lea si, packet ; si -> packet mov cx, rcvaddr ; cx -> next to receive sub cx, si ; cx = length to check call bpcksum ; dx = calc'd chksum cmp dl, chksumval ; q. does it match? je bpvercks90 ; a. yes .. exit AOK! XSTATE $ST_SNDNAK ; else .. send a NAK bpvercks90: NSTATE $ST_VERPKT ; .. continue bpvercks endp ; --------------------------------------------------------------------- ; Verify CRC ; --------------------------------------------------------------------- bpvercrc proc lea si, packet ; si -> packet mov cx, rcvaddr ; cx -> next to receive sub cx, si ; cx = length to check call bpcrc ; dl = calc'd crc cmp dx, crcval ; q. does it match? je bpvercrc90 ; a. yes .. exit AOK! XSTATE $ST_SNDNAK ; else .. send a NAK bpvercrc90: NSTATE $ST_VERPKT ; .. continue bpvercrc endp ; --------------------------------------------------------------------- ; Verify packet ; --------------------------------------------------------------------- bpverpkt proc mov al, packet ; al = sequence number mov ah, bpseq ; ah = last good sequence inc ah ; ah = next seq number cmp ah, '9' ; q. did seq wrap? jna bpverpkt05 ; a. no .. continue mov ah, '0' ; ah = next packet number bpverpkt05: cmp al, ah ; q. expected number? jne bpverpkt10 ; a. no .. check it out mov errors, 0 ; reset error count or flgs, flgrec ; show record received XSTATE $ST_SNDACK ; else .. exit the state bpverpkt10: cmp packet+1, 'F' ; q. Fail packet? jne bpverpkt20 ; a. no .. continue or flgs, flgrec ; show record received XSTATE ; else .. exit the state bpverpkt20: cmp al, bpseq ; q. previous packet? jne bpverpkt40 ; a. no .. NAK it NSTATE $ST_SNDACK ; .. ack the pak bpverpkt40: NSTATE $ST_SNDNAK ; .. nak that pak! bpverpkt endp ; --------------------------------------------------------------------- ; Send an ACK ; --------------------------------------------------------------------- bpsndack proc mov bl, $DLE ; bl = DLE mov di, 20 ; di = send one char call callback ; .. ask BD to do it mov bl, bpseq ; bl = sequence number mov di, 20 ; di = send one char call callback ; .. ask BD to do it mov bl, '.' ; bl = I'm alive char mov di, 14 ; di = display one char call callback ; .. ask BD to do it mov bx, PKTTMOUT ; set packet timeout call setimer ; set the timer and flgs, not flgtmo ; .. reset timeout mov rcvaddr, offset packet ; .. reset the receive addr XSTATE $ST_GETDLE ; get a DLE bpsndack endp ; --------------------------------------------------------------------- ; Send a NAK ; --------------------------------------------------------------------- bpsndnak proc cmp errors, MAXERRS ; q. too many errors? jb bpsndnak10 ; a. no .. continue lea bx, toomany ; bx -> too many errors msg jmp proto_err ; .. exit the protocol bpsndnak10: mov bl, $NAK ; bl = NAK mov di, 20 ; di = send one char call callback ; .. ask BD to do it mov bl, 'X' ; bl = I'm nakking char mov di, 14 ; di = display one char call callback ; .. ask BD to do it mov bx, PKTTMOUT ; set packet timeout call setimer ; set the timer and flgs, not flgtmo ; .. reset timeout mov rcvaddr, offset packet ; .. reset the receive addr XSTATE $ST_GETDLE ; get a DLE bpsndnak endp ; --------------------------------------------------------------------- ; Send a panic abort ; --------------------------------------------------------------------- panic proc push bx ; save caller's bx lea bx, panicmsg ; bx -> panic stop msg mov di, 18 ; di = send one char call callback ; .. ask BD to do it pop bx ; restore caller's bx ret ; return to caller panic endp ; --------------------------------------------------------------------- ; Check for timeout non-zero = timeout ; --------------------------------------------------------------------- chktimer proc test flgs, flgtmo ; set zf if no timeout pushf ; save flags jz chktimer10 ; .. jump if no timeout call setimer ; set 10 second value chktimer10: popf ; restore test results ret ; .. return to caller chktimer endp ; --------------------------------------------------------------------- ; Set timer to 10 second timeout bx = ticks to wait ; --------------------------------------------------------------------- setimer proc mov di, 22 ; di = set tick downcounter call callback ; .. have BD do it ret ; .. return to caller setimer endp ; --------------------------------------------------------------------- ; Check errors bx -> error message ; --------------------------------------------------------------------- chk_err proc inc errors ; add one to errors cmp errors, MAXERRS ; q. too many errors? jb chk_err10 ; a. no .. continue jmp proto_err ; .. kill the protocol chk_err10: XSTATE ; .. continue the protocol chk_err endp ; --------------------------------------------------------------------- ; Show received character processed ; --------------------------------------------------------------------- charcvd proc and flgs, not flgrcv ; shut off receive bit inc rcvaddr ; point to next address ret ; return to caller charcvd endp ; ---------------------------------------------------------------------- ; Calculate standard B protocol checksum ; ; entry: si -> block to check ; cx = length ; exit: dl = checksum ; ---------------------------------------------------------------------- bpcksum proc push cx ; save register xor ah, ah ; ah = zero for additions xor dx, dx ; dx = zero for accumulator bpcksum10: shl dx, 1 ; dx = shifted left by 1 cmp dx, 0ffh ; q. over 255? jle bpcksum20 ; a. no .. continue and dx, 0ffh ; dx = less than 255 inc dx ; ..plus one bpcksum20: lodsb ; al = char from buffer add dx, ax ; dx = acculation of chars cmp dx, 0ffh ; q. over 255? jle bpcksum30 ; a. no .. continue and dx, 0ffh ; dx = less than 255 inc dx ; ..plus one bpcksum30: loop bpcksum10 ; loop back till done pop cx ; ..restore register ret ; ..then return to caller bpcksum endp ; ---------------------------------------------------------------------- ; Calculate CRC entry: si -> message block ; cx = length of message ; exit: dx = returned CRC ; ---------------------------------------------------------------------- bpcrc proc push bx ; save registers push cx push di mov dx, -1 ; dx = initialize crc mov bx, 1021h ; bx = working constant mov di, 8000h ; di = constant, too bpcrc10: lodsb ; al = char from message xor ah, ah ; ax = cast char as integer xchg al, ah ; shift left char by 8 xor dx, ax ; crc ^= (int)*ptr++ << 8 push cx ; save register mov cx, 8 ; cx = bit loop count bpcrc20: mov ax, dx ; ax = temp copy of crc and ax, di ; q. bit on? jz bpcrc30 ; a. no .. continue shl dx, 1 ; shift left by one bit xor dx, bx ; crc = crc << 1 ^ 0x1021 jmp short bpcrc40 ; ..continue with common code bpcrc30: shl dx, 1 ; crc <<= 1 bpcrc40: loop bpcrc20 ; ..just loop thru this byte pop cx ; restore register loop bpcrc10 ; ..and loop thru whole message pop di ; restore registers pop cx pop bx ret ; return to caller bpcrc endp ; ---------------------------------------------------------------------- ; Setup output field ; - with count ; - DLE + "B" ; - move in data, applying quouting rules ; - call CRC/cksum routines ; ; entry: si -> user data w/terminating ETX ; di -> destination area ; cx = length ; exit: di -> 2byte length + data + CRC/cksum ; ---------------------------------------------------------------------- bd_setout proc push di ; save registers xor bx, bx ; bx = extra DLE bytes added mov ax, cx ; get copy of length stosw ; store in output record push si ; save registers test bpflg, bpfcrc ; q. using CRC? jz bd_seto20 ; a. no .. calculate chksum call bpcrc ; dx = CRC of the data add bx, 2 ; bx = 2 extra bytes jmp short bd_seto30 ; ..continue w/common code bd_seto20: call bpcksum ; dl = checksum of data inc bx ; bx = 1 extra byte bd_seto30: pop si ; restore register push dx ; save CRC/checksum mov ax, 4210h ; ax = DLE + "B" stosw ; save in output record add bx, 2 ; bx = 2 more bytes mov dx, bx ; dx = extra length, now dec cx ; cx = len - 1, for ETX's sake bd_seto40: lodsb ; al = source byte cmp al, 1fh ; q. in the 1st range? ja bd_seto50 ; a. no .. continue xor ah, ah ; ax = (int) source byte mov bx, ax ; bx = index into quote array cmp bpqc00[bx], 0 ; q. need to quote char? je bd_seto70 ; a. no .. continue add al, 40h ; al = quoted character jmp short bd_seto60 ; ..do rest of quoting stuff bd_seto50: cmp al, 80h ; q. maybe in 2nd range? jb bd_seto70 ; a. no .. normal character cmp al, 9fh ; q. really in 2nd range? ja bd_seto70 ; a. no .. must be normal and al, 1fh ; al = 00 - 1fh xor ah, ah ; ax = (int) source byte mov bx, ax ; bx = index into quote array cmp bpqc80[bx], 0 ; q. need to quote char? je bd_seto70 ; a. no .. continue add al, 60h ; al = quoted character bd_seto60: mov ah, 10h ; ah = DLE xchg al, ah ; swap around for store stosw ; ..save in output record inc dx ; dx = one more extra char jmp short bd_seto80 ; ..continue w/common code bd_seto70: stosb ; save char in output area bd_seto80: loop bd_seto40 ; ..then loop till done movsb ; copy ETX to output area pop ax ; ax = CRC/checksum stosw ; save one or the other pop di ; di -> output count add [di], dx ; add in "extra" bytes cnt ret ; ..finally, return to caller bd_setout endp ; ---------------------------------------------------------------------- ; Unroll set quote mode fields ; ; entry: si -> source field of 8 bytes ; di -> destination field of 64 bytes ; ---------------------------------------------------------------------- bd_setq proc mov cx, 8 ; cx = big loop size bd_setq10: push cx ; save outer loop size mov cx, 8 ; cx = bits per byte lodsb ; al = source byte mov ah, al ; ah = work value bd_setq20: test ah, 80h ; q. bit set? jz bd_setq30 ; a. no .. clear dest byte mov al, 0ffh ; al = true value jmp short bd_setq40 ; ..continue w/common code bd_setq30: xor al, al ; al = false value bd_setq40: stosb ; save in destination array shl ah, 1 ; ah = next bit to test loop bd_setq20 ; ..loop till byte done pop cx ; restore outer loop count loop bd_setq10 ; ..loop till array finished ret ; ..finally, return to caller bd_setq endp ; --------------------------------------------------------------------- ; Set bpseq to next sequence number ; --------------------------------------------------------------------- nxtseq proc inc bpseq ; increment seq number cmp bpseq, '9' ; q. rollover? jna nxtseq90 ; a. no .. exit mov bpseq, '0' ; .. else return to '0' nxtseq90: ret ; .. return to caller nxtseq endp ; --------------------------------------------------------------------- ; Setup to "call" backdown di = return code ; --------------------------------------------------------------------- callback proc or flgs, flgfnc ; show were in callback mode jmp short proto_exit ; return to caller callback endp ; --------------------------------------------------------------------- ; Display error, return done bx -> string ; --------------------------------------------------------------------- proto_err proc mov di, 12 ; di = display string call callback ; .. display it jmp short proto_done ; tell bd we are done proto_err endp ; --------------------------------------------------------------------- ; Protocol done - leave forever ; --------------------------------------------------------------------- proto_done proc push ds ; save our ds les di, ubp_area ; es:di -> caller' area lea si, bparea ; ds:di -> our area mov cx, 5 ; words to move cld ; ascending rep movsw ; .. return 'em to user pop ds ; restore our DS mov di, 10 ; di = done code jmp short proto_exit ; leave the protocol proto_done endp ; --------------------------------------------------------------------- ; Exit with the OK code ; --------------------------------------------------------------------- proto_ok proc and flgs, not flgfnc ; zero out the function flag mov di, 0 ; di = ok return code jmp short proto_exit ; restore regs & exit proto_ok endp ; --------------------------------------------------------------------- ; Protcol exit routine ; --------------------------------------------------------------------- proto_exit proc mov stackoffset, sp ; save our stack offset cli ; no interrupts mov ss, oldss ; ..restore callers ss mov sp, oldsp ; ..and sp sti ; ints ok again pop ds ; restore caller's regs pop es FARRET ; return to caller proto_exit endp protocol ends end start