spandsp  0.0.6
v18.h
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1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * v18.h - V.18 text telephony for the deaf.
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2004-2009 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 /*! \page v18_page The V.18 text telephony protocols
29 \section v18_page_sec_1 What does it do?
30 
31 \section v18_page_sec_2 How does it work?
32 */
33 
34 #if !defined(_SPANDSP_V18_H_)
35 #define _SPANDSP_V18_H_
36 
37 typedef struct v18_state_s v18_state_t;
38 
39 enum
40 {
41  V18_MODE_NONE = 0,
42  /* V.18 Annex A - Weitbrecht TDD at 45.45bps, half-duplex, 5 bit baudot. */
43  V18_MODE_5BIT_45 = 1,
44  /* V.18 Annex A - Weitbrecht TDD at 50bps, half-duplex, 5 bit baudot. */
45  V18_MODE_5BIT_50 = 2,
46  /* V.18 Annex B - DTMF encoding of ASCII. */
47  V18_MODE_DTMF = 3,
48  /* V.18 Annex C - EDT 110bps, V.21, half-duplex, ASCII. */
49  V18_MODE_EDT = 4,
50  /* V.18 Annex D - 300bps, Bell 103, duplex, ASCII. */
51  V18_MODE_BELL103 = 5,
52  /* V.18 Annex E - 1200bps Videotex terminals, ASCII. */
53  V18_MODE_V23VIDEOTEX = 6,
54  /* V.18 Annex F - V.21 text telephone, V.21, duplex, ASCII. */
55  V18_MODE_V21TEXTPHONE = 7,
56  /* V.18 Annex G - V.18 text telephone mode. */
57  V18_MODE_V18TEXTPHONE = 8
58 };
59 
60 #if defined(__cplusplus)
61 extern "C"
62 {
63 #endif
64 
65 SPAN_DECLARE(logging_state_t *) v18_get_logging_state(v18_state_t *s);
66 
67 /*! Initialise a V.18 context.
68  \brief Initialise a V.18 context.
69  \param s The V.18 context.
70  \param calling_party TRUE if caller mode, else answerer mode.
71  \param mode Mode of operation.
72  \param put_msg A callback routine called to deliver the received text
73  to the application.
74  \param user_data An opaque pointer for the callback routine.
75  \return A pointer to the V.18 context, or NULL if there was a problem. */
76 SPAN_DECLARE(v18_state_t *) v18_init(v18_state_t *s,
77  int calling_party,
78  int mode,
79  put_msg_func_t put_msg,
80  void *user_data);
81 
82 /*! Release a V.18 context.
83  \brief Release a V.18 context.
84  \param s The V.18 context.
85  \return 0 for OK. */
86 SPAN_DECLARE(int) v18_release(v18_state_t *s);
87 
88 /*! Free a V.18 context.
89  \brief Release a V.18 context.
90  \param s The V.18 context.
91  \return 0 for OK. */
92 SPAN_DECLARE(int) v18_free(v18_state_t *s);
93 
94 /*! Generate a block of V.18 audio samples.
95  \brief Generate a block of V.18 audio samples.
96  \param s The V.18 context.
97  \param amp The audio sample buffer.
98  \param max_len The number of samples to be generated.
99  \return The number of samples actually generated.
100 */
101 SPAN_DECLARE_NONSTD(int) v18_tx(v18_state_t *s, int16_t amp[], int max_len);
102 
103 /*! Process a block of received V.18 audio samples.
104  \brief Process a block of received V.18 audio samples.
105  \param s The V.18 context.
106  \param amp The audio sample buffer.
107  \param len The number of samples in the buffer.
108 */
109 SPAN_DECLARE_NONSTD(int) v18_rx(v18_state_t *s, const int16_t amp[], int len);
110 
111 /*! \brief Put a string to a V.18 context's input buffer.
112  \param s The V.18 context.
113  \param msg The string to be added.
114  \param len The length of the string. If negative, the string is
115  assumed to be a NULL terminated string.
116  \return The number of characters actually added. This may be less than the
117  length of the digit string, if the buffer fills up. If the string is
118  invalid, this function will return -1. */
119 SPAN_DECLARE(int) v18_put(v18_state_t *s, const char msg[], int len);
120 
121 /*! Convert a text string to a V.18 DTMF string.
122  \brief Convert a text string to a V.18 DTMF string.
123  \param s The V.18 context.
124  \param dtmf The resulting DTMF string.
125  \param msg The text string to be converted.
126  \return The length of the DTMF string.
127 */
128 SPAN_DECLARE(int) v18_encode_dtmf(v18_state_t *s, char dtmf[], const char msg[]);
129 
130 /*! Convert a V.18 DTMF string to a text string.
131  \brief Convert a V.18 DTMF string to a text string.
132  \param s The V.18 context.
133  \param msg The resulting test string.
134  \param dtmf The DTMF string to be converted.
135  \return The length of the text string.
136 */
137 SPAN_DECLARE(int) v18_decode_dtmf(v18_state_t *s, char msg[], const char dtmf[]);
138 
139 SPAN_DECLARE(uint16_t) v18_encode_baudot(v18_state_t *s, uint8_t ch);
140 
141 SPAN_DECLARE(uint8_t) v18_decode_baudot(v18_state_t *s, uint8_t ch);
142 
143 /*! \brief Return a short name for an V.18 mode
144  \param mode The code for the V.18 mode.
145  \return A pointer to the name.
146 */
147 SPAN_DECLARE(const char *) v18_mode_to_str(int mode);
148 
149 #if defined(__cplusplus)
150 }
151 #endif
152 
153 #endif
154 /*- End of file ------------------------------------------------------------*/
void(* put_msg_func_t)(void *user_data, const uint8_t *msg, int len)
Definition: async.h:93
int calling_party
TRUE if we are the calling modem.
Definition: private/v18.h:32
int v18_decode_dtmf(v18_state_t *s, char msg[], const char dtmf[])
Convert a V.18 DTMF string to a text string.
Definition: v18.c:408
int v18_encode_dtmf(v18_state_t *s, char dtmf[], const char msg[])
Convert a text string to a V.18 DTMF string.
Definition: v18.c:387
v18_state_t * v18_init(v18_state_t *s, int calling_party, int mode, put_msg_func_t put_msg, void *user_data)
Initialise a V.18 context.
Definition: v18.c:826
SPAN_DECLARE_NONSTD(int) v18_tx(v18_state_t *s
Generate a block of V.18 audio samples.
int v18_release(v18_state_t *s)
Release a V.18 context.
Definition: v18.c:902
Definition: private/logging.h:33
int v18_put(v18_state_t *s, const char msg[], int len)
Put a string to a V.18 context&#39;s input buffer.
Definition: v18.c:779
int v18_free(v18_state_t *s)
Release a V.18 context.
Definition: v18.c:908
const char * v18_mode_to_str(int mode)
Return a short name for an V.18 mode.
Definition: v18.c:915
Definition: private/v18.h:29