v18.h

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00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * v18.h - V.18 text telephony for the deaf.
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2004-2009 Steve Underwood
00009  *
00010  * All rights reserved.
00011  *
00012  * This program is free software; you can redistribute it and/or modify
00013  * it under the terms of the GNU Lesser General Public License version 2.1,
00014  * as published by the Free Software Foundation.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  *
00025  * $Id: v18.h,v 1.3 2009/04/12 09:12:11 steveu Exp $
00026  */
00027  
00028 /*! \file */
00029 
00030 /*! \page v18_page The V.18 text telephony protocols
00031 \section v18_page_sec_1 What does it do?
00032 
00033 \section v18_page_sec_2 How does it work?
00034 */
00035 
00036 #if !defined(_SPANDSP_V18_H_)
00037 #define _SPANDSP_V18_H_
00038 
00039 typedef struct v18_state_s v18_state_t;
00040 
00041 enum
00042 {
00043     V18_MODE_NONE = 0,
00044     /* V.18 Annex A - Weitbrecht TDD at 45.45bps, half-duplex, 5 bit baudot. */
00045     V18_MODE_5BIT_45 = 1,
00046     /* V.18 Annex A - Weitbrecht TDD at 50bps, half-duplex, 5 bit baudot. */
00047     V18_MODE_5BIT_50 = 2,
00048     /* V.18 Annex B - DTMF encoding of ASCII. */
00049     V18_MODE_DTMF = 3,
00050     /* V.18 Annex C - EDT 110bps, V.21, half-duplex, ASCII. */
00051     V18_MODE_EDT = 4,
00052     /* V.18 Annex D - 300bps, Bell 103, duplex, ASCII. */
00053     V18_MODE_BELL103 = 5,
00054     /* V.18 Annex E - 1200bps Videotex terminals, ASCII. */
00055     V18_MODE_V23VIDEOTEX = 6,
00056     /* V.18 Annex F - V.21 text telephone, V.21, duplex, ASCII. */
00057     V18_MODE_V21TEXTPHONE = 7,
00058     /* V.18 Annex G - V.18 text telephone mode. */
00059     V18_MODE_V18TEXTPHONE = 8
00060 };
00061 
00062 #if defined(__cplusplus)
00063 extern "C"
00064 {
00065 #endif
00066 
00067 SPAN_DECLARE(logging_state_t *) v18_get_logging_state(v18_state_t *s);
00068 
00069 /*! Initialise a V.18 context.
00070     \brief Initialise a V.18 context.
00071     \param s The V.18 context.
00072     \param caller TRUE if caller mode, else answerer mode.
00073     \param mode Mode of operation.
00074     \param put_msg A callback routine called to deliver the received text
00075            to the application.
00076     \param user_data An opaque pointer for the callback routine.
00077     \return A pointer to the V.18 context, or NULL if there was a problem. */
00078 SPAN_DECLARE(v18_state_t *) v18_init(v18_state_t *s,
00079                                      int caller,
00080                                      int mode,
00081                                      put_msg_func_t put_msg,
00082                                      void *user_data);
00083 
00084 /*! Release a V.18 context.
00085     \brief Release a V.18 context.
00086     \param s The V.18 context.
00087     \return 0 for OK. */
00088 SPAN_DECLARE(int) v18_release(v18_state_t *s);
00089 
00090 /*! Free a V.18 context.
00091     \brief Release a V.18 context.
00092     \param s The V.18 context.
00093     \return 0 for OK. */
00094 SPAN_DECLARE(int) v18_free(v18_state_t *s);
00095 
00096 /*! Generate a block of V.18 audio samples.
00097     \brief Generate a block of V.18 audio samples.
00098     \param s The V.18 context.
00099     \param amp The audio sample buffer.
00100     \param max_len The number of samples to be generated.
00101     \return The number of samples actually generated.
00102 */
00103 SPAN_DECLARE(int) v18_tx(v18_state_t *s, int16_t amp[], int max_len);
00104 
00105 /*! Process a block of received V.18 audio samples.
00106     \brief Process a block of received V.18 audio samples.
00107     \param s The V.18 context.
00108     \param amp The audio sample buffer.
00109     \param len The number of samples in the buffer.
00110 */
00111 SPAN_DECLARE(int) v18_rx(v18_state_t *s, const int16_t amp[], int len);
00112 
00113 /*! \brief Put a string to a V.18 context's input buffer.
00114     \param s The V.18 context.
00115     \param msg The string to be added.
00116     \param len The length of the string. If negative, the string is
00117            assumed to be a NULL terminated string.
00118     \return The number of characters actually added. This may be less than the
00119             length of the digit string, if the buffer fills up. */
00120 SPAN_DECLARE(int) v18_put(v18_state_t *s, const char msg[], int len);
00121 
00122 /*! Convert a text string to a V.18 DTMF string.
00123     \brief Convert a text string to a V.18 DTMF string.
00124     \param s The V.18 context.
00125     \param dtmf The resulting DTMF string.
00126     \param msg The text string to be converted.
00127     \return The length of the DTMF string.
00128 */
00129 SPAN_DECLARE(int) v18_encode_dtmf(v18_state_t *s, char dtmf[], const char msg[]);
00130 
00131 /*! Convert a V.18 DTMF string to a text string.
00132     \brief Convert a V.18 DTMF string to a text string.
00133     \param s The V.18 context.
00134     \param msg The resulting test string.
00135     \param dtmf The DTMF string to be converted.
00136     \return The length of the text string.
00137 */
00138 SPAN_DECLARE(int) v18_decode_dtmf(v18_state_t *s, char msg[], const char dtmf[]);
00139 
00140 SPAN_DECLARE(uint16_t) v18_encode_baudot(v18_state_t *s, uint8_t ch);
00141 
00142 SPAN_DECLARE(uint8_t) v18_decode_baudot(v18_state_t *s, uint8_t ch);
00143 
00144 /*! \brief Return a short name for an V.18 mode
00145     \param mode The code for the V.18 mode.
00146     \return A pointer to the name.
00147 */
00148 SPAN_DECLARE(const char *) v18_mode_to_str(int mode);
00149 
00150 #if defined(__cplusplus)
00151 }
00152 #endif
00153 
00154 #endif
00155 /*- End of file ------------------------------------------------------------*/

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