270 lines
8.4 KiB
C
270 lines
8.4 KiB
C
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/*
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* SpanDSP - a series of DSP components for telephony
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*
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* super_tone_tx.c - Flexible telephony supervisory tone generation.
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2003 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id: super_tone_tx.c,v 1.25 2008/07/02 14:48:26 steveu Exp $
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*/
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/*! \file */
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#if defined(HAVE_CONFIG_H)
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#include "config.h"
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <ctype.h>
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#include <time.h>
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#include <inttypes.h>
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#include "floating_fudge.h"
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#if defined(HAVE_TGMATH_H)
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#include <tgmath.h>
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#endif
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#if defined(HAVE_MATH_H)
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#include <math.h>
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#endif
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#include "spandsp/telephony.h"
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#include "spandsp/complex.h"
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#include "spandsp/dds.h"
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#include "spandsp/tone_generate.h"
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#include "spandsp/super_tone_tx.h"
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/*
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The tone played to wake folk up when they have left the phone off hook is an
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oddity amongst supervisory tones. It is designed to sound loud and nasty. Most
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tones are one or two pure sine pitches, or one AM moduluated pitch. This alert
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tone varies between countries, but AT&T are a typical example.
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AT&T Receiver Off-Hook Tone is 1400 Hz, 2060 Hz, 2450 Hz and 2600 Hz at 0dBm0/frequency
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on and off every .1 second. On some older space division switching systems
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Receiver Off-Hook was 1400 Hz, 2060 Hz, 2450 Hz and 2600 Hz at +5 VU on and
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off every .1 second. On a No. 5 ESS this continues for 30 seconds. On a No.
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2/2B ESS this continues for 40 seconds. On some other AT&T switches there are
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two iterations of 50 seconds each.
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*/
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super_tone_tx_step_t *super_tone_tx_make_step(super_tone_tx_step_t *s,
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float f1,
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float l1,
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float f2,
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float l2,
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int length,
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int cycles)
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{
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if (s == NULL)
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{
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if ((s = (super_tone_tx_step_t *) malloc(sizeof(*s))) == NULL)
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return NULL;
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}
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if (f1 >= 1.0f)
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{
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s->tone[0].phase_rate = dds_phase_ratef(f1);
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s->tone[0].gain = dds_scaling_dbm0f(l1);
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}
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else
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{
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s->tone[0].phase_rate = 0;
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s->tone[0].gain = 0.0f;
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}
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if (f2 >= 1.0f)
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{
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s->tone[1].phase_rate = dds_phase_ratef(f2);
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s->tone[1].gain = dds_scaling_dbm0f(l2);
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}
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else
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{
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s->tone[1].phase_rate = 0;
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s->tone[1].gain = 0.0f;
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}
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s->tone_on = (f1 > 0.0f);
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s->length = length*SAMPLE_RATE/1000;
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s->cycles = cycles;
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s->next = NULL;
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s->nest = NULL;
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return s;
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}
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/*- End of function --------------------------------------------------------*/
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void super_tone_tx_free(super_tone_tx_step_t *s)
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{
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super_tone_tx_step_t *t;
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while (s)
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{
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/* Follow nesting... */
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if (s->nest)
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super_tone_tx_free(s->nest);
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t = s;
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s = s->next;
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free(t);
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}
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}
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/*- End of function --------------------------------------------------------*/
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super_tone_tx_state_t *super_tone_tx_init(super_tone_tx_state_t *s, super_tone_tx_step_t *tree)
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{
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if (tree == NULL)
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return NULL;
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if (s == NULL)
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{
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if ((s = (super_tone_tx_state_t *) malloc(sizeof(*s))) == NULL)
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return NULL;
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}
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memset(s, 0, sizeof(*s));
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s->level = 0;
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s->levels[0] = tree;
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s->cycles[0] = tree->cycles;
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s->current_position = 0;
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return s;
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}
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/*- End of function --------------------------------------------------------*/
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int super_tone_tx(super_tone_tx_state_t *s, int16_t amp[], int max_samples)
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{
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int samples;
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int limit;
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int len;
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int i;
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float xamp;
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super_tone_tx_step_t *tree;
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if (s->level < 0 || s->level > 3)
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return 0;
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samples = 0;
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tree = s->levels[s->level];
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while (tree && samples < max_samples)
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{
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if (tree->tone_on)
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{
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/* A period of tone. A length of zero means infinite length. */
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if (s->current_position == 0)
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{
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/* New step - prepare the tone generator */
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for (i = 0; i < 4; i++)
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s->tone[i] = tree->tone[i];
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}
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len = tree->length - s->current_position;
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if (tree->length == 0)
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{
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len = max_samples - samples;
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/* We just need to make current position non-zero */
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s->current_position = 1;
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}
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else if (len > max_samples - samples)
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{
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len = max_samples - samples;
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s->current_position += len;
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}
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else
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{
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s->current_position = 0;
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}
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if (s->tone[0].phase_rate < 0)
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{
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for (limit = len + samples; samples < limit; samples++)
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{
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/* There must be two, and only two tones */
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xamp = dds_modf(&s->phase[0], -s->tone[0].phase_rate, s->tone[0].gain, 0)
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*(1.0f + dds_modf(&s->phase[1], s->tone[1].phase_rate, s->tone[1].gain, 0));
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amp[samples] = (int16_t) lrintf(xamp);
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}
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}
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else
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{
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for (limit = len + samples; samples < limit; samples++)
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{
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xamp = 0.0f;
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for (i = 0; i < 4; i++)
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{
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if (s->tone[i].phase_rate == 0)
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break;
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xamp += dds_modf(&s->phase[i], s->tone[i].phase_rate, s->tone[i].gain, 0);
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}
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amp[samples] = (int16_t) lrintf(xamp);
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}
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}
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if (s->current_position)
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return samples;
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}
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else if (tree->length)
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{
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/* A period of silence. The length must always
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be explicitly stated. A length of zero does
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not give infinite silence. */
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len = tree->length - s->current_position;
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if (len > max_samples - samples)
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{
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len = max_samples - samples;
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s->current_position += len;
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}
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else
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{
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s->current_position = 0;
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}
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memset(amp + samples, 0, sizeof(uint16_t)*len);
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samples += len;
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if (s->current_position)
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return samples;
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}
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/* Nesting has priority... */
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if (tree->nest)
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{
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tree = tree->nest;
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s->levels[++s->level] = tree;
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s->cycles[s->level] = tree->cycles;
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}
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else
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{
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/* ...Next comes repeating, and finally moving forward a step. */
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/* When repeating, note that zero cycles really means endless cycles. */
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while (tree->cycles && --s->cycles[s->level] <= 0)
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{
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tree = tree->next;
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if (tree)
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{
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/* A fresh new step. */
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s->levels[s->level] = tree;
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s->cycles[s->level] = tree->cycles;
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break;
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}
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/* If we are nested we need to pop, otherwise this is the end. */
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if (s->level <= 0)
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{
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/* Mark the tone as completed */
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s->levels[0] = NULL;
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break;
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}
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tree = s->levels[--s->level];
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}
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}
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}
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return samples;
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}
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/*- End of function --------------------------------------------------------*/
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/*- End of file ------------------------------------------------------------*/
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