retronetworking
/
freeswitch
13
0
Fork 0
Code Pull Requests Releases Activity
freeswitch/libs/spandsp/src/v27ter_tx.c

453 lines
16 KiB
C
Raw Blame History

/*
* SpanDSP - a series of DSP components for telephony
*
* v27ter_tx.c - ITU V.27ter 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.
*/
/*! \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/vector_int.h"
#include "spandsp/complex_vector_int.h"
#include "spandsp/async.h"
#include "spandsp/dds.h"
#include "spandsp/power_meter.h"
#include "spandsp/v27ter_tx.h"
#include "spandsp/private/logging.h"
#include "spandsp/private/v27ter_tx.h"
#if defined(SPANDSP_USE_FIXED_POINT)
#include "v27ter_tx_4800_fixed_rrc.h"
#include "v27ter_tx_2400_fixed_rrc.h"
#else
#include "v27ter_tx_4800_floating_rrc.h"
#include "v27ter_tx_2400_floating_rrc.h"
#endif
/*! The nominal frequency of the carrier, in Hertz */
#define CARRIER_NOMINAL_FREQ 1800.0f
/* Segments of the training sequence */
/* V.27ter defines a long and a short sequence. FAX doesn't use the
short sequence, so it is not implemented here. */
/*! The start of training segment 1, in symbols */
#define V27TER_TRAINING_SEG_1 0
/*! The start of training segment 2, in symbols */
#define V27TER_TRAINING_SEG_2 (V27TER_TRAINING_SEG_1 + 320)
/*! The start of training segment 3, in symbols */
#define V27TER_TRAINING_SEG_3 (V27TER_TRAINING_SEG_2 + 32)
/*! The start of training segment 4, in symbols */
#define V27TER_TRAINING_SEG_4 (V27TER_TRAINING_SEG_3 + 50)
/*! The start of training segment 5, in symbols */
#define V27TER_TRAINING_SEG_5 (V27TER_TRAINING_SEG_4 + 1074)
/*! The end of the training, in symbols */
#define V27TER_TRAINING_END (V27TER_TRAINING_SEG_5 + 8)
/*! The end of the shutdown sequence, in symbols */
#define V27TER_TRAINING_SHUTDOWN_END (V27TER_TRAINING_END + 32)
static int fake_get_bit(void *user_data)
{
return 1;
}
/*- End of function --------------------------------------------------------*/
static __inline__ int scramble(v27ter_tx_state_t *s, int in_bit)
{
int out_bit;
/* This scrambler is really quite messy to implement. There seems to be no efficient shortcut */
out_bit = (in_bit ^ (s->scramble_reg >> 5) ^ (s->scramble_reg >> 6)) & 1;
if (s->scrambler_pattern_count >= 33)
{
out_bit ^= 1;
s->scrambler_pattern_count = 0;
}
else
{
if ((((s->scramble_reg >> 7) ^ out_bit) & ((s->scramble_reg >> 8) ^ out_bit) & ((s->scramble_reg >> 11) ^ out_bit) & 1))
s->scrambler_pattern_count = 0;
else
s->scrambler_pattern_count++;
}
s->scramble_reg = (s->scramble_reg << 1) | out_bit;
return out_bit;
}
/*- End of function --------------------------------------------------------*/
static __inline__ int get_scrambled_bit(v27ter_tx_state_t *s)
{
int 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;
}
return scramble(s, bit);
}
/*- End of function --------------------------------------------------------*/
#if defined(SPANDSP_USE_FIXED_POINT)
static complexi16_t getbaud(v27ter_tx_state_t *s)
#else
static complexf_t getbaud(v27ter_tx_state_t *s)
#endif
{
static const int phase_steps_4800[8] =
{
1, 0, 2, 3, 6, 7, 5, 4
};
static const int phase_steps_2400[4] =
{
0, 2, 6, 4
};
#if defined(SPANDSP_USE_FIXED_POINT)
static const complexi16_t constellation[8] =
{
{ 1414, 0000}, /* 0deg */
{ 1000, 1000}, /* 45deg */
{ 0000, 1414}, /* 90deg */
{-1000, 1000}, /* 135deg */
{-1414, 0000}, /* 180deg */
{-1000, -1000}, /* 225deg */
{ 0000, -1414}, /* 270deg */
{ 1000, -1000} /* 315deg */
};
static const complexi16_t zero = {0, 0};
#else
static const complexf_t constellation[8] =
{
{ 1.414f, 0.0f}, /* 0deg */
{ 1.0f, 1.0f}, /* 45deg */
{ 0.0f, 1.414f}, /* 90deg */
{-1.0f, 1.0f}, /* 135deg */
{-1.414f, 0.0f}, /* 180deg */
{-1.0f, -1.0f}, /* 225deg */
{ 0.0f, -1.414f}, /* 270deg */
{ 1.0f, -1.0f} /* 315deg */
};
static const complexf_t zero = {0.0f, 0.0f};
#endif
int bits;
if (s->in_training)
{
/* Send the training sequence */
if (++s->training_step <= V27TER_TRAINING_SEG_5)
{
if (s->training_step <= V27TER_TRAINING_SEG_4)
{
if (s->training_step <= V27TER_TRAINING_SEG_2)
{
/* Segment 1: Unmodulated carrier (talker echo protection) */
return constellation[0];
}
if (s->training_step <= V27TER_TRAINING_SEG_3)
{
/* Segment 2: Silence */
return zero;
}
/* Segment 3: Regular reversals... */
s->constellation_state = (s->constellation_state + 4) & 7;
return constellation[s->constellation_state];
}
/* Segment 4: Scrambled reversals... */
/* Apply the 1 + x^-6 + x^-7 scrambler. We want every third
bit from the scrambler. */
bits = get_scrambled_bit(s) << 2;
get_scrambled_bit(s);
get_scrambled_bit(s);
s->constellation_state = (s->constellation_state + bits) & 7;
return constellation[s->constellation_state];
}
/* 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.27ter. Just
send some ones, to ensure we get the real data bits through, even
with bad ISI. */
if (s->training_step == V27TER_TRAINING_END + 1)
{
/* End of the last segment - segment 5: All ones */
/* 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 == V27TER_TRAINING_SHUTDOWN_END)
{
if (s->status_handler)
s->status_handler(s->status_user_data, SIG_STATUS_SHUTDOWN_COMPLETE);
}
}
/* 4800bps uses 8 phases. 2400bps uses 4 phases. */
if (s->bit_rate == 4800)
{
bits = get_scrambled_bit(s);
bits = (bits << 1) | get_scrambled_bit(s);
bits = (bits << 1) | get_scrambled_bit(s);
bits = phase_steps_4800[bits];
}
else
{
bits = get_scrambled_bit(s);
bits = (bits << 1) | get_scrambled_bit(s);
bits = phase_steps_2400[bits];
}
s->constellation_state = (s->constellation_state + bits) & 7;
return constellation[s->constellation_state];
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE_NONSTD(int) v27ter_tx(v27ter_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 >= V27TER_TRAINING_SHUTDOWN_END)
{
/* Once we have sent the shutdown symbols, we stop sending completely. */
return 0;
}
/* The symbol rates for the two bit rates are different. This makes it difficult to
merge both generation procedures into a single efficient loop. We do not bother
trying. We use two independent loops, filter coefficients, etc. */
if (s->bit_rate == 4800)
{
for (sample = 0; sample < len; sample++)
{
if (++s->baud_phase >= 5)
{
s->baud_phase -= 5;
s->rrc_filter[s->rrc_filter_step] =
s->rrc_filter[s->rrc_filter_step + V27TER_TX_FILTER_STEPS] = getbaud(s);
if (++s->rrc_filter_step >= V27TER_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 < V27TER_TX_FILTER_STEPS; i++)
{
x.re += (int32_t) tx_pulseshaper_4800[TX_PULSESHAPER_4800_COEFF_SETS - 1 - s->baud_phase][i]*(int32_t) s->rrc_filter[i + s->rrc_filter_step].re;
x.im += (int32_t) tx_pulseshaper_4800[TX_PULSESHAPER_4800_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 >>= 14;
x.im >>= 14;
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_4800) >> 15);
#else
x = complex_setf(0.0f, 0.0f);
for (i = 0; i < V27TER_TX_FILTER_STEPS; i++)
{
x.re += tx_pulseshaper_4800[TX_PULSESHAPER_4800_COEFF_SETS - 1 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].re;
x.im += tx_pulseshaper_4800[TX_PULSESHAPER_4800_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_4800);
#endif
}
}
else
{
for (sample = 0; sample < len; sample++)
{
if ((s->baud_phase += 3) >= 20)
{
s->baud_phase -= 20;
s->rrc_filter[s->rrc_filter_step] =
s->rrc_filter[s->rrc_filter_step + V27TER_TX_FILTER_STEPS] = getbaud(s);
if (++s->rrc_filter_step >= V27TER_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 < V27TER_TX_FILTER_STEPS; i++)
{
x.re += (int32_t) tx_pulseshaper_2400[TX_PULSESHAPER_2400_COEFF_SETS - 1 - s->baud_phase][i]*(int32_t) s->rrc_filter[i + s->rrc_filter_step].re;
x.im += (int32_t) tx_pulseshaper_2400[TX_PULSESHAPER_2400_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 >>= 14;
x.im >>= 14;
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_2400) >> 15);
#else
x = complex_setf(0.0f, 0.0f);
for (i = 0; i < V27TER_TX_FILTER_STEPS; i++)
{
x.re += tx_pulseshaper_2400[TX_PULSESHAPER_2400_COEFF_SETS - 1 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].re;
x.im += tx_pulseshaper_2400[TX_PULSESHAPER_2400_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_2400);
#endif
}
}
return sample;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v27ter_tx_power(v27ter_tx_state_t *s, float power)
{
float l;
l = powf(10.0f, (power - DBM0_MAX_POWER)/20.0f)*32768.0f;
#if defined(SPANDSP_USE_FIXED_POINT)
s->gain_2400 = 16.0f*1.024f*(32767.0f/28828.51f)*l/TX_PULSESHAPER_2400_GAIN;
s->gain_4800 = 16.0f*1.024f*(32767.0f/28828.46f)*l/TX_PULSESHAPER_4800_GAIN;
#else
s->gain_2400 = l/TX_PULSESHAPER_2400_GAIN;
s->gain_4800 = l/TX_PULSESHAPER_4800_GAIN;
#endif
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) v27ter_tx_set_get_bit(v27ter_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) v27ter_tx_set_modem_status_handler(v27ter_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 *) v27ter_tx_get_logging_state(v27ter_tx_state_t *s)
{
return &s->logging;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v27ter_tx_restart(v27ter_tx_state_t *s, int bit_rate, int tep)
{
if (bit_rate != 4800 && bit_rate != 2400)
return -1;
s->bit_rate = bit_rate;
#if defined(SPANDSP_USE_FIXED_POINT)
cvec_zeroi16(s->rrc_filter, sizeof(s->rrc_filter)/sizeof(s->rrc_filter[0]));
#else
cvec_zerof(s->rrc_filter, sizeof(s->rrc_filter)/sizeof(s->rrc_filter[0]));
#endif
s->rrc_filter_step = 0;
s->scramble_reg = 0x3C;
s->scrambler_pattern_count = 0;
s->in_training = TRUE;
s->training_step = (tep) ? V27TER_TRAINING_SEG_1 : V27TER_TRAINING_SEG_2;
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(v27ter_tx_state_t *) v27ter_tx_init(v27ter_tx_state_t *s, int bit_rate, int tep, get_bit_func_t get_bit, void *user_data)
{
switch (bit_rate)
{
case 4800:
case 2400:
break;
default:
return NULL;
}
if (s == NULL)
{
if ((s = (v27ter_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.27ter TX");
s->get_bit = get_bit;
s->get_bit_user_data = user_data;
s->carrier_phase_rate = dds_phase_ratef(CARRIER_NOMINAL_FREQ);
v27ter_tx_power(s, -14.0f);
v27ter_tx_restart(s, bit_rate, tep);
return s;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v27ter_tx_release(v27ter_tx_state_t *s)
{
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) v27ter_tx_free(v27ter_tx_state_t *s)
{
free(s);
return 0;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/
View Git Blame Copy Permalink