capidtmf.c

linux-2.6.15.6

#define CAPIDTMF_RECV_INDICATION_DIGIT        0x0001

static long capidtmf_recv_goertzel_coef_table[CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT] =
{
  0xda97L * 2,  /* 697 Hz (Low group 697 Hz) */
  0xd299L * 2,  /* 770 Hz (Low group 770 Hz) */
  0xc8cbL * 2,  /* 852 Hz (Low group 852 Hz) */
  0xbd36L * 2,  /* 941 Hz (Low group 941 Hz) */
  0x9501L * 2,  /* 1209 Hz (High group 1209 Hz) */
  0x7f89L * 2,  /* 1336 Hz (High group 1336 Hz) */
  0x6639L * 2,  /* 1477 Hz (High group 1477 Hz) */
  0x48c6L * 2,  /* 1633 Hz (High group 1633 Hz) */
  0xe14cL * 2,  /* 630 Hz (Lower guard of low group 631 Hz) */
  0xb2e0L * 2,  /* 1015 Hz (Upper guard of low group 1039 Hz) */
  0xa1a0L * 2,  /* 1130 Hz (Lower guard of high group 1140 Hz) */
  0x8a87L * 2,  /* 1272 Hz (Guard between 1209 Hz and 1336 Hz: 1271 Hz) */
  0x7353L * 2,  /* 1405 Hz (2nd harmonics of 697 Hz and guard between 1336 Hz and 1477 Hz: 1405 Hz) */
  0x583bL * 2,  /* 1552 Hz (2nd harmonics of 770 Hz and guard between 1477 Hz and 1633 Hz: 1553 Hz) */
  0x37d8L * 2,  /* 1720 Hz (2nd harmonics of 852 Hz and upper guard of high group: 1715 Hz) */
  0x0000L * 2   /* 100-630 Hz (fundamentals) */
};


static word capidtmf_recv_guard_snr_low_table[CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT] =
{
  14,                                    /* Low group peak versus 697 Hz */
  14,                                    /* Low group peak versus 770 Hz */
  16,                                    /* Low group peak versus 852 Hz */
  16,                                    /* Low group peak versus 941 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* Low group peak versus 1209 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* Low group peak versus 1336 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* Low group peak versus 1477 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* Low group peak versus 1633 Hz */
  14,                                    /* Low group peak versus 635 Hz */
  16,                                    /* Low group peak versus 1010 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* Low group peak versus 1140 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* Low group peak versus 1272 Hz */
  DSPDTMF_RX_HARMONICS_SEL_DEFAULT - 8,  /* Low group peak versus 1405 Hz */
  DSPDTMF_RX_HARMONICS_SEL_DEFAULT - 4,  /* Low group peak versus 1555 Hz */
  DSPDTMF_RX_HARMONICS_SEL_DEFAULT - 4,  /* Low group peak versus 1715 Hz */
  12                                     /* Low group peak versus 100-630 Hz */
};


static word capidtmf_recv_guard_snr_high_table[CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT] =
{
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* High group peak versus 697 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* High group peak versus 770 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* High group peak versus 852 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* High group peak versus 941 Hz */
  20,                                    /* High group peak versus 1209 Hz */
  20,                                    /* High group peak versus 1336 Hz */
  20,                                    /* High group peak versus 1477 Hz */
  20,                                    /* High group peak versus 1633 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* High group peak versus 635 Hz */
  CAPIDTMF_RECV_GUARD_SNR_DONTCARE,      /* High group peak versus 1010 Hz */
  16,                                    /* High group peak versus 1140 Hz */
  4,                                     /* High group peak versus 1272 Hz */
  6,                                     /* High group peak versus 1405 Hz */
  8,                                     /* High group peak versus 1555 Hz */
  16,                                    /* High group peak versus 1715 Hz */
  12                                     /* High group peak versus 100-630 Hz */
};


/*---------------------------------------------------------------------------*/

static void capidtmf_recv_init (t_capidtmf_state   *p_state)
{
  p_state->recv.min_gap_duration = 1;
  p_state->recv.min_digit_duration = 1;

  p_state->recv.cycle_counter = 0;
  p_state->recv.current_digit_on_time = 0;
  p_state->recv.current_digit_off_time = 0;
  p_state->recv.current_digit_value = CAPIDTMF_RECV_NO_DIGIT;

  p_state->recv.digit_write_pos = 0;
  p_state->recv.digit_read_pos = 0;
  p_state->recv.indication_state = 0;
  p_state->recv.indication_state_ack = 0;
  p_state->recv.state = CAPIDTMF_RECV_STATE_IDLE;
}


void capidtmf_recv_enable (t_capidtmf_state   *p_state, word min_digit_duration, word min_gap_duration)
{
  p_state->recv.indication_state_ack &= CAPIDTMF_RECV_INDICATION_DIGIT;
  p_state->recv.min_digit_duration = (word)(((((dword) min_digit_duration) * 8) +
    ((dword)(CAPIDTMF_RECV_TIME_GRANULARITY / 2))) / ((dword) CAPIDTMF_RECV_TIME_GRANULARITY));
  if (p_state->recv.min_digit_duration <= 1)
    p_state->recv.min_digit_duration = 1;
  else
    (p_state->recv.min_digit_duration)--;
  p_state->recv.min_gap_duration =
    (word)((((dword) min_gap_duration) * 8) / ((dword) CAPIDTMF_RECV_TIME_GRANULARITY));
  if (p_state->recv.min_gap_duration <= 1)
    p_state->recv.min_gap_duration = 1;
  else
    (p_state->recv.min_gap_duration)--;
  p_state->recv.state |= CAPIDTMF_RECV_STATE_DTMF_ACTIVE;
}


void capidtmf_recv_disable (t_capidtmf_state   *p_state)
{
  p_state->recv.state &= ~CAPIDTMF_RECV_STATE_DTMF_ACTIVE;
  if (p_state->recv.state == CAPIDTMF_RECV_STATE_IDLE)
    capidtmf_recv_init (p_state);
  else
  {
    p_state->recv.cycle_counter = 0;
    p_state->recv.current_digit_on_time = 0;
    p_state->recv.current_digit_off_time = 0;
    p_state->recv.current_digit_value = CAPIDTMF_RECV_NO_DIGIT;
  }
}


word capidtmf_recv_indication (t_capidtmf_state   *p_state, byte *buffer)
{
  word i, j, k, flags;

  flags = p_state->recv.indication_state ^ p_state->recv.indication_state_ack;
  p_state->recv.indication_state_ack ^= flags & CAPIDTMF_RECV_INDICATION_DIGIT;
  if (p_state->recv.digit_write_pos != p_state->recv.digit_read_pos)
  {
    i = 0;
    k = p_state->recv.digit_write_pos;
    j = p_state->recv.digit_read_pos;
    do
    {
      buffer[i++] = p_state->recv.digit_buffer[j];
      j = (j == CAPIDTMF_RECV_DIGIT_BUFFER_SIZE - 1) ? 0 : j + 1;
    } while (j != k);
    p_state->recv.digit_read_pos = k;
    return (i);
  }
  p_state->recv.indication_state_ack ^= flags;
  return (0);
}


#define CAPIDTMF_RECV_WINDOWED_SAMPLES  32

void capidtmf_recv_block (t_capidtmf_state   *p_state, byte   *buffer, word length)
{
  byte result_digit;
  word sample_number, cycle_counter, n, i;
  word low_peak, high_peak;
  dword lo, hi;
  byte   *p;
  short *q;
  byte goertzel_result_buffer[CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT];
    short windowed_sample_buffer[CAPIDTMF_RECV_WINDOWED_SAMPLES];


  if (p_state->recv.state & CAPIDTMF_RECV_STATE_DTMF_ACTIVE)
  {
    cycle_counter = p_state->recv.cycle_counter;
    sample_number = 0;
    while (sample_number < length)
    {
      if (cycle_counter < CAPIDTMF_RECV_ACCUMULATE_CYCLES)
      {
        if (cycle_counter == 0)
        {
          for (i = 0; i < CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT; i++)
          {
            p_state->recv.goertzel_buffer[0][i] = 0;
            p_state->recv.goertzel_buffer[1][i] = 0;
          }
        }
        n = CAPIDTMF_RECV_ACCUMULATE_CYCLES - cycle_counter;
        if (n > length - sample_number)
          n = length - sample_number;
        if (n > CAPIDTMF_RECV_WINDOWED_SAMPLES)
          n = CAPIDTMF_RECV_WINDOWED_SAMPLES;
        p = buffer + sample_number;
        q = capidtmf_recv_window_function + cycle_counter;
        if (p_state->ulaw)
        {
          for (i = 0; i < n; i++)
          {
            windowed_sample_buffer[i] =
              (short)((capidtmf_expand_table_ulaw[p[i]] * ((long)(q[i]))) >> 15);
	  }
        }
        else
        {
          for (i = 0; i < n; i++)
          {
            windowed_sample_buffer[i] =
              (short)((capidtmf_expand_table_alaw[p[i]] * ((long)(q[i]))) >> 15);
	  }
        }
        capidtmf_recv_goertzel_coef_table[CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT - 1] = CAPIDTMF_RECV_FUNDAMENTAL_OFFSET;
        capidtmf_goertzel_loop (p_state->recv.goertzel_buffer[0],
          capidtmf_recv_goertzel_coef_table, windowed_sample_buffer, n);
        cycle_counter += n;
        sample_number += n;
      }
      else
      {
        capidtmf_goertzel_result (p_state->recv.goertzel_buffer[0],
          capidtmf_recv_goertzel_coef_table);
        for (i = 0; i < CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT; i++)
        {
          lo = (dword)(p_state->recv.goertzel_buffer[0][i]);
          hi = (dword)(p_state->recv.goertzel_buffer[1][i]);
          if (hi != 0)
          {
            n = capidtmf_dword_leading_zeroes (hi);
            hi = (hi << n) | (lo >> (32 - n));
          }
          else
          {
            n = capidtmf_dword_leading_zeroes (lo);
            hi = lo << n;
	    n += 32;
          }
          n = 195 - 3 * n;
          if (hi >= 0xcb300000L)
            n += 2;
          else if (hi >= 0xa1450000L)
            n++;
	  goertzel_result_buffer[i] = (byte) n;
        }
        low_peak = DSPDTMF_RX_SENSITIVITY_LOW_DEFAULT;
        result_digit = CAPIDTMF_RECV_NO_DIGIT;
        for (i = 0; i < CAPIDTMF_LOW_GROUP_FREQUENCIES; i++)
        {
          if (goertzel_result_buffer[i] > low_peak)
	  {
	    low_peak = goertzel_result_buffer[i];
	    result_digit = (byte) i;
	  }
        }
        high_peak = DSPDTMF_RX_SENSITIVITY_HIGH_DEFAULT;
        n = CAPIDTMF_RECV_NO_DIGIT;
        for (i = CAPIDTMF_LOW_GROUP_FREQUENCIES; i < CAPIDTMF_RECV_BASE_FREQUENCY_COUNT; i++)
        {
          if (goertzel_result_buffer[i] > high_peak)
	  {
	    high_peak = goertzel_result_buffer[i];
	    n = (i - CAPIDTMF_LOW_GROUP_FREQUENCIES) << 2;
	  }
        }
        result_digit |= (byte) n;
        if (low_peak + DSPDTMF_RX_HIGH_EXCEEDING_LOW_DEFAULT < high_peak)
          result_digit = CAPIDTMF_RECV_NO_DIGIT;
        if (high_peak + DSPDTMF_RX_LOW_EXCEEDING_HIGH_DEFAULT < low_peak)
          result_digit = CAPIDTMF_RECV_NO_DIGIT;
        n = 0;
        for (i = 0; i < CAPIDTMF_RECV_TOTAL_FREQUENCY_COUNT; i++)
        {
          if ((((short)(low_peak - goertzel_result_buffer[i] - capidtmf_recv_guard_snr_low_table[i])) < 0)
           || (((short)(high_peak - goertzel_result_buffer[i] - capidtmf_recv_guard_snr_high_table[i])) < 0))
	  {
	    n++;
	  }
        }
        if (n != 2)
          result_digit = CAPIDTMF_RECV_NO_DIGIT;

        if (result_digit == CAPIDTMF_RECV_NO_DIGIT)
        {
          if (p_state->recv.current_digit_on_time != 0)
          {
            if (++(p_state->recv.current_digit_off_time) >= p_state->recv.min_gap_duration)
            {
              p_state->recv.current_digit_on_time = 0;
              p_state->recv.current_digit_off_time = 0;
            }
          }
          else
          {
            if (p_state->recv.current_digit_off_time != 0)
              (p_state->recv.current_digit_off_time)--;
          }
        }
        else
        {
          if ((p_state->recv.current_digit_on_time == 0)
           && (p_state->recv.current_digit_off_time != 0))
          {
            (p_state->recv.current_digit_off_time)--;
          }
          else
          {
            n = p_state->recv.current_digit_off_time;
            if ((p_state->recv.current_digit_on_time != 0)
             && (result_digit != p_state->recv.current_digit_value))
            {
              p_state->recv.current_digit_on_time = 0;
              n = 0;
            }
            p_state->recv.current_digit_value = result_digit;
            p_state->recv.current_digit_off_time = 0;
            if (p_state->recv.current_digit_on_time != 0xffff)
            {
              p_state->recv.current_digit_on_time += n + 1;
              if (p_state->recv.current_digit_on_time >= p_state->recv.min_digit_duration)
              {
                p_state->recv.current_digit_on_time = 0xffff;
                i = (p_state->recv.digit_write_pos == CAPIDTMF_RECV_DIGIT_BUFFER_SIZE - 1) ?
                  0 : p_state->recv.digit_write_pos + 1;
                if (i == p_state->recv.digit_read_pos)
                {
                  trace (dprintf ("%s,%d: Receive digit overrun",
                    (char   *)(FILE_), __LINE__));
                }
                else
                {
                  p_state->recv.digit_buffer[p_state->recv.digit_write_pos] = result_digit;
                  p_state->recv.digit_write_pos = i;
                  p_state->recv.indication_state =
                    (p_state->recv.indication_state & ~CAPIDTMF_RECV_INDICATION_DIGIT) |
                    (~p_state->recv.indication_state_ack & CAPIDTMF_RECV_INDICATION_DIGIT);
                }
              }
            }
          }
        }
        cycle_counter = 0;
        sample_number++;
      }
    }
    p_state->recv.cycle_counter = cycle_counter;
  }
}


void capidtmf_init (t_capidtmf_state   *p_state, byte ulaw)
{
  p_state->ulaw = ulaw;
  capidtmf_recv_init (p_state);
}


/*---------------------------------------------------------------------------*/