[net-next-2.6.git] / drivers / isdn / mISDN / dsp_ecdis.h

/*
 * SpanDSP - a series of DSP components for telephony
 *
 * ec_disable_detector.h - A detector which should eventually meet the
 *                         G.164/G.165 requirements for detecting the
 *                         2100Hz echo cancellor disable tone.
 *
 * Written by Steve Underwood <steveu@coppice.org>
 *
 * Copyright (C) 2001 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 as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 */

#include "dsp_biquad.h"

struct ec_disable_detector_state {
	struct biquad2_state notch;
	int notch_level;
	int channel_level;
	int tone_present;
	int tone_cycle_duration;
	int good_cycles;
	int hit;
};


#define FALSE 0
#define TRUE (!FALSE)

static inline void
echo_can_disable_detector_init(struct ec_disable_detector_state *det)
{
    /* Elliptic notch */
    /* This is actually centred at 2095Hz, but gets the balance we want, due
       to the asymmetric walls of the notch */
	biquad2_init(&det->notch,
		(int32_t) (-0.7600000*32768.0),
		(int32_t) (-0.1183852*32768.0),
		(int32_t) (-0.5104039*32768.0),
		(int32_t) (0.1567596*32768.0),
		(int32_t) (1.0000000*32768.0));

	det->channel_level = 0;
	det->notch_level = 0;
	det->tone_present = FALSE;
	det->tone_cycle_duration = 0;
	det->good_cycles = 0;
	det->hit = 0;
}
/*- End of function --------------------------------------------------------*/

static inline int
echo_can_disable_detector_update(struct ec_disable_detector_state *det,
int16_t amp)
{
	int16_t notched;

	notched = biquad2(&det->notch, amp);
	/* 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 */
	det->channel_level += ((abs(amp) - det->channel_level) >> 5);
	det->notch_level += ((abs(notched) - det->notch_level) >> 4);
	if (det->channel_level > 280) {
		/* There is adequate energy in the channel.
		 Is it mostly at 2100Hz? */
		if (det->notch_level*6 < det->channel_level) {
			/* The notch says yes, so we have the tone. */
			if (!det->tone_present) {
				/* Do we get a kick every 450+-25ms? */
				if (det->tone_cycle_duration >= 425*8
					&& det->tone_cycle_duration <= 475*8) {
					det->good_cycles++;
					if (det->good_cycles > 2)
						det->hit = TRUE;
				}
				det->tone_cycle_duration = 0;
			}
			det->tone_present = TRUE;
		} else
			det->tone_present = FALSE;
		det->tone_cycle_duration++;
	} else {
		det->tone_present = FALSE;
		det->tone_cycle_duration = 0;
		det->good_cycles = 0;
	}
	return det->hit;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/
Commit	Line	Data
960366cf KK	1	/*
	2	* SpanDSP - a series of DSP components for telephony
	3	*
	4	* ec_disable_detector.h - A detector which should eventually meet the
	5	* G.164/G.165 requirements for detecting the
	6	* 2100Hz echo cancellor disable tone.
	7	*
	8	* Written by Steve Underwood <steveu@coppice.org>
	9	*
	10	* Copyright (C) 2001 Steve Underwood
	11	*
	12	* All rights reserved.
	13	*
	14	* This program is free software; you can redistribute it and/or modify
	15	* it under the terms of the GNU General Public License as published by
	16	* the Free Software Foundation; either version 2 of the License, or
	17	* (at your option) any later version.
	18	*
	19	* This program is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	22	* GNU General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU General Public License
	25	* along with this program; if not, write to the Free Software
	26	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	27	*
	28	*/
	29
	30	#include "dsp_biquad.h"
	31
	32	struct ec_disable_detector_state {
	33	struct biquad2_state notch;
	34	int notch_level;
	35	int channel_level;
	36	int tone_present;
	37	int tone_cycle_duration;
	38	int good_cycles;
	39	int hit;
	40	};
	41
	42
	43	#define FALSE 0
	44	#define TRUE (!FALSE)
	45
	46	static inline void
	47	echo_can_disable_detector_init(struct ec_disable_detector_state *det)
	48	{
	49	/* Elliptic notch */
	50	/* This is actually centred at 2095Hz, but gets the balance we want, due
	51	to the asymmetric walls of the notch */
	52	biquad2_init(&det->notch,
	53	(int32_t) (-0.7600000*32768.0),
	54	(int32_t) (-0.1183852*32768.0),
	55	(int32_t) (-0.5104039*32768.0),
	56	(int32_t) (0.1567596*32768.0),
	57	(int32_t) (1.0000000*32768.0));
	58
	59	det->channel_level = 0;
	60	det->notch_level = 0;
	61	det->tone_present = FALSE;
	62	det->tone_cycle_duration = 0;
	63	det->good_cycles = 0;
	64	det->hit = 0;
65	}
66	/- End of function --------------------------------------------------------/
67
68	static inline int
69	echo_can_disable_detector_update(struct ec_disable_detector_state *det,
70	int16_t amp)
71	{
72	int16_t notched;
73
74	notched = biquad2(&det->notch, amp);
75	/* Estimate the overall energy in the channel, and the energy in
76	the notch (i.e. overall channel energy - tone energy => noise).
77	Use abs instead of multiply for speed (is it really faster?).
78	Damp the overall energy a little more for a stable result.
79	Damp the notch energy a little less, so we don't damp out the
80	blip every time the phase reverses */
81	det->channel_level += ((abs(amp) - det->channel_level) >> 5);
82	det->notch_level += ((abs(notched) - det->notch_level) >> 4);
83	if (det->channel_level > 280) {
84	/* There is adequate energy in the channel.
85	Is it mostly at 2100Hz? */
86	if (det->notch_level*6 < det->channel_level) {
87	/* The notch says yes, so we have the tone. */
88	if (!det->tone_present) {
89	/* Do we get a kick every 450+-25ms? */
90	if (det->tone_cycle_duration >= 425*8
91	&& det->tone_cycle_duration <= 475*8) {
92	det->good_cycles++;
93	if (det->good_cycles > 2)
eac74af9	94	det->hit = TRUE;
960366cf KK	95	}
	96	det->tone_cycle_duration = 0;
	97	}
	98	det->tone_present = TRUE;
	99	} else
	100	det->tone_present = FALSE;
	101	det->tone_cycle_duration++;
	102	} else {
	103	det->tone_present = FALSE;
	104	det->tone_cycle_duration = 0;
	105	det->good_cycles = 0;
	106	}
	107	return det->hit;
	108	}
	109	/- End of function --------------------------------------------------------/
	110	/- End of file ------------------------------------------------------------/