spandsp  0.0.6
private/t38_gateway.h
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1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * private/t38_gateway.h - A T.38, less the packet exchange part
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2005, 2006, 2007 Steve Underwood
9  *
10  * All rights reserved.
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU Lesser General Public License version 2.1,
14  * as published by the Free Software Foundation.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU Lesser General Public License for more details.
20  *
21  * You should have received a copy of the GNU Lesser General Public
22  * License along with this program; if not, write to the Free Software
23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24  */
25 
26 /*! \file */
27 
28 #if !defined(_SPANDSP_PRIVATE_T38_GATEWAY_H_)
29 #define _SPANDSP_PRIVATE_T38_GATEWAY_H_
30 
31 /*!
32  T.38 gateway T.38 side channel descriptor.
33 */
34 typedef struct
35 {
36  /*! \brief Core T.38 IFP support */
38 
39  /*! \brief TRUE if the NSF, NSC, and NSS are to be suppressed by altering
40  their contents to something the far end will not recognise. */
41  int suppress_nsx_len[2];
42  /*! \brief TRUE if we need to corrupt the HDLC frame in progress, so the receiver cannot
43  interpret it. The two values are for the two directions. */
44  int corrupt_current_frame[2];
45 
46  /*! \brief the current class of field being received - i.e. none, non-ECM or HDLC */
48  /*! \brief The T.38 indicator currently in use */
50 
51  /*! \brief The current T.38 data type being sent. */
54 
55 /*!
56  T.38 gateway audio side channel descriptor.
57 */
58 typedef struct
59 {
60  /*! \brief The FAX modem set for the audio side fo the gateway. */
62  /*! \brief The current receive signal handler. Actual receiving hops between this
63  and a dummy receive routine. */
64  span_rx_handler_t *base_rx_handler;
65  span_rx_fillin_handler_t *base_rx_fillin_handler;
67 
68 /*!
69  T.38 gateway T.38 side state.
70 */
71 typedef struct
72 {
73  /*! \brief non-ECM and HDLC modem receive data buffer. */
74  uint8_t data[T38_RX_BUF_LEN];
75  /*! \brief Current pointer into the data buffer. */
76  int data_ptr;
77  /*! \brief The current octet being received as non-ECM data. */
78  unsigned int bit_stream;
79  /*! \brief The number of bits taken from the modem for the current scan row. This
80  is used during non-ECM transmission will fill bit removal to see that
81  T.38 packet transmissions do not stretch too far apart. */
83  /*! \brief The current bit number in the current non-ECM octet. */
84  int bit_no;
85  /*! \brief Progressively calculated CRC for HDLC messages received from a modem. */
86  uint16_t crc;
87  /*! \brief TRUE if non-ECM fill bits are to be stripped when sending image data. */
89  /*! \brief The number of octets to send in each image packet (non-ECM or ECM) at the current
90  rate and the current specified packet interval. */
92 
93  /*! \brief Bits into the non-ECM buffer */
94  int in_bits;
95  /*! \brief Octets fed out from the non-ECM buffer */
98 
99 /*!
100  T.38 gateway HDLC buffer.
101 */
102 typedef struct
103 {
104  /*! \brief HDLC message buffers. */
105  uint8_t buf[T38_MAX_HDLC_LEN];
106  /*! \brief HDLC message lengths. */
107  int len;
108  /*! \brief HDLC message status flags. */
109  int flags;
110  /*! \brief HDLC buffer contents. */
111  int contents;
113 
114 /*!
115  T.38 gateway HDLC state.
116 */
117 typedef struct
118 {
119  /*! \brief HDLC message buffers. */
121 #if 0
122  /*! \brief HDLC message buffers. */
123  uint8_t buf[T38_TX_HDLC_BUFS][T38_MAX_HDLC_LEN];
124  /*! \brief HDLC message lengths. */
125  int len[T38_TX_HDLC_BUFS];
126  /*! \brief HDLC message status flags. */
127  int flags[T38_TX_HDLC_BUFS];
128  /*! \brief HDLC buffer contents. */
129  int contents[T38_TX_HDLC_BUFS];
130 #endif
131  /*! \brief HDLC buffer number for input. */
132  int in;
133  /*! \brief HDLC buffer number for output. */
134  int out;
136 
137 /*!
138  T.38 gateway core descriptor.
139 */
140 typedef struct
141 {
142  /*! \brief A bit mask of the currently supported modem types. */
144  /*! \brief TRUE if ECM FAX mode is allowed through the gateway. */
146  /*! \brief Required time between T.38 transmissions, in ms. */
148 
149  /*! \brief TRUE if in image data modem is to use short training. This usually
150  follows image_data_mode, but in ECM mode T.30 defines recovery
151  conditions in which long training is used for image data. */
153  /*! \brief TRUE if in image data mode, as opposed to TCF mode. */
155  /*! \brief The minimum permitted bits per FAX scan line row. */
157 
158  /*! \brief TRUE if we should count the next MCF as a page end, else FALSE */
160  /*! \brief The number of pages for which a confirm (MCF) message was returned. */
162 
163  /*! \brief TRUE if we are in error correcting (ECM) mode */
164  int ecm_mode;
165  /*! \brief The current bit rate for the fast modem. */
167  /*! \brief The current fast receive modem type. */
169  /*! \brief The type of fast receive modem currently active, which may be T38_NONE */
171 
172  /*! \brief The current timed operation. */
174  /*! \brief The number of samples until the next timeout event */
176 
177  /*! Buffer for HDLC and non-ECM data going to the T.38 channel */
179  /*! Buffer for data going to an HDLC modem. */
181  /*! Buffer for data going to a non-ECM mode modem. */
183 
184  /*! \brief A pointer to a callback routine to be called when frames are
185  exchanged. */
187  /*! \brief An opaque pointer supplied in real time frame callbacks. */
190 
191 /*!
192  T.38 gateway state.
193 */
195 {
196  /*! T.38 side state */
198  /*! Audio side state */
200  /*! T.38 core state */
202 
203  /*! \brief Error and flow logging control */
205 };
206 
207 #endif
208 /*- End of file ------------------------------------------------------------*/