--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/modem_connect_tones.c	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,321 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * modem_connect_tones.c - Generation and detection of tones
+ * associated with modems calling and answering calls.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2006 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: modem_connect_tones.c,v 1.6 2006/11/30 15:41:47 steveu Exp $
+ */
+ 
+/*! \file */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <inttypes.h>
+#include <stdlib.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/dds.h"
+#include "spandsp/tone_detect.h"
+#include "spandsp/tone_generate.h"
+#include "spandsp/super_tone_rx.h"
+#include "spandsp/modem_connect_tones.h"
+
+int modem_connect_tones_tx(modem_connect_tones_tx_state_t *s,
+                           int16_t amp[],
+                           int len)
+{
+    int mod;
+    int i;
+
+    switch (s->tone_type)
+    {
+    case MODEM_CONNECT_TONES_FAX_CNG:
+    case MODEM_CONNECT_TONES_FAX_CED:
+        len = tone_gen(&s->tone_tx, amp, len);
+        break;
+    case MODEM_CONNECT_TONES_EC_DISABLE:
+        for (i = 0;  i < len;  i++)
+        {
+            if (--s->hop_timer <= 0)
+            {
+                s->hop_timer = ms_to_samples(450);
+                s->tone_phase += 0x80000000;
+            }
+            amp[i] = dds_mod(&s->tone_phase, s->tone_phase_rate, s->level, 0);
+        }
+        break;
+    case MODEM_CONNECT_TONES_EC_DISABLE_MOD:
+        for (i = 0;  i < len;  i++)
+        {
+            mod = s->level + dds_mod(&s->mod_phase, s->mod_phase_rate, s->mod_level, 0);
+            if (--s->hop_timer <= 0)
+            {
+                s->hop_timer = ms_to_samples(450);
+                s->tone_phase += 0x80000000;
+            }
+            amp[i] = dds_mod(&s->tone_phase, s->tone_phase_rate, mod, 0);
+        }
+        break;
+    }
+    return len;
+}
+/*- End of function --------------------------------------------------------*/
+
+modem_connect_tones_tx_state_t *modem_connect_tones_tx_init(modem_connect_tones_tx_state_t *s,
+                                                            int tone_type)
+{
+    tone_gen_descriptor_t tone_desc;
+
+    s->tone_type = tone_type;
+    switch (s->tone_type)
+    {
+    case MODEM_CONNECT_TONES_FAX_CNG:
+        make_tone_gen_descriptor(&tone_desc,
+                                 1100,
+                                 -11,
+                                 0,
+                                 0,
+                                 500,
+                                 3000,
+                                 0,
+                                 0,
+                                 TRUE);
+        tone_gen_init(&s->tone_tx, &tone_desc);
+        break;
+    case MODEM_CONNECT_TONES_FAX_CED:
+        make_tone_gen_descriptor(&tone_desc,
+                                 2100,
+                                 -11,
+                                 0,
+                                 0,
+                                 2600,
+                                 0,
+                                 0,
+                                 0,
+                                 FALSE);
+        tone_gen_init(&s->tone_tx, &tone_desc);
+        break;
+    case MODEM_CONNECT_TONES_EC_DISABLE:
+    case MODEM_CONNECT_TONES_EC_DISABLE_MOD:
+        s->tone_phase_rate = dds_phase_rate(2100.0);
+        s->mod_phase_rate = dds_phase_rate(15.0);
+        s->tone_phase = 0;
+        s->mod_phase = 0;
+        s->hop_timer = ms_to_samples(450);
+        s->level = dds_scaling_dbm0(-12);
+        if (s->tone_type == MODEM_CONNECT_TONES_EC_DISABLE_MOD)
+            s->mod_level = s->level/5;
+        else
+            s->mod_level = 0;
+    }
+    return s;
+}
+/*- End of function --------------------------------------------------------*/
+
+int modem_connect_tones_rx(modem_connect_tones_rx_state_t *s, const int16_t amp[], int len)
+{
+    int i;
+    int16_t notched;
+    float v1;
+    float famp;
+    
+    switch (s->tone_type)
+    {
+    case MODEM_CONNECT_TONES_FAX_CNG:
+        for (i = 0;  i < len;  i++)
+        {
+            /* A Cauer notch at 1100Hz, spread just wide enough to meet our detection bandwidth
+               criteria. */
+            famp = amp[i];
+            v1 = 0.792928f*famp + 1.0018744927985f*s->z1 - 0.54196833412465f*s->z2;
+            famp = v1 - 1.2994747954630f*s->z1 + s->z2;
+            s->z2 = s->z1;
+            s->z1 = v1;
+            notched = rintf(famp);
+
+            /* Estimate the overall energy in the channel, and the energy in
+               the notch (i.e. overall channel energy - tone energy => noise).
+               Use abs instead of multiply for speed (is it really faster?). */
+            s->channel_level += ((abs(amp[i]) - s->channel_level) >> 5);
+            s->notch_level += ((abs(notched) - s->notch_level) >> 5);
+            if (s->channel_level > 70  &&  s->notch_level*6 < s->channel_level)
+            {
+                /* There is adequate energy in the channel, and it is mostly at 1100Hz. */
+                if (!s->tone_present)
+                {
+                    if (++s->tone_cycle_duration >= ms_to_samples(415))
+                    {
+                        if (s->tone_callback)
+                            s->tone_callback(s->callback_data, TRUE);
+                        else
+                            s->hit = TRUE;
+                        s->tone_present = TRUE;
+                    }
+                }
+            }
+            else
+            {
+                s->tone_cycle_duration = 0;
+            }
+        }
+        break;
+    case MODEM_CONNECT_TONES_FAX_CED:
+        for (i = 0;  i < len;  i++)
+        {
+            /* A Cauer notch at 2100Hz, spread just wide enough to meet our detection bandwidth
+               criteria. */
+            famp = amp[i];
+            v1 = 0.76000f*famp - 0.1183852f*s->z1 - 0.5104039f*s->z2;
+            famp = v1 + 0.1567596f*s->z1 + s->z2;
+            s->z2 = s->z1;
+            s->z1 = v1;
+            notched = rintf(famp);
+            /* Estimate the overall energy in the channel, and the energy in
+               the notch (i.e. overall channel energy - tone energy => noise).
+               Use abs instead of multiply for speed (is it really faster?). */
+            s->channel_level += ((abs(amp[i]) - s->channel_level) >> 5);
+            s->notch_level += ((abs(notched) - s->notch_level) >> 5);
+            if (s->channel_level > 70  &&  s->notch_level*6 < s->channel_level)
+            {
+                /* There is adequate energy in the channel, and it is mostly at 2100Hz. */
+                if (!s->tone_present)
+                {
+                    if (++s->tone_cycle_duration >= ms_to_samples(500))
+                    {
+                        if (s->tone_callback)
+                            s->tone_callback(s->callback_data, TRUE);
+                        else
+                            s->hit = TRUE;
+                        s->tone_present = TRUE;
+                    }
+                }
+            }
+            else
+            {
+                s->tone_cycle_duration = 0;
+            }
+        }
+        break;
+    case MODEM_CONNECT_TONES_EC_DISABLE:
+    case MODEM_CONNECT_TONES_EC_DISABLE_MOD:
+        for (i = 0;  i < len;  i++)
+        {
+            /* A Cauer notch at 2100Hz, spread just wide enough to meet our detection bandwidth
+               criteria. */
+            /* This is actually centred at 2095Hz, but gets the balance we want, due
+               to the asymmetric walls of the notch */
+            famp = amp[i];
+            v1 = 0.76000f*famp - 0.1183852f*s->z1 - 0.5104039f*s->z2;
+            famp = v1 + 0.1567596f*s->z1 + s->z2;
+            s->z2 = s->z1;
+            s->z1 = v1;
+            notched = rintf(famp);
+            /* Estimate the overall energy in the channel, and the energy in
+               the notch (i.e. overall channel energy - tone energy => noise).
+               Use abs instead of multiply for speed (is it really faster?).
+               Damp the overall energy a little more for a stable result.
+               Damp the notch energy a little less, so we don't damp out the
+               blip every time the phase reverses */
+            s->channel_level += ((abs(amp[i]) - s->channel_level) >> 5);
+            s->notch_level += ((abs(notched) - s->notch_level) >> 4);
+            if (s->channel_level > 280)
+            {
+                /* There is adequate energy in the channel. Is it mostly at 2100Hz? */
+                if (s->notch_level*6 < s->channel_level)
+                {
+                    /* The notch says yes, so we have the tone. */
+                    if (!s->tone_present)
+                    {
+                        /* Do we get a kick every 450+-25ms? */
+                        if (s->tone_cycle_duration >= ms_to_samples(425)
+                            &&
+                            s->tone_cycle_duration <= ms_to_samples(475))
+                        {
+                            if (++s->good_cycles > 2)
+                            {
+                                if (s->tone_callback)
+                                    s->tone_callback(s->callback_data, TRUE);
+                                else
+                                    s->hit = TRUE;
+                            }
+                        }
+                        s->tone_cycle_duration = 0;
+                        s->tone_present = TRUE;
+                    }
+                }
+                else
+                {
+                    s->tone_present = FALSE;
+                }
+                s->tone_cycle_duration++;
+            }
+            else
+            {
+                s->tone_present = FALSE;
+                s->tone_cycle_duration = 0;
+                s->good_cycles = 0;
+            }
+        }
+    }
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int modem_connect_tones_rx_get(modem_connect_tones_rx_state_t *s)
+{
+    int x;
+    
+    x = s->hit;
+    s->hit = FALSE;
+    return x;
+}
+/*- End of function --------------------------------------------------------*/
+
+modem_connect_tones_rx_state_t *modem_connect_tones_rx_init(modem_connect_tones_rx_state_t *s,
+                                                            int tone_type,
+                                                            tone_report_func_t tone_callback,
+                                                            void *user_data)
+{
+    s->tone_type = tone_type;
+    s->channel_level = 0;
+    s->notch_level = 0;    
+    s->tone_present = FALSE;
+    s->tone_cycle_duration = 0;
+    s->good_cycles = 0;
+    s->hit = FALSE;
+    s->tone_callback = tone_callback;
+    s->callback_data = user_data;
+    s->z1 = 0.0f;
+    s->z2 = 0.0f;
+    return s;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/