Mercurial > hg > audiostuff
diff spandsp-0.0.3/spandsp-0.0.3/src/v27ter_tx.c @ 5:f762bf195c4b
import spandsp-0.0.3
author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
---|---|
date | Fri, 25 Jun 2010 16:00:21 +0200 |
parents | |
children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/spandsp-0.0.3/spandsp-0.0.3/src/v27ter_tx.c Fri Jun 25 16:00:21 2010 +0200 @@ -0,0 +1,624 @@ +/* + * 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 General Public License version 2, 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + * $Id: v27ter_tx.c,v 1.48 2006/11/28 16:59:57 steveu Exp $ + */ + +/*! \file */ + +#ifdef 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 "spandsp/telephony.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/v27ter_tx.h" + +#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. */ +#define V27TER_TRAINING_SEG_1 0 +#define V27TER_TRAINING_SEG_2 (V27TER_TRAINING_SEG_1 + 320) +#define V27TER_TRAINING_SEG_3 (V27TER_TRAINING_SEG_2 + 32) +#define V27TER_TRAINING_SEG_4 (V27TER_TRAINING_SEG_3 + 50) +#define V27TER_TRAINING_SEG_5 (V27TER_TRAINING_SEG_4 + 1074) +#define V27TER_TRAINING_END (V27TER_TRAINING_SEG_5 + 8) +#define V27TER_TRAINING_SHUTDOWN_END (V27TER_TRAINING_END + 32) + +/* Raised root cosine pulse shaping; Beta = 0.5; 4 symbols either + side of the centre. */ +/* Created with mkshape -r 0.025 0.5 181 -l and then split up */ +#define PULSESHAPER_2400_GAIN (19.972065748f/20.0f) +#define PULSESHAPER_2400_COEFF_SETS 20 +static const float pulseshaper_2400[PULSESHAPER_2400_COEFF_SETS][V27TER_TX_FILTER_STEPS] = +{ + { + 0.0050051219f, /* Filter 0 */ + 0.0107180844f, + -0.0150077814f, + -0.0750272071f, + 0.5786341413f, + 0.5786341413f, + -0.0750272071f, + -0.0150077814f, + 0.0107180844f + }, + { + 0.0036624469f, /* Filter 1 */ + 0.0131516633f, + -0.0107913392f, + -0.0957820135f, + 0.6671466059f, + 0.4891745311f, + -0.0541239470f, + -0.0179109014f, + 0.0079099936f + }, + { + 0.0020204744f, /* Filter 2 */ + 0.0150588729f, + -0.0053908083f, + -0.1154114754f, + 0.7528295479f, + 0.4006032722f, + -0.0339459430f, + -0.0194500407f, + 0.0048904515f + }, + { + 0.0001596234f, /* Filter 3 */ + 0.0163079778f, + 0.0009858079f, + -0.1328632049f, + 0.8338068363f, + 0.3146585634f, + -0.0152415667f, + -0.0196492903f, + 0.0018247182f + }, + { + -0.0018233575f, /* Filter 4 */ + 0.0167957238f, + 0.0080554403f, + -0.1470417557f, + 0.9082626683f, + 0.2329352195f, + 0.0013822552f, + -0.0186004475f, + -0.0011283792f + }, + { + -0.0038199491f, /* Filter 5 */ + 0.0164546659f, + 0.0154676597f, + -0.1568448230f, + 0.9744947974f, + 0.1568443643f, + 0.0154698286f, + -0.0164532877f, + -0.0038242967f + }, + { + -0.0057152767f, /* Filter 6 */ + 0.0152590213f, + 0.0228163087f, + -0.1612020164f, + 1.0309651039f, + 0.0875801110f, + 0.0267201501f, + -0.0134037738f, + -0.0061394831f + }, + { + -0.0073941287f, /* Filter 7 */ + 0.0132286539f, + 0.0296547979f, + -0.1591148676f, + 1.0763457753f, + 0.0260941722f, + 0.0349842710f, + -0.0096808822f, + -0.0079766730f + }, + { + -0.0087472825f, /* Filter 8 */ + 0.0104308721f, + 0.0355146231f, + -0.1496966290f, + 1.1095595051f, + -0.0269209682f, + 0.0402570324f, + -0.0055327477f, + -0.0092685626f + }, + { + -0.0096778115f, /* Filter 9 */ + 0.0069798134f, + 0.0399264862f, + -0.1322103702f, + 1.1298123136f, + -0.0710400038f, + 0.0426638320f, + -0.0012128224f, + -0.0099797659f + }, + { + -0.0101070340f, /* Filter 10 */ + 0.0030333009f, + 0.0424432507f, + -0.1061038872f, + 1.1366178484f, + -0.1061038872f, + 0.0424432507f, + 0.0030333009f, + -0.0101070340f + }, + { + -0.0099797659f, /* Filter 11 */ + -0.0012128224f, + 0.0426638320f, + -0.0710400038f, + 1.1298123136f, + -0.1322103702f, + 0.0399264862f, + 0.0069798134f, + -0.0096778115f + }, + { + -0.0092685626f, /* Filter 12 */ + -0.0055327477f, + 0.0402570324f, + -0.0269209682f, + 1.1095595051f, + -0.1496966290f, + 0.0355146231f, + 0.0104308721f, + -0.0087472825f + }, + { + -0.0079766730f, /* Filter 13 */ + -0.0096808822f, + 0.0349842710f, + 0.0260941722f, + 1.0763457753f, + -0.1591148676f, + 0.0296547979f, + 0.0132286539f, + -0.0073941287f + }, + { + -0.0061394831f, /* Filter 14 */ + -0.0134037738f, + 0.0267201501f, + 0.0875801110f, + 1.0309651039f, + -0.1612020164f, + 0.0228163087f, + 0.0152590213f, + -0.0057152767f + }, + { + -0.0038242967f, /* Filter 15 */ + -0.0164532877f, + 0.0154698286f, + 0.1568443643f, + 0.9744947974f, + -0.1568448230f, + 0.0154676597f, + 0.0164546659f, + -0.0038199491f + }, + { + -0.0011283792f, /* Filter 16 */ + -0.0186004475f, + 0.0013822552f, + 0.2329352195f, + 0.9082626683f, + -0.1470417557f, + 0.0080554403f, + 0.0167957238f, + -0.0018233575f + }, + { + 0.0018247182f, /* Filter 17 */ + -0.0196492903f, + -0.0152415667f, + 0.3146585634f, + 0.8338068363f, + -0.1328632049f, + 0.0009858079f, + 0.0163079778f, + 0.0001596234f + }, + { + 0.0048904515f, /* Filter 18 */ + -0.0194500407f, + -0.0339459430f, + 0.4006032722f, + 0.7528295479f, + -0.1154114754f, + -0.0053908083f, + 0.0150588729f, + 0.0020204744f + }, + { + 0.0079099936f, /* Filter 19 */ + -0.0179109014f, + -0.0541239470f, + 0.4891745311f, + 0.6671466059f, + -0.0957820135f, + -0.0107913392f, + 0.0131516633f, + 0.0036624469f + }, +}; + +/* Raised root cosine pulse shaping; Beta = 0.5; 4 symbols either + side of the centre. */ +/* Created with mkshape -r 0.1 0.5 45 -l and then split up */ +#define PULSESHAPER_4800_GAIN (4.9913162900f/5.0f) +#define PULSESHAPER_4800_COEFF_SETS 5 +static const float pulseshaper_4800[PULSESHAPER_4800_COEFF_SETS][V27TER_TX_FILTER_STEPS] = +{ + { + 0.0020173211f, /* Filter 0 */ + 0.0150576434f, + -0.0053888047f, + -0.1154099010f, + 0.7528286821f, + 0.4006013374f, + -0.0339462085f, + -0.0194477281f, + 0.0048918464f + }, + { + -0.0057162575f, /* Filter 1 */ + 0.0152563286f, + 0.0228163350f, + -0.1612000503f, + 1.0309660372f, + 0.0875788553f, + 0.0267182476f, + -0.0134032156f, + -0.0061365979f + }, + { + -0.0101052019f, /* Filter 2 */ + 0.0030314952f, + 0.0424414442f, + -0.1061032862f, + 1.1366196464f, + -0.1061032862f, + 0.0424414442f, + 0.0030314952f, + -0.0101052019f + }, + { + -0.0061365979f, /* Filter 3 */ + -0.0134032156f, + 0.0267182476f, + 0.0875788553f, + 1.0309660372f, + -0.1612000503f, + 0.0228163350f, + 0.0152563286f, + -0.0057162575f + }, + { + 0.0048918464f, /* Filter 4 */ + -0.0194477281f, + -0.0339462085f, + 0.4006013374f, + 0.7528286821f, + -0.1154099010f, + -0.0053888047f, + 0.0150576434f, + 0.0020173211f + }, +}; + +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->user_data)) == PUTBIT_END_OF_DATA) + { + /* End of real data. Switch to the fake get_bit routine, until we + have shut down completely. */ + s->current_get_bit = fake_get_bit; + s->in_training = TRUE; + bit = 1; + } + return scramble(s, bit); +} +/*- End of function --------------------------------------------------------*/ + +static complexf_t getbaud(v27ter_tx_state_t *s) +{ + 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 + }; + 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 */ + }; + 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 complex_setf(0.0, 0.0); + } + /* 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; + } + } + /* 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 --------------------------------------------------------*/ + +int v27ter_tx(v27ter_tx_state_t *s, int16_t amp[], int len) +{ + complexf_t x; + complexf_t z; + 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 */ + x.re = 0.0f; + x.im = 0.0f; + for (i = 0; i < V27TER_TX_FILTER_STEPS; i++) + { + x.re += pulseshaper_4800[4 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].re; + x.im += pulseshaper_4800[4 - 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) lrintf((x.re*z.re - x.im*z.im)*s->gain_4800); + } + } + 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 */ + x.re = 0.0f; + x.im = 0.0f; + for (i = 0; i < V27TER_TX_FILTER_STEPS; i++) + { + x.re += pulseshaper_2400[19 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].re; + x.im += pulseshaper_2400[19 - 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) lrintf((x.re*z.re - x.im*z.im)*s->gain_2400); + } + } + return sample; +} +/*- End of function --------------------------------------------------------*/ + +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; + s->gain_2400 = l/PULSESHAPER_2400_GAIN; + s->gain_4800 = l/PULSESHAPER_4800_GAIN; +} +/*- End of function --------------------------------------------------------*/ + +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->user_data = user_data; +} +/*- End of function --------------------------------------------------------*/ + +int v27ter_tx_restart(v27ter_tx_state_t *s, int rate, int tep) +{ + if (rate != 4800 && rate != 2400) + return -1; + s->bit_rate = rate; + cvec_zerof(s->rrc_filter, sizeof(s->rrc_filter)/sizeof(s->rrc_filter[0])); + 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 --------------------------------------------------------*/ + +v27ter_tx_state_t *v27ter_tx_init(v27ter_tx_state_t *s, int rate, int tep, get_bit_func_t get_bit, void *user_data) +{ + if (s == NULL) + { + if ((s = (v27ter_tx_state_t *) malloc(sizeof(*s))) == NULL) + return NULL; + } + memset(s, 0, sizeof(*s)); + s->get_bit = get_bit; + s->user_data = user_data; + s->carrier_phase_rate = dds_phase_ratef(CARRIER_NOMINAL_FREQ); + v27ter_tx_power(s, -14.0f); + v27ter_tx_restart(s, rate, tep); + return s; +} +/*- End of function --------------------------------------------------------*/ + +int v27ter_tx_release(v27ter_tx_state_t *s) +{ + free(s); + return 0; +} +/*- End of function --------------------------------------------------------*/ +/*- End of file ------------------------------------------------------------*/