1$Id: INTERFACE.fax,v 1.2 2000/08/06 09:22:50 armin Exp $
2
3
4Description of the fax-subinterface between linklevel and hardwarelevel of 
5  isdn4linux. 
6
7  The communication between linklevel (LL) and hardwarelevel (HL) for fax
8  is based on the struct T30_s (defined in isdnif.h).
9  This struct is allocated in the LL.  
10  In order to use fax, the LL provides the pointer to this struct with the 
11  command ISDN_CMD_SETL3 (parm.fax). This pointer expires in case of hangup 
12  and when a new channel to a new connection is assigned. 
13
14
15Data handling:
16  In send-mode the HL-driver has to handle the <DLE> codes and the bit-order 
17  conversion by itself. 
18  In receive-mode the LL-driver takes care of the bit-order conversion
19  (specified by +FBOR)
20
21Structure T30_s description:
22
23  This structure stores the values (set by AT-commands), the remote-
24  capability-values and the command-codes between LL and HL.
25
26  If the HL-driver receives ISDN_CMD_FAXCMD, all needed information
27  is in this struct set by the LL.
28  To signal information to the LL, the HL-driver has to set the 
29  parameters and use ISDN_STAT_FAXIND.
30  (Please refer to INTERFACE)
31
32Structure T30_s:
33
34  All members are 8-bit unsigned (__u8)
35
36  -  resolution     
37  -  rate
38  -  width
39  -  length
40  -  compression
41  -  ecm
42  -  binary
43  -  scantime
44  -  id[]
45  Local faxmachine's parameters, set by +FDIS, +FDCS, +FLID, ...
46
47  -  r_resolution
48  -  r_rate
49  -  r_width
50  -  r_length
51  -  r_compression
52  -  r_ecm
53  -  r_binary
54  -  r_scantime
55  -  r_id[]
56  Remote faxmachine's parameters. To be set by HL-driver.
57
58  -  phase      
59  Defines the actual state of fax connection. Set by HL or LL
60  depending on progress and type of connection.
61  If the phase changes because of an AT command, the LL driver
62  changes this value. Otherwise the HL-driver takes care of it, but
63  only necessary on call establishment (from IDLE to PHASE_A).
64  (one of the constants ISDN_FAX_PHASE_[IDLE,A,B,C,D,E])
65
66  -  direction
67  Defines outgoing/send or incoming/receive connection.
68  (ISDN_TTY_FAX_CONN_[IN,OUT])
69
70  -  code
71  Commands from LL to HL; possible constants : 
72      ISDN_TTY_FAX_DR        signals +FDR command to HL
73
74      ISDN_TTY_FAX_DT        signals +FDT command to HL 
75
76      ISDN_TTY_FAX_ET        signals +FET command to HL
77
78
79  Other than that the "code" is set with the hangup-code value at
80  the end of connection for the +FHNG message.
81        
82  -  r_code 
83  Commands from HL to LL; possible constants :
84      ISDN_TTY_FAX_CFR       output of +FCFR message. 
85
86      ISDN_TTY_FAX_RID       output of remote ID set in r_id[]
87                             (+FCSI/+FTSI on send/receive)
88
89      ISDN_TTY_FAX_DCS       output of +FDCS and CONNECT message,
90                             switching to phase C.
91
92      ISDN_TTY_FAX_ET        signals end of data,
93                             switching to phase D.
94
95      ISDN_TTY_FAX_FCON      signals the established, outgoing connection,
96                             switching to phase B.
97
98      ISDN_TTY_FAX_FCON_I    signals the established, incoming connection,
99                             switching to phase B.
100
101      ISDN_TTY_FAX_DIS       output of +FDIS message and values.
102
103      ISDN_TTY_FAX_SENT      signals that all data has been sent 
104                             and <DLE><ETX> is acknowledged,
105                             OK message will be sent.
106
107      ISDN_TTY_FAX_PTS       signals a msg-confirmation (page sent successful),
108                             depending on fet value:
109                             0: output OK message (more pages follow)
110                             1: switching to phase B (next document)
111
112      ISDN_TTY_FAX_TRAIN_OK  output of +FDCS and OK message (for receive mode).
113
114      ISDN_TTY_FAX_EOP       signals end of data in receive mode,
115                             switching to phase D.
116
117      ISDN_TTY_FAX_HNG       output of the +FHNG and value set by code and
118                             OK message, switching to phase E.
119
120
121  -  badlin
122  Value of +FBADLIN  
123
124  -  badmul
125  Value of +FBADMUL
126
127  -  bor
128  Value of +FBOR
129
130  -  fet
131  Value of +FET command in send-mode.
132  Set by HL in receive-mode for +FET message.
133
134  -  pollid[]  
135  ID-string, set by +FCIG
136
137  -  cq
138  Value of +FCQ
139
140  -  cr
141  Value of +FCR
142
143  -  ctcrty
144  Value of +FCTCRTY
145
146  -  minsp
147  Value of +FMINSP
148
149  -  phcto
150  Value of +FPHCTO
151
152  -  rel
153  Value of +FREL
154
155  -  nbc
156  Value of +FNBC (0,1)
157  (+FNBC is not a known class 2 fax command, I added this to change the
158   automatic "best capabilities" connection in the eicon HL-driver)
159
160  
161Armin
162mac@melware.de
163
164