ref: da7d6df6faf18e289fe0f3f61524dcc7fddeef18
dir: /appl/examples/minitel/modem.b/
#
# Copyright © 1998 Vita Nuova Limited. All rights reserved.
#
#modem states for direct connection
MSstart, MSdialing, MSconnected, MSdisconnecting,
# special features
Ecp # error correction
: con (1 << iota);
Ecplen: con 17; # error correction block length: data[15], crc, validation (=0)
Modem: adt {
m: ref Module; # common attributes
in: chan of ref Event;
connect: int; # None, Direct, Network
state: int; # modem dialing state
saved: string; # response, so far (direct dial)
initstr: string; # softmodem init string (direct dial)
dialstr: string; # softmodem dial string (direct dial)
lastdialstr: string;
spec: int; # special features
fd: ref Sys->FD; # modem data file, if != nil
cfd: ref Sys->FD; # modem ctl file, if != nil (direct dial only)
devpath: string; # path to the modem;
avail: array of byte; # already read
rd: chan of array of byte; # reader -> rd
pid: int; # reader pid if != 0
seq: int; # ECP block sequence number
waitsyn: int; # awaiting restart SYN SYN ... sequence
errforce: int;
addparity: int; # must add parity to outgoing data
init: fn(m: self ref Modem, connect: int, initstr, dialstr: string);
reset: fn(m: self ref Modem);
run: fn(m: self ref Modem);
quit: fn(m: self ref Modem);
runstate: fn(m: self ref Modem, data: array of byte);
write: fn(m: self ref Modem, data: array of byte):int; # to network
reader: fn(m: self ref Modem, pidc: chan of int);
};
partab: array of byte;
dump(a: array of byte, n: int): string
{
s := sys->sprint("[%d]", n);
for(i := 0; i < n; i++)
s += sys->sprint(" %.2x", int a[i]);
return s;
}
Modem.init(m: self ref Modem, connect: int, initstr, dialstr: string)
{
partab = array[128] of byte;
for(c := 0; c < 128; c++)
if(parity(c))
partab[c] = byte (c | 16r80);
else
partab[c] = byte c;
m.in = chan of ref Event;
m.connect = connect;
m.state = MSstart;
m.initstr = initstr;
m.dialstr = dialstr;
m.pid = 0;
m.spec = 0;
m.seq = 0;
m.waitsyn = 0;
m.errforce = 0;
m.addparity = 0;
m.avail = array[0] of byte;
m.rd = chan of array of byte;
m.reset();
}
Modem.reset(m: self ref Modem)
{
m.m = ref Module(Pscreen, 0);
}
Modem.run(m: self ref Modem)
{
if(m.dialstr != nil)
send(ref Event.Eproto(Pmodem, Mmodem, Cconnect, "", 0,0,0));
Runloop:
for(;;){
alt {
ev := <- m.in =>
pick e := ev {
Equit =>
break Runloop;
Edata =>
if(debug['m'] > 0)
fprint(stderr, "Modem <- %s\n", e.str());
m.write(e.data);
if(T.state == Local || T.spec & Echo) { # loopback
if(e.from == Mkeyb) {
send(ref Event.Eproto(Pscreen, Mkeyb, Ccursor, "", 0,0,0));
send(ref Event.Edata(Pscreen, Mkeyb, e.data));
}
}
Eproto =>
case e.cmd {
Creset =>
m.reset();
Cconnect =>
if(m.pid != 0)
break;
m.addparity = 1;
T.state = Connecting;
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
case m.connect {
Direct =>
S.msg("Appel "+m.dialstr+" ...");
dev := "/dev/modem";
if(openmodem(m, dev) < 0) {
S.msg("Modem non prêt");
T.state = Local;
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
break;
}
m.state = MSdialing;
m.saved = "";
dialout(m);
T.terminalid = TERMINALID2;
Network =>
S.msg("Connexion au serveur ...");
if(debug['m'] > 0 || debug['M'] > 0)
sys->print("dial(%s)\n", m.dialstr);
cx := dial->dial(m.dialstr, "");
if (cx == nil){
S.msg("Echec de la connexion");
T.state = Local;
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
if(debug['m'] > 0)
sys->print("can't dial %s: %r\n", m.dialstr);
break;
}
m.fd = cx.dfd;
m.cfd = cx.cfd;
if(len m.dialstr >= 3 && m.dialstr[0:3] == "tcp")
m.addparity = 0; # Internet gateway apparently doesn't require parity
if(m.fd != nil) {
S.msg(nil);
m.state = MSconnected;
T.state = Online;
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
}
T.terminalid = TERMINALID1;
}
if(m.fd != nil) {
pidc := chan of int;
spawn m.reader(pidc);
m.pid = <-pidc;
}
Cdisconnect =>
if(m.pid != 0) {
S.msg("Déconnexion ...");
m.state = MSdisconnecting;
}
if(m.connect == Direct)
hangup(m);
else
nethangup(m);
Cplay => # for testing
case e.s {
"play" =>
replay(m);
}
Crequestecp =>
if(m.spec & Ecp){ # for testing: if already active, force an error
m.errforce = 1;
break;
}
m.write(array[] of {byte SEP, byte 16r4A});
sys->print("sending request for ecp\n");
Cstartecp =>
m.spec |= Ecp;
m.seq = 0; # not in spec
m.waitsyn = 0; # not in spec
Cstopecp =>
m.spec &= ~Ecp;
* => break;
}
}
b := <- m.rd =>
if(debug['m'] > 0){
fprint(stderr, "Modem -> %s\n", dump(b,len b));
}
if(b == nil) {
m.pid = 0;
case m.state {
MSdialing =>
S.msg("Echec appel");
MSdisconnecting =>
S.msg(nil);
}
m.state = MSstart;
T.state = Local;
send(ref Event.Eproto(Pscreen, Mmodem, Cscreenon, "",0,0,0));
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
break;
}
m.runstate(b);
}
}
if(m.pid != 0)
kill(m.pid);
send(nil);
}
Modem.quit(nil: self ref Modem)
{
}
Modem.runstate(m: self ref Modem, data: array of byte)
{
if(debug['m']>0)
sys->print("runstate %d %s\n", m.state, dump(data, len data));
case m.state {
MSstart => ;
MSdialing =>
for(i:=0; i<len data; i++) {
ch := int data[i];
if(ch != '\n' && ch != '\r') {
m.saved[len m.saved] = ch;
continue;
}
(code, str) := seenreply(m.saved);
case code {
Noise or Ok => ;
Success =>
S.msg(nil);
m.state = MSconnected;
T.state = Online;
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
Failure =>
hangup(m);
S.msg(str);
m.state = MSstart;
T.state = Local;
send(ref Event.Eproto(Pscreen, Mmodem, Cindicators, "",0,0,0));
}
m.saved = "";
}
MSconnected =>
send(ref Event.Edata(m.m.path, Mmodem, data));
MSdisconnecting => ;
}
}
Modem.write(m: self ref Modem, data: array of byte): int
{
if(m.fd == nil)
return -1;
if(len data == 0)
return 0;
if(m.addparity){
# unfortunately must copy data to add parity for direct modem connection
pa := array[len data] of byte;
for(i := 0; i<len data; i++)
pa[i] = partab[int data[i] & 16r7F];
data = pa;
}
if(debug['m']>0)
sys->print("WRITE %s\n", dump(data, len data));
return sys->write(m.fd, data, len data);
}
#
# minitel error correction protocol
#
# SYN, SYN, block number start of retransmission
# NUL ignored
# DLE escapes {DLE, SYN, NACK, NUL}
# NACK, block restart request
#
crctab: array of int;
Crcpoly: con 16r9; # crc7 = x^7+x^3+1
# precalculate the CRC7 remainder for all bytes
mktabs()
{
crctab = array[256] of int;
for(c := 0; c < 256; c++){
v := c;
crc := 0;
for(i := 0; i < 8; i++){
crc <<= 1; # align remainder's MSB with value's
if((v^crc) & 16r80)
crc ^= Crcpoly;
v <<= 1;
}
crctab[c] = (crc<<1) & 16rFE; # pre-align the result to save <<1 later
}
}
# return the index of the first non-NUL character (the start of a block)
nextblock(a: array of byte, i: int, n: int): int
{
for(; i < n; i++)
if(a[i] != byte NUL)
break;
return i;
}
# return the data in the ecp block in a[0:Ecplen] (return nil for bad format)
decode(a: array of byte): array of byte
{
if(debug['M']>0)
sys->print("DECODE: %s\n", dump(a, Ecplen));
badpar := 0;
oldcrc := int a[Ecplen-2];
crc := 0;
op := 0;
dle := 0;
for(i:=0; i<Ecplen-2; i++){ # first byte is high-order byte of polynomial (MSB first)
c := int a[i];
nc := c & 16r7F; # strip parity
if((c^int partab[nc]) & 16r80)
badpar++;
crc = crctab[crc ^ c];
# collapse DLE sequences
if(!dle){
if(nc == DLE && i+1 < Ecplen-2){
dle = 1;
continue;
}
if(nc == NUL)
continue; # strip non-escaped NULs
}
dle = 0;
a[op++] = byte nc;
}
if(badpar){
if(debug['E'] > 0)
sys->print("bad parity\n");
return nil;
}
crc = (crc>>1)&16r7F;
if(int partab[crc] != oldcrc){
if(debug['E'] > 0)
sys->print("bad crc: in %ux got %ux\n", oldcrc, int partab[crc]);
return nil;
}
b := array[op] of byte;
b[0:] = a[0:op];
if(debug['M'] > 0)
sys->print("OUT: %s [%x :: %x]\n", dump(b,op), crc, oldcrc);
return b;
}
Modem.reader(m: self ref Modem, pidc: chan of int)
{
pidc <-= sys->pctl(0, nil);
if(crctab == nil)
mktabs();
a := array[Sys->ATOMICIO] of byte;
inbuf := 0;
while(m.fd != nil) {
while((n := read(m.fd, a[inbuf:], len a-inbuf)) > 0){
n += inbuf;
inbuf = 0;
if((m.spec & Ecp) == 0){
b := array[n] of byte;
for(i := 0; i<n; i++)
b[i] = byte (int a[i] & 16r7F); # strip parity
m.rd <-= b;
}else{
#sys->print("IN: %s\n", dump(a,n));
i := 0;
if(m.waitsyn){
sys->print("seeking SYN #%x\n", m.seq);
syn := byte (SYN | 16r80);
lim := n-3;
for(; i <= lim; i++)
if(a[i] == syn && a[i+1] == syn && (int a[i+2]&16r0F) == m.seq){
i += 3;
m.waitsyn = 0;
sys->print("found SYN #%x@%d\n", m.seq, i-3);
break;
}
}
lim := n-Ecplen;
for(; (i = nextblock(a, i, n)) <= lim; i += Ecplen){
b := decode(a[i:]);
if(m.errforce || b == nil){
m.errforce = 0;
b = array[2] of byte;
b[0] = byte NACK;
b[1] = byte (m.seq | 16r40);
sys->print("NACK #%x\n", m.seq);
m.write(b);
m.waitsyn = 1;
i = n; # discard rest of block
break;
}
m.seq = (m.seq+1) & 16rF; # mod 16 counter
m.rd <-= b;
}
if(i < n){
a[0:] = a[i:n];
inbuf = n-i;
}
}
}
if(n <= 0)
break;
}
# m.fd = nil;
m.rd <-= nil;
}
playfd: ref Sys->FD;
in_code, in_char: con iota;
replay(m: ref Modem)
{
buf := array[8192] of byte;
DMAX: con 10;
d := 0;
da := array[DMAX] of byte;
playfd = nil;
if(playfd == nil)
playfd = sys->open("minitel.txt", Sys->OREAD);
if(playfd == nil)
return;
nl := 1;
discard := 1;
state := in_code;
hs := "";
start := 0;
mainloop:
for(;;) {
n := sys->read(playfd, buf, len buf);
if(n <= 0)
break;
for(i:=0; i<n; i++) {
ch := int buf[i];
if(nl)
case ch {
'>' => discard = 0;
'<' => discard = 1;
if(start)
sys->sleep(1000);
'{' => start = 1;
'}' => break mainloop;
}
if(ch == '\n')
nl = 1;
else
nl = 0;
if(discard)
continue;
if(!start)
continue;
if(state == in_code && ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'z')))
hs[len hs] = ch;
else if(ch == '(') {
state = in_char;
(v, nil) := toint(hs, 16);
da[d++] = byte v;
if(d == DMAX) {
send(ref Event.Edata(m.m.path, Mmodem, da));
d = 0;
da = array[DMAX] of byte;
sys->sleep(50);
}
hs = "";
}else if(ch == ')')
state = in_code;
}
}
playfd = nil;
}
kill(pid : int)
{
prog := "#p/" + string pid + "/ctl";
fd := sys->open(prog, Sys->OWRITE);
if (fd != nil) {
cmd := array of byte "kill";
sys->write(fd, cmd, len cmd);
}
}
# Modem stuff
# modem return codes
Ok, Success, Failure, Noise, Found: con iota;
#
# modem return messages
#
Msg: adt {
text: string;
trans: string;
code: int;
};
msgs: array of Msg = array [] of {
("OK", "Ok", Ok),
("NO CARRIER", "No carrier", Failure),
("ERROR", "Bad modem command", Failure),
("NO DIALTONE", "No dial tone", Failure),
("BUSY", "Busy tone", Failure),
("NO ANSWER", "No answer", Failure),
("CONNECT", "", Success),
};
msend(m: ref Modem, x: string): int
{
a := array of byte x;
return sys->write(m.fd, a, len a);
}
#
# apply a string of commands to modem
#
apply(m: ref Modem, s: string): int
{
buf := "";
for(i := 0; i < len s; i++){
c := s[i];
buf[len buf] = c; # assume no Unicode
if(c == '\r' || i == (len s -1)){
if(c != '\r')
buf[len buf] = '\r';
if(msend(m, buf) < 0)
return Failure;
buf = "";
}
}
return Ok;
}
openmodem(m: ref Modem, dev: string): int
{
m.fd = sys->open(dev, Sys->ORDWR);
m.cfd = sys->open(dev+"ctl", Sys->ORDWR);
if(m.fd == nil || m.cfd == nil)
return -1;
# hangup(m);
# m.fd = sys->open(dev, Sys->ORDWR);
# m.cfd = sys->open(dev+"ctl", Sys->ORDWR);
# if(m.fd == nil || m.cfd == nil)
# return -1;
return 0;
}
hangup(m: ref Modem)
{
sys->sleep(1020);
msend(m, "+++");
sys->sleep(1020);
apply(m, "ATH0");
m.fd = nil;
# sys->write(m.cfd, array of byte "f", 1);
sys->write(m.cfd, array of byte "h", 1);
m.cfd = nil;
# HACK: shannon softmodem "off-hook" bug fix
sys->open("/dev/modem", Sys->OWRITE);
}
nethangup(m: ref Modem)
{
m.fd = nil;
sys->write(m.cfd, array of byte "hangup", 6);
m.cfd = nil;
}
#
# check `s' for a known reply or `substr'
#
seenreply(s: string): (int, string)
{
for(k := 0; k < len msgs; k++)
if(len s >= len msgs[k].text && s[0:len msgs[k].text] == msgs[k].text) {
return (msgs[k].code, msgs[k].trans);
}
return (Noise, s);
}
contains(s, t: string): int
{
if(t == nil)
return 1;
if(s == nil)
return 0;
n := len t;
for(i := 0; i+n <= len s; i++)
if(s[i:i+n] == t)
return 1;
return 0;
}
dialout(m: ref Modem)
{
if(m.initstr != nil)
apply(m, "AT"+m.initstr);
if(m.dialstr != nil) {
apply(m, "ATD"+m.dialstr);
m.lastdialstr = m.dialstr;
m.dialstr = nil;
}
}