spandsp/src/dtmf.c

/*
 * SpanDSP - a series of DSP components for telephony
 *
 * dtmf.c - DTMF generation and detection.
 *
 * Written by Steve Underwood <steveu@coppice.org>
 *
 * Copyright (C) 2001-2003, 2005, 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 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: dtmf.c,v 1.43 2008/07/02 14:48:25 steveu Exp $
 */

/*! \file dtmf.h */

#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif

#include <inttypes.h>
#include <stdlib.h>
#include "floating_fudge.h"
#if defined(HAVE_TGMATH_H)
#include <tgmath.h>
#endif
#if defined(HAVE_MATH_H)
#include <math.h>
#endif
#include <string.h>
#include <stdio.h>
#include <time.h>
#include <fcntl.h>

#include "spandsp/telephony.h"
#include "spandsp/queue.h"
#include "spandsp/complex.h"
#include "spandsp/dds.h"
#include "spandsp/tone_detect.h"
#include "spandsp/tone_generate.h"
#include "spandsp/super_tone_rx.h"
#include "spandsp/dtmf.h"

#define DEFAULT_DTMF_TX_LEVEL       -10
#define DEFAULT_DTMF_TX_ON_TIME     50
#define DEFAULT_DTMF_TX_OFF_TIME    55

#if defined(SPANDSP_USE_FIXED_POINT)
#define DTMF_THRESHOLD              10438           /* -42dBm0 */
#define DTMF_NORMAL_TWIST           6.309f          /* 8dB */
#define DTMF_REVERSE_TWIST          2.512f          /* 4dB */
#define DTMF_RELATIVE_PEAK_ROW      6.309f          /* 8dB */
#define DTMF_RELATIVE_PEAK_COL      6.309f          /* 8dB */
#define DTMF_TO_TOTAL_ENERGY        83.868f         /* -0.85dB */
#define DTMF_POWER_OFFSET           68.251f         /* 10*log(256.0*256.0*DTMF_SAMPLES_PER_BLOCK) */
#define DTMF_SAMPLES_PER_BLOCK      102
#else
#define DTMF_THRESHOLD              171032462.0f    /* -42dBm0 [((DTMF_SAMPLES_PER_BLOCK*32768.0/1.4142)*10^((-42 - DBM0_MAX_SINE_POWER)/20.0))^2 => 171032462.0] */
#define DTMF_NORMAL_TWIST           6.309f          /* 8dB [10^(8/10) => 6.309] */
#define DTMF_REVERSE_TWIST          2.512f          /* 4dB */
#define DTMF_RELATIVE_PEAK_ROW      6.309f          /* 8dB */
#define DTMF_RELATIVE_PEAK_COL      6.309f          /* 8dB */
#define DTMF_TO_TOTAL_ENERGY        83.868f         /* -0.85dB [DTMF_SAMPLES_PER_BLOCK*10^(-0.85/10.0)] */
#define DTMF_POWER_OFFSET           110.395f        /* 10*log(32768.0*32768.0*DTMF_SAMPLES_PER_BLOCK) */
#define DTMF_SAMPLES_PER_BLOCK      102
#endif

static const float dtmf_row[] =
{
     697.0f,  770.0f,  852.0f,  941.0f
};
static const float dtmf_col[] =
{
    1209.0f, 1336.0f, 1477.0f, 1633.0f
};

static const char dtmf_positions[] = "123A" "456B" "789C" "*0#D";

static goertzel_descriptor_t dtmf_detect_row[4];
static goertzel_descriptor_t dtmf_detect_col[4];

static int dtmf_tx_inited = FALSE;
static tone_gen_descriptor_t dtmf_digit_tones[16];

int dtmf_rx(dtmf_rx_state_t *s, const int16_t amp[], int samples)
{
#if defined(SPANDSP_USE_FIXED_POINT)
    int32_t row_energy[4];
    int32_t col_energy[4];
    int16_t xamp;
    float famp;
#else
    float row_energy[4];
    float col_energy[4];
    float xamp;
    float famp;
#endif
    float v1;
    int i;
    int j;
    int sample;
    int best_row;
    int best_col;
    int limit;
    uint8_t hit;

    hit = 0;
    for (sample = 0;  sample < samples;  sample = limit)
    {
        /* The block length is optimised to meet the DTMF specs. */
        if ((samples - sample) >= (DTMF_SAMPLES_PER_BLOCK - s->current_sample))
            limit = sample + (DTMF_SAMPLES_PER_BLOCK - s->current_sample);
        else
            limit = samples;
        /* The following unrolled loop takes only 35% (rough estimate) of the
           time of a rolled loop on the machine on which it was developed */
        for (j = sample;  j < limit;  j++)
        {
            xamp = amp[j];
            if (s->filter_dialtone)
            {
                famp = xamp;
                /* Sharp notches applied at 350Hz and 440Hz - the two common dialtone frequencies.
                   These are rather high Q, to achieve the required narrowness, without using lots of
                   sections. */
                v1 = 0.98356f*famp + 1.8954426f*s->z350[0] - 0.9691396f*s->z350[1];
                famp = v1 - 1.9251480f*s->z350[0] + s->z350[1];
                s->z350[1] = s->z350[0];
                s->z350[0] = v1;

                v1 = 0.98456f*famp + 1.8529543f*s->z440[0] - 0.9691396f*s->z440[1];
                famp = v1 - 1.8819938f*s->z440[0] + s->z440[1];
                s->z440[1] = s->z440[0];
                s->z440[0] = v1;
                xamp = famp;
            }
            xamp = goertzel_preadjust_amp(xamp);
#if defined(SPANDSP_USE_FIXED_POINT)
            s->energy += ((int32_t) xamp*xamp);
#else
            s->energy += xamp*xamp;
#endif
            goertzel_samplex(&s->row_out[0], xamp);
            goertzel_samplex(&s->col_out[0], xamp);
            goertzel_samplex(&s->row_out[1], xamp);
            goertzel_samplex(&s->col_out[1], xamp);
            goertzel_samplex(&s->row_out[2], xamp);
            goertzel_samplex(&s->col_out[2], xamp);
            goertzel_samplex(&s->row_out[3], xamp);
            goertzel_samplex(&s->col_out[3], xamp);
        }
        s->current_sample += (limit - sample);
        if (s->current_sample < DTMF_SAMPLES_PER_BLOCK)
            continue;

        /* We are at the end of a DTMF detection block */
        /* Find the peak row and the peak column */
        row_energy[0] = goertzel_result(&s->row_out[0]);
        best_row = 0;
        col_energy[0] = goertzel_result(&s->col_out[0]);
        best_col = 0;
        for (i = 1;  i < 4;  i++)
        {
            row_energy[i] = goertzel_result(&s->row_out[i]);
            if (row_energy[i] > row_energy[best_row])
                best_row = i;
            col_energy[i] = goertzel_result(&s->col_out[i]);
            if (col_energy[i] > col_energy[best_col])
                best_col = i;
        }
        hit = 0;
        /* Basic signal level test and the twist test */
        if (row_energy[best_row] >= s->threshold
            &&
            col_energy[best_col] >= s->threshold
            &&
            col_energy[best_col] < row_energy[best_row]*s->reverse_twist
            &&
            col_energy[best_col]*s->normal_twist > row_energy[best_row])
        {
            /* Relative peak test ... */
            for (i = 0;  i < 4;  i++)
            {
                if ((i != best_col  &&  col_energy[i]*DTMF_RELATIVE_PEAK_COL > col_energy[best_col])
                    ||
                    (i != best_row  &&  row_energy[i]*DTMF_RELATIVE_PEAK_ROW > row_energy[best_row]))
                {
                    break;
                }
            }
            /* ... and fraction of total energy test */
            if (i >= 4
                &&
                (row_energy[best_row] + col_energy[best_col]) > DTMF_TO_TOTAL_ENERGY*s->energy)
            {
                /* Got a hit */
                hit = dtmf_positions[(best_row << 2) + best_col];
            }
        }
        /* The logic in the next test should ensure the following for different successive hit patterns:
                -----ABB = start of digit B.
                ----B-BB = start of digit B
                ----A-BB = start of digit B
                BBBBBABB = still in digit B.
                BBBBBB-- = end of digit B
                BBBBBBC- = end of digit B
                BBBBACBB = B ends, then B starts again.
                BBBBBBCC = B ends, then C starts.
                BBBBBCDD = B ends, then D starts.
           This can work with:
                - Back to back differing digits. Back-to-back digits should
                  not happen. The spec. says there should be a gap between digits.
                  However, many real phones do not impose a gap, and rolling across
                  the keypad can produce little or no gap.
                - It tolerates nasty phones that give a very wobbly start to a digit.
                - VoIP can give sample slips. The phase jumps that produces will cause
                  the block it is in to give no detection. This logic will ride over a
                  single missed block, and not falsely declare a second digit. If the
                  hiccup happens in the wrong place on a minimum length digit, however
                  we would still fail to detect that digit. Could anything be done to
                  deal with that? Packet loss is clearly a no-go zone.
                  Note this is only relevant to VoIP using A-law, u-law or similar.
                  Low bit rate codecs scramble DTMF too much for it to be recognised,
                  and often slip in units larger than a sample. */
        if (hit != s->in_digit)
        {
            if (s->last_hit != s->in_digit)
            {
                /* We have two successive indications that something has changed. */
                /* To declare digit on, the hits must agree. Otherwise we declare tone off. */
                hit = (hit  &&  hit == s->last_hit)  ?  hit   :  0;
                if (s->realtime_callback)
                {
                    /* Avoid reporting multiple no digit conditions on flaky hits */
                    if (s->in_digit  ||  hit)
                    {
                        i = (s->in_digit  &&  !hit)  ?  -99  :  lrintf(log10f(s->energy)*10.0f - DTMF_POWER_OFFSET + DBM0_MAX_POWER);
                        s->realtime_callback(s->realtime_callback_data, hit, i, 0);
                    }
                }
                else
                {
                    if (hit)
                    {
                        if (s->current_digits < MAX_DTMF_DIGITS)
                        {
                            s->digits[s->current_digits++] = (char) hit;
                            s->digits[s->current_digits] = '\0';
                            if (s->digits_callback)
                            {
                                s->digits_callback(s->digits_callback_data, s->digits, s->current_digits);
                                s->current_digits = 0;
                            }
                        }
                        else
                        {
                            s->lost_digits++;
                        }
                    }
                }
                s->in_digit = hit;
            }
        }
        s->last_hit = hit;
#if defined(SPANDSP_USE_FIXED_POINT)
        s->energy = 0;
#else
        s->energy = 0.0f;
#endif
        s->current_sample = 0;
    }
    if (s->current_digits  &&  s->digits_callback)
    {
        s->digits_callback(s->digits_callback_data, s->digits, s->current_digits);
        s->digits[0] = '\0';
        s->current_digits = 0;
    }
    return 0;
}
/*- End of function --------------------------------------------------------*/

int dtmf_rx_status(dtmf_rx_state_t *s)
{
    if (s->in_digit)
        return s->in_digit;
    if (s->last_hit)
        return 'x';
    return 0;
}
/*- End of function --------------------------------------------------------*/

size_t dtmf_rx_get(dtmf_rx_state_t *s, char *buf, int max)
{
    if (max > s->current_digits)
        max = s->current_digits;
    if (max > 0)
    {
        memcpy(buf, s->digits, max);
        memmove(s->digits, s->digits + max, s->current_digits - max);
        s->current_digits -= max;
    }
    buf[max] = '\0';
    return  max;
}
/*- End of function --------------------------------------------------------*/

void dtmf_rx_set_realtime_callback(dtmf_rx_state_t *s,
                                   tone_report_func_t callback,
                                   void *user_data)
{
    s->realtime_callback = callback;
    s->realtime_callback_data = user_data;
}
/*- End of function --------------------------------------------------------*/

void dtmf_rx_parms(dtmf_rx_state_t *s,
                   int filter_dialtone,
                   int twist,
                   int reverse_twist,
                   int threshold)
{
    float x;

    if (filter_dialtone >= 0)
    {
        s->z350[0] = 0.0f;
        s->z350[1] = 0.0f;
        s->z440[0] = 0.0f;
        s->z440[1] = 0.0f;
        s->filter_dialtone = filter_dialtone;
    }
    if (twist >= 0)
        s->normal_twist = powf(10.0f, twist/10.0f);
    if (reverse_twist >= 0)
        s->reverse_twist = powf(10.0f, reverse_twist/10.0f);
    if (threshold > -99)
    {
        x = (DTMF_SAMPLES_PER_BLOCK*32768.0f/1.4142f)*powf(10.0f, (threshold - DBM0_MAX_SINE_POWER)/20.0f);
        s->threshold = x*x;
    }
}
/*- End of function --------------------------------------------------------*/

dtmf_rx_state_t *dtmf_rx_init(dtmf_rx_state_t *s,
                              digits_rx_callback_t callback,
                              void *user_data)
{
    int i;
    static int initialised = FALSE;

    if (s == NULL)
    {
        if ((s = (dtmf_rx_state_t *) malloc(sizeof (*s))) == NULL)
            return  NULL;
    }
    s->digits_callback = callback;
    s->digits_callback_data = user_data;
    s->realtime_callback = NULL;
    s->realtime_callback_data = NULL;
    s->filter_dialtone = FALSE;
    s->normal_twist = DTMF_NORMAL_TWIST;
    s->reverse_twist = DTMF_REVERSE_TWIST;
    s->threshold = DTMF_THRESHOLD;

    s->in_digit = 0;
    s->last_hit = 0;

    if (!initialised)
    {
        for (i = 0;  i < 4;  i++)
        {
            make_goertzel_descriptor(&dtmf_detect_row[i], dtmf_row[i], DTMF_SAMPLES_PER_BLOCK);
            make_goertzel_descriptor(&dtmf_detect_col[i], dtmf_col[i], DTMF_SAMPLES_PER_BLOCK);
        }
        initialised = TRUE;
    }
    for (i = 0;  i < 4;  i++)
    {
        goertzel_init(&s->row_out[i], &dtmf_detect_row[i]);
        goertzel_init(&s->col_out[i], &dtmf_detect_col[i]);
    }
#if defined(SPANDSP_USE_FIXED_POINT)
    s->energy = 0;
#else
    s->energy = 0.0f;
#endif
    s->current_sample = 0;
    s->lost_digits = 0;
    s->current_digits = 0;
    s->digits[0] = '\0';
    return s;
}
/*- End of function --------------------------------------------------------*/

int dtmf_rx_free(dtmf_rx_state_t *s)
{
    free(s);
    return 0;
}
/*- End of function --------------------------------------------------------*/

static void dtmf_tx_initialise(void)
{
    int row;
    int col;

    if (dtmf_tx_inited)
        return;
    for (row = 0;  row < 4;  row++)
    {
        for (col = 0;  col < 4;  col++)
        {
            make_tone_gen_descriptor(&dtmf_digit_tones[row*4 + col],
                                     (int) dtmf_row[row],
                                     DEFAULT_DTMF_TX_LEVEL,
                                     (int) dtmf_col[col],
                                     DEFAULT_DTMF_TX_LEVEL,
                                     DEFAULT_DTMF_TX_ON_TIME,
                                     DEFAULT_DTMF_TX_OFF_TIME,
                                     0,
                                     0,
                                     FALSE);
        }
    }
    dtmf_tx_inited = TRUE;
}
/*- End of function --------------------------------------------------------*/

int dtmf_tx(dtmf_tx_state_t *s, int16_t amp[], int max_samples)
{
    int len;
    const char *cp;
    int digit;

    len = 0;
    if (s->tones.current_section >= 0)
    {
        /* Deal with the fragment left over from last time */
        len = tone_gen(&(s->tones), amp, max_samples);
    }
    while (len < max_samples  &&  (digit = queue_read_byte(&s->queue.queue)) >= 0)
    {
        /* Step to the next digit */
        if (digit == 0)
            continue;
        if ((cp = strchr(dtmf_positions, digit)) == NULL)
            continue;
        tone_gen_init(&(s->tones), &dtmf_digit_tones[cp - dtmf_positions]);
        s->tones.tone[0].gain = s->low_level;
        s->tones.tone[1].gain = s->high_level;
        s->tones.duration[0] = s->on_time;
        s->tones.duration[1] = s->off_time;
        len += tone_gen(&(s->tones), amp + len, max_samples - len);
    }
    return len;
}
/*- End of function --------------------------------------------------------*/

size_t dtmf_tx_put(dtmf_tx_state_t *s, const char *digits, int len)
{
    size_t space;

    /* This returns the number of characters that would not fit in the buffer.
       The buffer will only be loaded if the whole string of digits will fit,
       in which case zero is returned. */
    if (len < 0)
    {
        if ((len = strlen(digits)) == 0)
            return 0;
    }
    if ((space = queue_free_space(&s->queue.queue)) < len)
        return len - space;
    if (queue_write(&s->queue.queue, (const uint8_t *) digits, len) >= 0)
        return 0;
    return -1;
}
/*- End of function --------------------------------------------------------*/

void dtmf_tx_set_level(dtmf_tx_state_t *s, int level, int twist)
{
    s->low_level = dds_scaling_dbm0f((float) level);
    s->high_level = dds_scaling_dbm0f((float) (level + twist));
}
/*- End of function --------------------------------------------------------*/

void dtmf_tx_set_timing(dtmf_tx_state_t *s, int on_time, int off_time)
{
    s->on_time = ((on_time >= 0)  ?  on_time  :  DEFAULT_DTMF_TX_ON_TIME)*SAMPLE_RATE/1000;
    s->off_time = ((off_time >= 0)  ?  off_time  :  DEFAULT_DTMF_TX_OFF_TIME)*SAMPLE_RATE/1000;
}
/*- End of function --------------------------------------------------------*/

dtmf_tx_state_t *dtmf_tx_init(dtmf_tx_state_t *s)
{
    if (s == NULL)
    {
        if ((s = (dtmf_tx_state_t *) malloc(sizeof (*s))) == NULL)
            return  NULL;
    }
    if (!dtmf_tx_inited)
        dtmf_tx_initialise();
    tone_gen_init(&(s->tones), &dtmf_digit_tones[0]);
    dtmf_tx_set_level(s, DEFAULT_DTMF_TX_LEVEL, 0);
    dtmf_tx_set_timing(s, -1, -1);
    queue_init(&s->queue.queue, MAX_DTMF_DIGITS, QUEUE_READ_ATOMIC | QUEUE_WRITE_ATOMIC);
    s->tones.current_section = -1;
    return s;
}
/*- End of function --------------------------------------------------------*/

int dtmf_tx_free(dtmf_tx_state_t *s)
{
    free(s);
    return 0;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/