1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * private/v22bis.h - ITU V.22bis modem
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2004 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 #if !defined(_SPANDSP_PRIVATE_V22BIS_H_)
27 #define _SPANDSP_PRIVATE_V22BIS_H_
28 
29 /*! The length of the equalizer buffer */
30 #define V22BIS_EQUALIZER_LEN        17
31 /*! Samples before the target position in the equalizer buffer */
32 #define V22BIS_EQUALIZER_PRE_LEN    8
33 
34 /*! The number of taps in the transmit pulse shaping filter */
35 #define V22BIS_TX_FILTER_STEPS      9
36 
37 /*! The number of taps in the receive pulse shaping/bandpass filter */
38 #define V22BIS_RX_FILTER_STEPS      27
39 
40 /*! Segments of the training sequence on the receive side */
41 enum
42 {
43     V22BIS_RX_TRAINING_STAGE_NORMAL_OPERATION,
44     V22BIS_RX_TRAINING_STAGE_SYMBOL_ACQUISITION,
45     V22BIS_RX_TRAINING_STAGE_LOG_PHASE,
46     V22BIS_RX_TRAINING_STAGE_UNSCRAMBLED_ONES,
47     V22BIS_RX_TRAINING_STAGE_UNSCRAMBLED_ONES_SUSTAINING,
48     V22BIS_RX_TRAINING_STAGE_SCRAMBLED_ONES_AT_1200,
49     V22BIS_RX_TRAINING_STAGE_SCRAMBLED_ONES_AT_1200_SUSTAINING,
50     V22BIS_RX_TRAINING_STAGE_WAIT_FOR_SCRAMBLED_ONES_AT_2400,
51     V22BIS_RX_TRAINING_STAGE_PARKED
52 };
53 
54 /*! Segments of the training sequence on the transmit side */
55 enum
56 {
57     V22BIS_TX_TRAINING_STAGE_NORMAL_OPERATION = 0,
58     V22BIS_TX_TRAINING_STAGE_INITIAL_TIMED_SILENCE,
59     V22BIS_TX_TRAINING_STAGE_INITIAL_SILENCE,
60     V22BIS_TX_TRAINING_STAGE_U11,
61     V22BIS_TX_TRAINING_STAGE_U0011,
62     V22BIS_TX_TRAINING_STAGE_S11,
63     V22BIS_TX_TRAINING_STAGE_TIMED_S11,
64     V22BIS_TX_TRAINING_STAGE_S1111,
65     V22BIS_TX_TRAINING_STAGE_PARKED
66 };
67 
68 #if defined(SPANDSP_USE_FIXED_POINT)
69 extern const complexi16_t v22bis_constellation[16];
70 #else
71 extern const complexf_t v22bis_constellation[16];
72 #endif
73 
74 /*!
75     V.22bis modem descriptor. This defines the working state for a single instance
76     of a V.22bis modem.
77 */
78 struct v22bis_state_s
79 {
80     /*! \brief The maximum permitted bit rate of the modem. Valid values are 1200 and 2400. */
81     int bit_rate;
82     /*! \brief True is this is the calling side modem. */
83     bool calling_party;
84     /*! \brief The callback function used to get the next bit to be transmitted. */
85     get_bit_func_t get_bit;
86     /*! \brief A user specified opaque pointer passed to the get_bit callback routine. */
87     void *get_bit_user_data;
88     /*! \brief The callback function used to put each bit received. */
89     put_bit_func_t put_bit;
90     /*! \brief A user specified opaque pointer passed to the put_bit callback routine. */
91     void *put_bit_user_data;
92     /*! \brief The callback function used to report modem status changes. */
93     modem_status_func_t status_handler;
94     /*! \brief A user specified opaque pointer passed to the status function. */
95     void *status_user_data;
96 
97     int negotiated_bit_rate;
98 
99     /* Receive section */
100     struct
101     {
102         /*! \brief Current offset into the RRC pulse shaping filter buffer. */
103         int rrc_filter_step;
104 
105         /*! \brief The register for the data scrambler. */
106         uint32_t scramble_reg;
107         /*! \brief A counter for the number of consecutive bits of repeating pattern through
108                    the scrambler. */
109         int scrambler_pattern_count;
110 
111         /*! \brief 0 if receiving user data. A training stage value during training */
112         int training;
113         /*! \brief A count of how far through the current training step we are. */
114         int training_count;
115 
116         /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.22bis signal. */
117         int signal_present;
118 
119         /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
120         uint32_t carrier_phase;
121         /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
122         int32_t carrier_phase_rate;
123 
124         /*! \brief A callback function which may be enabled to report every symbol's
125                    constellation position. */
126         qam_report_handler_t qam_report;
127         /*! \brief A user specified opaque pointer passed to the qam_report callback
128                    routine. */
129         void *qam_user_data;
130 
131         /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */
132         power_meter_t rx_power;
133         /*! \brief The power meter level at which carrier on is declared. */
134         int32_t carrier_on_power;
135         /*! \brief The power meter level at which carrier off is declared. */
136         int32_t carrier_off_power;
137 
138         int constellation_state;
139 
140 #if defined(SPANDSP_USE_FIXED_POINT)
141         /*! \brief The scaling factor assessed by the AGC algorithm. */
142         int16_t agc_scaling;
143         /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
144         int16_t rrc_filter[V22BIS_RX_FILTER_STEPS];
145 
146         /*! \brief The current delta factor for updating the equalizer coefficients. */
147         int16_t eq_delta;
148         /*! \brief The adaptive equalizer coefficients. */
149         complexi16_t eq_coeff[V22BIS_EQUALIZER_LEN];
150         /*! \brief The equalizer signal buffer. */
151         complexi16_t eq_buf[V22BIS_EQUALIZER_LEN];
152 
153         /*! \brief A measure of how much mismatch there is between the real constellation,
154                    and the decoded symbol positions. */
155         int32_t training_error;
156         /*! \brief The proportional part of the carrier tracking filter. */
157         int32_t carrier_track_p;
158         /*! \brief The integral part of the carrier tracking filter. */
159         int32_t carrier_track_i;
160 #else
161         /*! \brief The scaling factor assessed by the AGC algorithm. */
162         float agc_scaling;
163         /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
164         float rrc_filter[V22BIS_RX_FILTER_STEPS];
165 
166         /*! \brief The current delta factor for updating the equalizer coefficients. */
167         float eq_delta;
168         /*! \brief The adaptive equalizer coefficients. */
169         complexf_t eq_coeff[V22BIS_EQUALIZER_LEN];
170         /*! \brief The equalizer signal buffer. */
171         complexf_t eq_buf[V22BIS_EQUALIZER_LEN];
172 
173         /*! \brief A measure of how much mismatch there is between the real constellation,
174                    and the decoded symbol positions. */
175         float training_error;
176         /*! \brief The proportional part of the carrier tracking filter. */
177         float carrier_track_p;
178         /*! \brief The integral part of the carrier tracking filter. */
179         float carrier_track_i;
180 #endif
181         /*! \brief Current offset into the equalizer buffer. */
182         int eq_step;
183         /*! \brief Current write offset into the equalizer buffer. */
184         int eq_put_step;
185 
186         /*! \brief Integration variable for damping the Gardner algorithm tests. */
187         int gardner_integrate;
188         /*! \brief Current step size of Gardner algorithm integration. */
189         int gardner_step;
190         /*! \brief The total symbol timing correction since the carrier came up.
191                    This is only for performance analysis purposes. */
192         int total_baud_timing_correction;
193         /*! \brief The current fractional phase of the baud timing. */
194         int baud_phase;
195 
196         int sixteen_way_decisions;
197 
198         int pattern_repeats;
199         int last_raw_bits;
200     } rx;
201 
202     /* Transmit section */
203     struct
204     {
205 #if defined(SPANDSP_USE_FIXED_POINT)
206         /*! \brief The guard tone level. */
207         int16_t guard_tone_gain;
208         /*! \brief The gain factor needed to achieve the specified output power. */
209         int16_t gain;
210         /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
211         int16_t rrc_filter_re[V22BIS_TX_FILTER_STEPS];
212         int16_t rrc_filter_im[V22BIS_TX_FILTER_STEPS];
213 #else
214         /*! \brief The guard tone level. */
215         float guard_tone_gain;
216         /*! \brief The gain factor needed to achieve the specified output power. */
217         float gain;
218         /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
219         float rrc_filter_re[V22BIS_TX_FILTER_STEPS];
220         float rrc_filter_im[V22BIS_TX_FILTER_STEPS];
221 #endif
222 
223         /*! \brief Current offset into the RRC pulse shaping filter buffer. */
224         int rrc_filter_step;
225 
226         /*! \brief The register for the data scrambler. */
227         uint32_t scramble_reg;
228         /*! \brief A counter for the number of consecutive bits of repeating pattern through
229                    the scrambler. */
230         int scrambler_pattern_count;
231 
232         /*! \brief 0 if transmitting user data. A training stage value during training */
233         int training;
234         /*! \brief A counter used to track progress through sending the training sequence. */
235         int training_count;
236         /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
237         uint32_t carrier_phase;
238         /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
239         int32_t carrier_phase_rate;
240         /*! \brief The current phase of the guard tone (i.e. the DDS parameter). */
241         uint32_t guard_phase;
242         /*! \brief The update rate for the phase of the guard tone (i.e. the DDS increment). */
243         int32_t guard_phase_rate;
244         /*! \brief The current fractional phase of the baud timing. */
245         int baud_phase;
246         /*! \brief The code number for the current position in the constellation. */
247         int constellation_state;
248         /*! \brief An indicator to mark that we are tidying up to stop transmission. */
249         int shutdown;
250         /*! \brief The get_bit function in use at any instant. */
251         get_bit_func_t current_get_bit;
252     } tx;
253 
254     /*! \brief Error and flow logging control */
255     logging_state_t logging;
256 };
257 
258 #if defined(__cplusplus)
259 extern "C"
260 {
261 #endif
262 
263 /*! Reinitialise an existing V.22bis modem receive context.
264     \brief Reinitialise an existing V.22bis modem receive context.
265     \param s The modem context.
266     \return 0 for OK, -1 for bad parameter */
267 int v22bis_rx_restart(v22bis_state_t *s);
268 
269 void v22bis_report_status_change(v22bis_state_t *s, int status);
270 
271 void v22bis_equalizer_coefficient_reset(v22bis_state_t *s);
272 
273 #if defined(__cplusplus)
274 }
275 #endif
276 
277 #endif
278 /*- End of file ------------------------------------------------------------*/
279