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freeswitch/libs/spandsp/src/v29tx.c

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/*
* SpanDSP - a series of DSP components for telephony
*
* v29tx.c - ITU V.29 modem transmit part
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2003 Steve Underwood
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id: v29tx.c,v 1.89 2009/06/02 16:03:56 steveu Exp $
*/
/*! \file */
#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif
#include <stdio.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#if defined(HAVE_TGMATH_H)
#include <tgmath.h>
#endif
#if defined(HAVE_MATH_H)
#include <math.h>
#endif
#include "floating_fudge.h"
#include "spandsp/telephony.h"
#include "spandsp/fast_convert.h"
#include "spandsp/logging.h"
#include "spandsp/complex.h"
#include "spandsp/vector_float.h"
#include "spandsp/complex_vector_float.h"
#include "spandsp/async.h"
#include "spandsp/dds.h"
#include "spandsp/power_meter.h"
#include "spandsp/v29tx.h"
#include "spandsp/private/logging.h"
#include "spandsp/private/v29tx.h"
#include "v29tx_constellation_maps.h"
#if defined(SPANDSP_USE_FIXED_POINT)
#include "v29tx_fixed_rrc.h"
#else
#include "v29tx_floating_rrc.h"
#endif
/*! The nominal frequency of the carrier, in Hertz */
#define CARRIER_NOMINAL_FREQ 1700.0f
/* Segments of the training sequence */
/*! The start of the optional TEP, that may preceed the actual training, in symbols */
#define V29_TRAINING_SEG_TEP 0
/*! The start of training segment 1, in symbols */
#define V29_TRAINING_SEG_1 (V29_TRAINING_SEG_TEP + 480)
/*! The start of training segment 2, in symbols */
#define V29_TRAINING_SEG_2 (V29_TRAINING_SEG_1 + 48)
/*! The start of training segment 3, in symbols */
#define V29_TRAINING_SEG_3 (V29_TRAINING_SEG_2 + 128)
/*! The start of training segment 4, in symbols */
#define V29_TRAINING_SEG_4 (V29_TRAINING_SEG_3 + 384)
/*! The end of the training, in symbols */
#define V29_TRAINING_END (V29_TRAINING_SEG_4 + 48)
/*! The end of the shutdown sequence, in symbols */
#define V29_TRAINING_SHUTDOWN_END (V29_TRAINING_END + 32)
static int fake_get_bit(void *user_data)
{
return 1;
}
/*- End of function --------------------------------------------------------*/
static __inline__ int get_scrambled_bit(v29_tx_state_t *s)
{
int bit;
int out_bit;
if ((bit = s->current_get_bit(s->get_bit_user_data)) == SIG_STATUS_END_OF_DATA)
{
/* End of real data. Switch to the fake get_bit routine, until we
have shut down completely. */
if (s->status_handler)
s->status_handler(s->status_user_data, SIG_STATUS_END_OF_DATA);
s->current_get_bit = fake_get_bit;
s->in_training = TRUE;
bit = 1;
}
out_bit = (bit ^ (s->scramble_reg >> 17) ^ (s->scramble_reg >> 22)) & 1;
s->scramble_reg = (s->scramble_reg << 1) | out_bit;
return out_bit;
}
/*- End of function --------------------------------------------------------*/
#if defined(SPANDSP_USE_FIXED_POINT)
static __inline__ complexi16_t getbaud(v29_tx_state_t *s)
#else
static __inline__ complexf_t getbaud(v29_tx_state_t *s)
#endif
{
static const int phase_steps_9600[8] =
{
1, 0, 2, 3, 6, 7, 5, 4
};
static const int phase_steps_4800[4] =
{
0, 2, 6, 4
};
#if defined(SPANDSP_USE_FIXED_POINT)
static const complexi16_t zero = {0, 0};
#else
static const complexf_t zero = {0.0f, 0.0f};
#endif
int bits;
int amp;
int bit;
if (s->in_training)
{
/* Send the training sequence */
if (++s->training_step <= V29_TRAINING_SEG_4)
{
if (s->training_step <= V29_TRAINING_SEG_3)
{
if (s->training_step <= V29_TRAINING_SEG_1)
{
/* Optional segment: Unmodulated carrier (talker echo protection) */
return v29_9600_constellation[0];
}
if (s->training_step <= V29_TRAINING_SEG_2)
{
/* Segment 1: silence */
return zero;
}
/* Segment 2: ABAB... */
return v29_abab_constellation[(s->training_step & 1) + s->training_offset];
}
/* Segment 3: CDCD... */
/* Apply the 1 + x^-6 + x^-7 training scrambler */
bit = s->training_scramble_reg & 1;
s->training_scramble_reg >>= 1;
s->training_scramble_reg |= (((bit ^ s->training_scramble_reg) & 1) << 6);
return v29_cdcd_constellation[bit + s->training_offset];
}
/* We should be in the block of test ones, or shutdown ones, if we get here. */
/* There is no graceful shutdown procedure defined for V.29. Just
send some ones, to ensure we get the real data bits through, even
with bad ISI. */
if (s->training_step == V29_TRAINING_END + 1)
{
/* Switch from the fake get_bit routine, to the user supplied real
one, and we are up and running. */
s->current_get_bit = s->get_bit;
s->in_training = FALSE;
}
if (s->training_step == V29_TRAINING_SHUTDOWN_END)
{
if (s->status_handler)
s->status_handler(s->status_user_data, SIG_STATUS_SHUTDOWN_COMPLETE);
}
}
/* 9600bps uses the full constellation.
7200bps uses only the first half of the full constellation.
4800bps uses the smaller constellation. */
amp = 0;
/* We only use an amplitude bit at 9600bps */
if (s->bit_rate == 9600 && get_scrambled_bit(s))
amp = 8;
/*endif*/
bits = get_scrambled_bit(s);
bits = (bits << 1) | get_scrambled_bit(s);
if (s->bit_rate == 4800)
{
bits = phase_steps_4800[bits];
}
else
{
bits = (bits << 1) | get_scrambled_bit(s);
bits = phase_steps_9600[bits];
}
s->constellation_state = (s->constellation_state + bits) & 7;
return v29_9600_constellation[amp | s->constellation_state];
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE_NONSTD(int) v29_tx(v29_tx_state_t *s, int16_t amp[], int len)
{
#if defined(SPANDSP_USE_FIXED_POINT)
complexi_t x;
complexi_t z;
#else
complexf_t x;
complexf_t z;
#endif
int i;
int sample;
if (s->training_step >= V29_TRAINING_SHUTDOWN_END)
{
/* Once we have sent the shutdown symbols, we stop sending completely. */
return 0;
}
for (sample = 0; sample < len; sample++)
{
if ((s->baud_phase += 3) >= 10)
{
s->baud_phase -= 10;
s->rrc_filter[s->rrc_filter_step] =
s->rrc_filter[s->rrc_filter_step + V29_TX_FILTER_STEPS] = getbaud(s);
if (++s->rrc_filter_step >= V29_TX_FILTER_STEPS)
s->rrc_filter_step = 0;
}
/* Root raised cosine pulse shaping at baseband */
#if defined(SPANDSP_USE_FIXED_POINT)
x = complex_seti(0, 0);
for (i = 0; i < V29_TX_FILTER_STEPS; i++)
{
x.re += (int32_t) tx_pulseshaper[TX_PULSESHAPER_COEFF_SETS - 1 - s->baud_phase][i]*(int32_t) s->rrc_filter[i + s->rrc_filter_step].re;
x.im += (int32_t) tx_pulseshaper[TX_PULSESHAPER_COEFF_SETS - 1 - s->baud_phase][i]*(int32_t) s->rrc_filter[i + s->rrc_filter_step].im;
}
/* Now create and modulate the carrier */
x.re >>= 4;
x.im >>= 4;
z = dds_complexi(&(s->carrier_phase), s->carrier_phase_rate);
/* Don't bother saturating. We should never clip. */
i = (x.re*z.re - x.im*z.im) >> 15;
amp[sample] = (int16_t) ((i*s->gain) >> 15);
#else
x = complex_setf(0.0f, 0.0f);
for (i = 0; i < V29_TX_FILTER_STEPS; i++)
{
x.re += tx_pulseshaper[TX_PULSESHAPER_COEFF_SETS - 1 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].re;
x.im += tx_pulseshaper[TX_PULSESHAPER_COEFF_SETS - 1 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].im;
}
/* Now create and modulate the carrier */
z = dds_complexf(&(s->carrier_phase), s->carrier_phase_rate);
/* Don't bother saturating. We should never clip. */
amp[sample] = (int16_t) lfastrintf((x.re*z.re - x.im*z.im)*s->gain);
#endif
}
return sample;
}
/*- End of function --------------------------------------------------------*/
static void set_working_gain(v29_tx_state_t *s)
{
#if defined(SPANDSP_USE_FIXED_POINT)
switch (s->bit_rate)
{
case 9600:
s->gain = 0.387f*s->base_gain*16.0f*32767.0f/30672.52f;
break;
case 7200:
s->gain = 0.605f*s->base_gain*16.0f*32767.0f/30672.52f;
break;
case 4800:
s->gain = 0.470f*s->base_gain*16.0f*32767.0f/30672.52f;
break;
default:
break;
}
#else
switch (s->bit_rate)
{
case 9600:
s->gain = 0.387f*s->base_gain;
break;
case 7200:
s->gain = 0.605f*s->base_gain;
break;
case 4800:
s->gain = 0.470f*s->base_gain;
break;
default:
break;
}
#endif
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v29_tx_power(v29_tx_state_t *s, float power)
{
/* The constellation does not maintain constant average power as we change bit rates.
We need to scale the gain we get here by a bit rate specific scaling factor each
time we restart the modem. */
s->base_gain = powf(10.0f, (power - DBM0_MAX_POWER)/20.0f)*32768.0f/TX_PULSESHAPER_GAIN;
set_working_gain(s);
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v29_tx_set_get_bit(v29_tx_state_t *s, get_bit_func_t get_bit, void *user_data)
{
if (s->get_bit == s->current_get_bit)
s->current_get_bit = get_bit;
s->get_bit = get_bit;
s->get_bit_user_data = user_data;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v29_tx_set_modem_status_handler(v29_tx_state_t *s, modem_tx_status_func_t handler, void *user_data)
{
s->status_handler = handler;
s->status_user_data = user_data;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(logging_state_t *) v29_tx_get_logging_state(v29_tx_state_t *s)
{
return &s->logging;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v29_tx_restart(v29_tx_state_t *s, int bit_rate, int tep)
{
span_log(&s->logging, SPAN_LOG_FLOW, "Restarting V.29\n");
s->bit_rate = bit_rate;
set_working_gain(s);
switch (s->bit_rate)
{
case 9600:
s->training_offset = 0;
break;
case 7200:
s->training_offset = 2;
break;
case 4800:
s->training_offset = 4;
break;
default:
return -1;
}
#if defined(SPANDSP_USE_FIXED_POINT)
memset(s->rrc_filter, 0, sizeof(s->rrc_filter));
#else
cvec_zerof(s->rrc_filter, sizeof(s->rrc_filter)/sizeof(s->rrc_filter[0]));
#endif
s->rrc_filter_step = 0;
s->scramble_reg = 0;
s->training_scramble_reg = 0x2A;
s->in_training = TRUE;
s->training_step = (tep) ? V29_TRAINING_SEG_TEP : V29_TRAINING_SEG_1;
s->carrier_phase = 0;
s->baud_phase = 0;
s->constellation_state = 0;
s->current_get_bit = fake_get_bit;
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(v29_tx_state_t *) v29_tx_init(v29_tx_state_t *s, int bit_rate, int tep, get_bit_func_t get_bit, void *user_data)
{
switch (bit_rate)
{
case 9600:
case 7200:
case 4800:
break;
default:
return NULL;
}
if (s == NULL)
{
if ((s = (v29_tx_state_t *) malloc(sizeof(*s))) == NULL)
return NULL;
}
memset(s, 0, sizeof(*s));
span_log_init(&s->logging, SPAN_LOG_NONE, NULL);
span_log_set_protocol(&s->logging, "V.29 TX");
s->get_bit = get_bit;
s->get_bit_user_data = user_data;
s->carrier_phase_rate = dds_phase_ratef(CARRIER_NOMINAL_FREQ);
v29_tx_power(s, -14.0f);
v29_tx_restart(s, bit_rate, tep);
return s;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v29_tx_release(v29_tx_state_t *s)
{
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v29_tx_free(v29_tx_state_t *s)
{
free(s);
return 0;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/
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