--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/v17tx.c	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,475 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * v17tx.c - ITU V.17 modem transmit part
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2004 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: v17tx.c,v 1.75.4.1 2009/12/24 16:52:30 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/v17tx.h"
+
+#include "spandsp/private/logging.h"
+#include "spandsp/private/v17tx.h"
+
+#if defined(SPANDSP_USE_FIXED_POINT)
+#define SPANDSP_USE_FIXED_POINTx
+#endif
+
+#include "v17_v32bis_tx_constellation_maps.h"
+#if defined(SPANDSP_USE_FIXED_POINT)
+#include "v17_v32bis_tx_fixed_rrc.h"
+#else
+#include "v17_v32bis_tx_floating_rrc.h"
+#endif
+
+/*! The nominal frequency of the carrier, in Hertz */
+#define CARRIER_NOMINAL_FREQ        1800.0f
+
+/* Segments of the training sequence */
+/*! The start of the optional TEP, that may preceed the actual training, in symbols */
+#define V17_TRAINING_SEG_TEP_A      0
+/*! The mid point of the optional TEP, that may preceed the actual training, in symbols */
+#define V17_TRAINING_SEG_TEP_B      (V17_TRAINING_SEG_TEP_A + 480)
+/*! The start of training segment 1, in symbols */
+#define V17_TRAINING_SEG_1          (V17_TRAINING_SEG_TEP_B + 48)
+/*! The start of training segment 2, in symbols */
+#define V17_TRAINING_SEG_2          (V17_TRAINING_SEG_1 + 256)
+/*! The start of training segment 3, in symbols */
+#define V17_TRAINING_SEG_3          (V17_TRAINING_SEG_2 + 2976)
+/*! The start of training segment 4, in symbols */
+#define V17_TRAINING_SEG_4          (V17_TRAINING_SEG_3 + 64)
+/*! The start of training segment 4 in short training mode, in symbols */
+#define V17_TRAINING_SHORT_SEG_4    (V17_TRAINING_SEG_2 + 38)
+/*! The end of the training, in symbols */
+#define V17_TRAINING_END            (V17_TRAINING_SEG_4 + 48)
+#define V17_TRAINING_SHUTDOWN_A     (V17_TRAINING_END + 32)
+/*! The end of the shutdown sequence, in symbols */
+#define V17_TRAINING_SHUTDOWN_END   (V17_TRAINING_SHUTDOWN_A + 48)
+
+/*! The 16 bit pattern used in the bridge section of the training sequence */
+#define V17_BRIDGE_WORD             0x8880
+
+static __inline__ int scramble(v17_tx_state_t *s, int in_bit)
+{
+    int out_bit;
+
+    //out_bit = (in_bit ^ (s->scramble_reg >> s->scrambler_tap) ^ (s->scramble_reg >> (23 - 1))) & 1;
+    out_bit = (in_bit ^ (s->scramble_reg >> (18 - 1)) ^ (s->scramble_reg >> (23 - 1))) & 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 training_get(v17_tx_state_t *s)
+#else
+static __inline__ complexf_t training_get(v17_tx_state_t *s)
+#endif
+{
+    static const int cdba_to_abcd[4] =
+    {
+        2, 3, 1, 0
+    };
+    static const int dibit_to_step[4] =
+    {
+        1, 0, 2, 3
+    };
+#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 shift;
+
+    if (++s->training_step <= V17_TRAINING_SEG_3)
+    {
+        if (s->training_step <= V17_TRAINING_SEG_2)
+        {
+            if (s->training_step <= V17_TRAINING_SEG_TEP_B)
+            {
+                /* Optional segment: Unmodulated carrier (talker echo protection) */
+                return v17_v32bis_abcd_constellation[0];
+            }
+            if (s->training_step <= V17_TRAINING_SEG_1)
+            {
+                /* Optional segment: silence (talker echo protection) */
+                return zero;
+            }
+            /* Segment 1: ABAB... */
+            return v17_v32bis_abcd_constellation[(s->training_step & 1) ^ 1];
+        }
+        /* Segment 2: CDBA... */
+        /* Apply the scrambler */
+        bits = scramble(s, 1);
+        bits = (bits << 1) | scramble(s, 1);
+        s->constellation_state = cdba_to_abcd[bits];
+        if (s->short_train  &&  s->training_step == V17_TRAINING_SHORT_SEG_4)
+        {
+            /* Go straight to the ones test. */
+            s->training_step = V17_TRAINING_SEG_4;
+        }
+        return v17_v32bis_abcd_constellation[s->constellation_state];
+    }
+    /* Segment 3: Bridge... */
+    shift = ((s->training_step - V17_TRAINING_SEG_3 - 1) & 0x7) << 1;
+    //span_log(&s->logging, SPAN_LOG_FLOW, "Seg 3 shift %d\n", shift);
+    bits = scramble(s, V17_BRIDGE_WORD >> shift);
+    bits = (bits << 1) | scramble(s, V17_BRIDGE_WORD >> (shift + 1));
+    s->constellation_state = (s->constellation_state + dibit_to_step[bits]) & 3;
+    return v17_v32bis_abcd_constellation[s->constellation_state];
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ int diff_and_convolutional_encode(v17_tx_state_t *s, int q)
+{
+    static const uint8_t v32bis_4800_differential_encoder[4][4] =
+    {
+        {2, 3, 0, 1},
+        {0, 2, 1, 3},
+        {3, 1, 2, 0},
+        {1, 0, 3, 2}
+    };
+    static const uint8_t v17_differential_encoder[4][4] =
+    {
+        {0, 1, 2, 3},
+        {1, 2, 3, 0},
+        {2, 3, 0, 1},
+        {3, 0, 1, 2}
+    };
+    static const uint8_t v17_convolutional_coder[8][4] =
+    {
+        {0, 2, 3, 1},
+        {4, 7, 5, 6},
+        {1, 3, 2, 0},
+        {7, 4, 6, 5},
+        {2, 0, 1, 3},
+        {6, 5, 7, 4},
+        {3, 1, 0, 2},
+        {5, 6, 4, 7}
+    };
+
+    if (s->bits_per_symbol == 2)
+    {
+        /* 4800bps mode for V.32bis */
+        /* There is no trellis. We just differentially encode. */
+        s->diff = v32bis_4800_differential_encoder[s->diff][q & 0x03];
+        return s->diff;
+    }
+    /* Differentially encode */
+    s->diff = v17_differential_encoder[s->diff][q & 0x03];
+
+    /* Convolutionally encode the redundant bit */
+    s->convolution = v17_convolutional_coder[s->convolution][s->diff];
+
+    /* The final result is the combination of some uncoded bits, 2 differentially
+       encoded bits, and the convolutionally encoded redundant bit. */
+    return ((q << 1) & 0x78) | (s->diff << 1) | ((s->convolution >> 2) & 1);
+}
+/*- End of function --------------------------------------------------------*/
+
+static int fake_get_bit(void *user_data)
+{
+    return 1;
+}
+/*- End of function --------------------------------------------------------*/
+
+#if defined(SPANDSP_USE_FIXED_POINT)
+static __inline__ complexi16_t getbaud(v17_tx_state_t *s)
+#else
+static __inline__ complexf_t getbaud(v17_tx_state_t *s)
+#endif
+{
+    int i;
+    int bit;
+    int bits;
+
+    if (s->in_training)
+    {
+        if (s->training_step <= V17_TRAINING_END)
+        {
+            /* Send the training sequence */
+            if (s->training_step < V17_TRAINING_SEG_4)
+                return training_get(s);
+            /* The last step in training is to send some 1's */
+            if (++s->training_step > V17_TRAINING_END)
+            {
+                /* Training finished - commence normal operation. */
+                s->current_get_bit = s->get_bit;
+                s->in_training = FALSE;
+            }
+        }
+        else
+        {
+            if (++s->training_step > V17_TRAINING_SHUTDOWN_A)
+            {
+                /* The shutdown sequence is 32 bauds of all 1's, then 48 bauds
+                   of silence */
+#if defined(SPANDSP_USE_FIXED_POINT)
+                return complex_seti16(0, 0);
+#else
+                return complex_setf(0.0f, 0.0f);
+#endif
+            }
+            if (s->training_step == V17_TRAINING_SHUTDOWN_END)
+            {
+                if (s->status_handler)
+                    s->status_handler(s->status_user_data, SIG_STATUS_SHUTDOWN_COMPLETE);
+            }
+        }
+    }
+    bits = 0;
+    for (i = 0;  i < s->bits_per_symbol;  i++)
+    {
+        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;
+        }
+        bits |= (scramble(s, bit) << i);
+    }
+    return s->constellation[diff_and_convolutional_encode(s, bits)];
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE_NONSTD(int) v17_tx(v17_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 >= V17_TRAINING_SHUTDOWN_END)
+    {
+        /* Once we have sent the shutdown sequence, 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 + V17_TX_FILTER_STEPS] = getbaud(s);
+            if (++s->rrc_filter_step >= V17_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 < V17_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 < V17_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 --------------------------------------------------------*/
+
+SPAN_DECLARE(void) v17_tx_power(v17_tx_state_t *s, float power)
+{
+    /* The constellation design seems to keep the average power the same, regardless
+       of which bit rate is in use. */
+#if defined(SPANDSP_USE_FIXED_POINT)
+    s->gain = 0.223f*powf(10.0f, (power - DBM0_MAX_POWER)/20.0f)*16.0f*(32767.0f/30672.52f)*32768.0f/TX_PULSESHAPER_GAIN;
+#else
+    s->gain = 0.223f*powf(10.0f, (power - DBM0_MAX_POWER)/20.0f)*32768.0f/TX_PULSESHAPER_GAIN;
+#endif
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(void) v17_tx_set_get_bit(v17_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) v17_tx_set_modem_status_handler(v17_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 *) v17_tx_get_logging_state(v17_tx_state_t *s)
+{
+    return &s->logging;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) v17_tx_restart(v17_tx_state_t *s, int bit_rate, int tep, int short_train)
+{
+    switch (bit_rate)
+    {
+    case 14400:
+        s->bits_per_symbol = 6;
+        s->constellation = v17_v32bis_14400_constellation;
+        break;
+    case 12000:
+        s->bits_per_symbol = 5;
+        s->constellation = v17_v32bis_12000_constellation;
+        break;
+    case 9600:
+        s->bits_per_symbol = 4;
+        s->constellation = v17_v32bis_9600_constellation;
+        break;
+    case 7200:
+        s->bits_per_symbol = 3;
+        s->constellation = v17_v32bis_7200_constellation;
+        break;
+    case 4800:
+        /* This does not exist in the V.17 spec as a valid mode of operation.
+           However, it does exist in V.32bis, so it is here for completeness. */
+        s->bits_per_symbol = 2;
+        s->constellation = v17_v32bis_4800_constellation;
+        break;
+    default:
+        return -1;
+    }
+    s->bit_rate = bit_rate;
+    /* NB: some modems seem to use 3 instead of 1 for long training */
+    s->diff = (short_train)  ?  0  :  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->convolution = 0;
+    s->scramble_reg = 0x2ECDD5;
+    s->in_training = TRUE;
+    s->short_train = short_train;
+    s->training_step = (tep)  ?  V17_TRAINING_SEG_TEP_A  :  V17_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(v17_tx_state_t *) v17_tx_init(v17_tx_state_t *s, int bit_rate, int tep, get_bit_func_t get_bit, void *user_data)
+{
+    switch (bit_rate)
+    {
+    case 14400:
+    case 12000:
+    case 9600:
+    case 7200:
+    case 4800:
+        /* 4800 is an extension of V.17, to provide full converage of the V.32bis modes */
+        break;
+    default:
+        return NULL;
+    }
+    if (s == NULL)
+    {
+        if ((s = (v17_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.17 TX");
+    s->get_bit = get_bit;
+    s->get_bit_user_data = user_data;
+    //s->scrambler_tap = 18 - 1;
+    s->carrier_phase_rate = dds_phase_ratef(CARRIER_NOMINAL_FREQ);
+    v17_tx_power(s, -14.0f);
+    v17_tx_restart(s, bit_rate, tep, FALSE);
+    return s;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) v17_tx_release(v17_tx_state_t *s)
+{
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) v17_tx_free(v17_tx_state_t *s)
+{
+    free(s);
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/