--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/v29tx.c	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,459 @@
+/*
+ * 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 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: v29tx.c,v 1.58 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/v29tx.h"
+
+#define CARRIER_NOMINAL_FREQ        1700.0f
+
+/* Segments of the training sequence */
+#define V29_TRAINING_SEG_TEP        0
+#define V29_TRAINING_SEG_1          (V29_TRAINING_SEG_TEP + 480)
+#define V29_TRAINING_SEG_2          (V29_TRAINING_SEG_1 + 48)
+#define V29_TRAINING_SEG_3          (V29_TRAINING_SEG_2 + 128)
+#define V29_TRAINING_SEG_4          (V29_TRAINING_SEG_3 + 384)
+#define V29_TRAINING_END            (V29_TRAINING_SEG_4 + 48)
+#define V29_TRAINING_SHUTDOWN_END   (V29_TRAINING_END + 32)
+
+/* Raised root cosine pulse shaping; Beta = 0.25; 4 symbols either
+   side of the centre. */
+/* Created with mkshape -r 0.05 0.25 91 -l and then split up */
+#define PULSESHAPER_GAIN            (9.9888356312f/10.0f)
+#define PULSESHAPER_COEFF_SETS      10
+
+static const float pulseshaper[PULSESHAPER_COEFF_SETS][V29_TX_FILTER_STEPS] =
+{
+    {
+        -0.0029426223f,         /* Filter 0 */
+        -0.0183060118f,
+         0.0653192857f,
+        -0.1703207714f,
+         0.6218069936f,
+         0.6218069936f,
+        -0.1703207714f,
+         0.0653192857f,
+        -0.0183060118f
+    },
+    {
+         0.0031876922f,         /* Filter 1 */
+        -0.0300884145f,
+         0.0832744718f,
+        -0.1974255221f,
+         0.7664229820f,
+         0.4670580725f,
+        -0.1291107519f,
+         0.0424189243f,
+        -0.0059810465f
+    },
+    {
+         0.0097229236f,         /* Filter 2 */
+        -0.0394811291f,
+         0.0931039664f,
+        -0.2043906784f,
+         0.8910868760f,
+         0.3122713836f,
+        -0.0802880559f,
+         0.0179050490f,
+         0.0052057308f
+    },
+    {
+         0.0156117223f,         /* Filter 3 */
+        -0.0447125347f,
+         0.0922040267f,
+        -0.1862939416f,
+         0.9870942864f,
+         0.1669790517f,
+        -0.0301581072f,
+        -0.0051358510f,
+         0.0139350286f
+    },
+    {
+         0.0197702545f,         /* Filter 4 */
+        -0.0443470335f,
+         0.0789538534f,
+        -0.1399184160f,
+         1.0476130256f,
+         0.0393903028f,
+         0.0157339854f,
+        -0.0241879599f,
+         0.0193774571f
+    },
+    {
+         0.0212455717f,         /* Filter 5 */
+        -0.0375307894f,
+         0.0530516472f,
+        -0.0642195521f,
+         1.0682849922f,
+        -0.0642195521f,
+         0.0530516472f,
+        -0.0375307894f,
+         0.0212455717f
+    },
+    {
+         0.0193774571f,         /* Filter 6 */
+        -0.0241879599f,
+         0.0157339854f,
+         0.0393903028f,
+         1.0476130256f,
+        -0.1399184160f,
+         0.0789538534f,
+        -0.0443470335f,
+         0.0197702545f
+    },
+    {
+         0.0139350286f,         /* Filter 7 */
+        -0.0051358510f,
+        -0.0301581072f,
+         0.1669790517f,
+         0.9870942864f,
+        -0.1862939416f,
+         0.0922040267f,
+        -0.0447125347f,
+         0.0156117223f
+    },
+    {
+         0.0052057308f,         /* Filter 8 */
+         0.0179050490f,
+        -0.0802880559f,
+         0.3122713836f,
+         0.8910868760f,
+        -0.2043906784f,
+         0.0931039664f,
+        -0.0394811291f,
+         0.0097229236f
+    },
+    {
+        -0.0059810465f,         /* Filter 9 */
+         0.0424189243f,
+        -0.1291107519f,
+         0.4670580725f,
+         0.7664229820f,
+        -0.1974255221f,
+         0.0832744718f,
+        -0.0300884145f,
+         0.0031876922f
+    },
+};
+
+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->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;
+    }
+    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 --------------------------------------------------------*/
+
+static __inline__ complexf_t getbaud(v29_tx_state_t *s)
+{
+    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
+    };
+    static const complexf_t constellation[16] =
+    {
+        { 3.0,  0.0},   /*   0deg low  */
+        { 1.0,  1.0},   /*  45deg low  */
+        { 0.0,  3.0},   /*  90deg low  */
+        {-1.0,  1.0},   /* 135deg low  */
+        {-3.0,  0.0},   /* 180deg low  */
+        {-1.0, -1.0},   /* 225deg low  */
+        { 0.0, -3.0},   /* 270deg low  */
+        { 1.0, -1.0},   /* 315deg low  */
+        { 5.0,  0.0},   /*   0deg high */
+        { 3.0,  3.0},   /*  45deg high */
+        { 0.0,  5.0},   /*  90deg high */
+        {-3.0,  3.0},   /* 135deg high */
+        {-5.0,  0.0},   /* 180deg high */
+        {-3.0, -3.0},   /* 225deg high */
+        { 0.0, -5.0},   /* 270deg high */
+        { 3.0, -3.0}    /* 315deg high */
+    };
+    static const complexf_t abab[6] =
+    {
+        { 3.0, -3.0},   /* 315deg high 9600 */
+        {-3.0,  0.0},   /* 180deg low       */
+        { 1.0, -1.0},   /* 315deg low 7200  */
+        {-3.0,  0.0},   /* 180deg low       */
+        { 0.0, -3.0},   /* 270deg low 4800  */
+        {-3.0,  0.0}    /* 180deg low       */
+    };
+    static const complexf_t cdcd[6] =
+    {
+        { 3.0,  0.0},   /*   0deg low 9600  */
+        {-3.0,  3.0},   /* 135deg high      */
+        { 3.0,  0.0},   /*   0deg low 7200  */
+        {-1.0,  1.0},   /* 135deg low       */
+        { 3.0,  0.0},   /*   0deg low 4800  */
+        { 0.0,  3.0}    /*  90deg low       */
+    };
+    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 constellation[0];
+                }
+                if (s->training_step <= V29_TRAINING_SEG_2)
+                {
+                    /* Segment 1: silence */
+                    return complex_setf(0.0f, 0.0f);
+                }
+                /* Segment 2: ABAB... */
+                return abab[(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 cdcd[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;
+        }
+    }
+    /* 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 constellation[amp | s->constellation_state];
+}
+/*- End of function --------------------------------------------------------*/
+
+int v29_tx(v29_tx_state_t *s, int16_t amp[], int len)
+{
+    complexf_t x;
+    complexf_t z;
+    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 */
+        x.re = 0.0f;
+        x.im = 0.0f;
+        for (i = 0;  i < V29_TX_FILTER_STEPS;  i++)
+        {
+            x.re += pulseshaper[9 - s->baud_phase][i]*s->rrc_filter[i + s->rrc_filter_step].re;
+            x.im += pulseshaper[9 - 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);
+    }
+    return sample;
+}
+/*- End of function --------------------------------------------------------*/
+
+static void set_working_gain(v29_tx_state_t *s)
+{
+    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;
+    }
+}
+/*- End of function --------------------------------------------------------*/
+
+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/PULSESHAPER_GAIN;
+    set_working_gain(s);
+}
+/*- End of function --------------------------------------------------------*/
+
+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->user_data = user_data;
+}
+/*- End of function --------------------------------------------------------*/
+
+int v29_tx_restart(v29_tx_state_t *s, int rate, int tep)
+{
+    span_log(&s->logging, SPAN_LOG_FLOW, "Restarting V.29\n");
+    s->bit_rate = 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;
+    }
+    cvec_zerof(s->rrc_filter, sizeof(s->rrc_filter)/sizeof(s->rrc_filter[0]));
+    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 --------------------------------------------------------*/
+
+v29_tx_state_t *v29_tx_init(v29_tx_state_t *s, int rate, int tep, get_bit_func_t get_bit, void *user_data)
+{
+    if (s == NULL)
+    {
+        if ((s = (v29_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);
+    v29_tx_power(s, -14.0f);
+    v29_tx_restart(s, rate, tep);
+    return s;
+}
+/*- End of function --------------------------------------------------------*/
+
+int v29_tx_release(v29_tx_state_t *s)
+{
+    free(s);
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/