drivers/isdn/mISDN/dsp_dtmf.c - linux/kernel/git/viro/vfs - Git at Google

 /*
  * DTMF decoder.
  *
  * Copyright            by Andreas Eversberg (jolly@eversberg.eu)
  *			based on different decoders such as ISDN4Linux
  *
  * This software may be used and distributed according to the terms
  * of the GNU General Public License, incorporated herein by reference.
  *
  */

 #include <linux/mISDNif.h>
 #include <linux/mISDNdsp.h>
 #include "core.h"
 #include "dsp.h"

 #define NCOEFF            8     /* number of frequencies to be analyzed */

 /* For DTMF recognition:
  * 2 * cos(2 * PI * k / N) precalculated for all k
  */
 static u64 cos2pik[NCOEFF] =
 {
 	/* k << 15 (source: hfc-4s/8s documentation (www.colognechip.de)) */
 	55960, 53912, 51402, 48438, 38146, 32650, 26170, 18630
 };

 /* digit matrix */
 static char dtmf_matrix[4][4] =
 {
 	{'1', '2', '3', 'A'},
 	{'4', '5', '6', 'B'},
 	{'7', '8', '9', 'C'},
 	{'*', '0', '#', 'D'}
 };

 /* dtmf detection using goertzel algorithm
  * init function
  */
 void dsp_dtmf_goertzel_init(struct dsp *dsp)
 {
 	dsp->dtmf.size = 0;
 	dsp->dtmf.lastwhat = '\0';
 	dsp->dtmf.lastdigit = '\0';
 	dsp->dtmf.count = 0;
 }

 /* check for hardware or software features
  */
 void dsp_dtmf_hardware(struct dsp *dsp)
 {
 	int hardware = 1;

 	if (!dsp->dtmf.enable)
 		return;

 	if (!dsp->features.hfc_dtmf)
 		hardware = 0;

 	/* check for volume change */
 	if (dsp->tx_volume) {
 		if (dsp_debug & DEBUG_DSP_DTMF)
 			printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
 			       "because tx_volume is changed\n",
 			       __func__, dsp->name);
 		hardware = 0;
 	}
 	if (dsp->rx_volume) {
 		if (dsp_debug & DEBUG_DSP_DTMF)
 			printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
 			       "because rx_volume is changed\n",
 			       __func__, dsp->name);
 		hardware = 0;
 	}
 	/* check if encryption is enabled */
 	if (dsp->bf_enable) {
 		if (dsp_debug & DEBUG_DSP_DTMF)
 			printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
 			       "because encryption is enabled\n",
 			       __func__, dsp->name);
 		hardware = 0;
 	}
 	/* check if pipeline exists */
 	if (dsp->pipeline.inuse) {
 		if (dsp_debug & DEBUG_DSP_DTMF)
 			printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
 			       "because pipeline exists.\n",
 			       __func__, dsp->name);
 		hardware = 0;
 	}

 	dsp->dtmf.hardware = hardware;
 	dsp->dtmf.software = !hardware;
 }


 /*************************************************************
  * calculate the coefficients of the given sample and decode *
  *************************************************************/

 /* the given sample is decoded. if the sample is not long enough for a
  * complete frame, the decoding is finished and continued with the next
  * call of this function.
  *
  * the algorithm is very good for detection with a minimum of errors. i
  * tested it allot. it even works with very short tones (40ms). the only
  * disadvantage is, that it doesn't work good with different volumes of both
  * tones. this will happen, if accoustically coupled dialers are used.
  * it sometimes detects tones during speech, which is normal for decoders.
  * use sequences to given commands during calls.
  *
  * dtmf - points to a structure of the current dtmf state
  * spl and len - the sample
  * fmt - 0 = alaw, 1 = ulaw, 2 = coefficients from HFC DTMF hw-decoder
  */

 u8
 *dsp_dtmf_goertzel_decode(struct dsp *dsp, u8 *data, int len, int fmt)
 {
 	u8 what;
 	int size;
 	signed short *buf;
 	s32 sk, sk1, sk2;
 	int k, n, i;
 	s32 *hfccoeff;
 	s32 result[NCOEFF], tresh, treshl;
 	int lowgroup, highgroup;
 	s64 cos2pik_;

 	dsp->dtmf.digits[0] = '\0';

 	/* Note: The function will loop until the buffer has not enough samples
 	 * left to decode a full frame.
 	 */
 again:
 	/* convert samples */
 	size = dsp->dtmf.size;
 	buf = dsp->dtmf.buffer;
 	switch (fmt) {
 	case 0: /* alaw */
 	case 1: /* ulaw */
 		while (size < DSP_DTMF_NPOINTS && len) {
 			buf[size++] = dsp_audio_law_to_s32[*data++];
 			len--;
 		}
 		break;

 	case 2: /* HFC coefficients */
 	default:
 		if (len < 64) {
 			if (len > 0)
 				printk(KERN_ERR "%s: coefficients have invalid "
 				       "size. (is=%d < must=%d)\n",
 				       __func__, len, 64);
 			return dsp->dtmf.digits;
 		}
 		hfccoeff = (s32 *)data;
 		for (k = 0; k < NCOEFF; k++) {
 			sk2 = (*hfccoeff++) >> 4;
 			sk = (*hfccoeff++) >> 4;
 			if (sk > 32767 || sk < -32767 || sk2 > 32767
 			    || sk2 < -32767)
 				printk(KERN_WARNING
 				       "DTMF-Detection overflow\n");
 			/* compute |X(k)|**2 */
 			result[k] =
 				(sk * sk) -
 				(((cos2pik[k] * sk) >> 15) * sk2) +
 				(sk2 * sk2);
 		}
 		data += 64;
 		len -= 64;
 		goto coefficients;
 		break;
 	}
 	dsp->dtmf.size = size;

 	if (size < DSP_DTMF_NPOINTS)
 		return dsp->dtmf.digits;

 	dsp->dtmf.size = 0;

 	/* now we have a full buffer of signed long samples - we do goertzel */
 	for (k = 0; k < NCOEFF; k++) {
 		sk = 0;
 		sk1 = 0;
 		sk2 = 0;
 		buf = dsp->dtmf.buffer;
 		cos2pik_ = cos2pik[k];
 		for (n = 0; n < DSP_DTMF_NPOINTS; n++) {
 			sk = ((cos2pik_ * sk1) >> 15) - sk2 + (*buf++);
 			sk2 = sk1;
 			sk1 = sk;
 		}
 		sk >>= 8;
 		sk2 >>= 8;
 		if (sk > 32767 || sk < -32767 || sk2 > 32767 || sk2 < -32767)
 			printk(KERN_WARNING "DTMF-Detection overflow\n");
 		/* compute |X(k)|**2 */
 		result[k] =
 			(sk * sk) -
 			(((cos2pik[k] * sk) >> 15) * sk2) +
 			(sk2 * sk2);
 	}

 	/* our (squared) coefficients have been calculated, we need to process
 	 * them.
 	 */
 coefficients:
 	tresh = 0;
 	for (i = 0; i < NCOEFF; i++) {
 		if (result[i] < 0)
 			result[i] = 0;
 		if (result[i] > dsp->dtmf.treshold) {
 			if (result[i] > tresh)
 				tresh = result[i];
 		}
 	}

 	if (tresh == 0) {
 		what = 0;
 		goto storedigit;
 	}

 	if (dsp_debug & DEBUG_DSP_DTMFCOEFF) {
 		s32 tresh_100 = tresh/100;

 		if (tresh_100 == 0) {
 			tresh_100 = 1;
 			printk(KERN_DEBUG
 				"tresh(%d) too small set tresh/100 to 1\n",
 				tresh);
 		}
 		printk(KERN_DEBUG "a %3d %3d %3d %3d %3d %3d %3d %3d"
 		       " tr:%3d r %3d %3d %3d %3d %3d %3d %3d %3d\n",
 		       result[0] / 10000, result[1] / 10000, result[2] / 10000,
 		       result[3] / 10000, result[4] / 10000, result[5] / 10000,
 		       result[6] / 10000, result[7] / 10000, tresh / 10000,
 		       result[0] / (tresh_100), result[1] / (tresh_100),
 		       result[2] / (tresh_100), result[3] / (tresh_100),
 		       result[4] / (tresh_100), result[5] / (tresh_100),
 		       result[6] / (tresh_100), result[7] / (tresh_100));
 	}

 	/* calc digit (lowgroup/highgroup) */
 	lowgroup = -1;
 	highgroup = -1;
 	treshl = tresh >> 3;  /* tones which are not on, must be below 9 dB */
 	tresh = tresh >> 2;  /* touchtones must match within 6 dB */
 	for (i = 0; i < NCOEFF; i++) {
 		if (result[i] < treshl)
 			continue;  /* ignore */
 		if (result[i] < tresh) {
 			lowgroup = -1;
 			highgroup = -1;
 			break;  /* noise in between */
 		}
 		/* good level found. This is allowed only one time per group */
 		if (i < NCOEFF / 2) {
 			/* lowgroup */
 			if (lowgroup >= 0) {
 				/* Bad. Another tone found. */
 				lowgroup = -1;
 				break;
 			} else
 				lowgroup = i;
 		} else {
 			/* higroup */
 			if (highgroup >= 0) {
 				/* Bad. Another tone found. */
 				highgroup = -1;
 				break;
 			} else
 				highgroup = i - (NCOEFF / 2);
 		}
 	}

 	/* get digit or null */
 	what = 0;
 	if (lowgroup >= 0 && highgroup >= 0)
 		what = dtmf_matrix[lowgroup][highgroup];

 storedigit:
 	if (what && (dsp_debug & DEBUG_DSP_DTMF))
 		printk(KERN_DEBUG "DTMF what: %c\n", what);

 	if (dsp->dtmf.lastwhat != what)
 		dsp->dtmf.count = 0;

 	/* the tone (or no tone) must remain 3 times without change */
 	if (dsp->dtmf.count == 2) {
 		if (dsp->dtmf.lastdigit != what) {
 			dsp->dtmf.lastdigit = what;
 			if (what) {
 				if (dsp_debug & DEBUG_DSP_DTMF)
 					printk(KERN_DEBUG "DTMF digit: %c\n",
 					       what);
 				if ((strlen(dsp->dtmf.digits) + 1)
 				    < sizeof(dsp->dtmf.digits)) {
 					dsp->dtmf.digits[strlen(
 							dsp->dtmf.digits) + 1] = '\0';
 					dsp->dtmf.digits[strlen(
 							dsp->dtmf.digits)] = what;
 				}
 			}
 		}
 	} else
 		dsp->dtmf.count++;

 	dsp->dtmf.lastwhat = what;

 	goto again;
 }
	/*
	* DTMF decoder.
	*
	* Copyright by Andreas Eversberg (jolly@eversberg.eu)
	* based on different decoders such as ISDN4Linux
	*
	* This software may be used and distributed according to the terms
	* of the GNU General Public License, incorporated herein by reference.
	*
	*/

	#include <linux/mISDNif.h>
	#include <linux/mISDNdsp.h>
	#include "core.h"
	#include "dsp.h"

	#define NCOEFF 8 /* number of frequencies to be analyzed */

	/* For DTMF recognition:
	* 2 * cos(2 * PI * k / N) precalculated for all k
	*/
	static u64 cos2pik[NCOEFF] =
	{
	/* k << 15 (source: hfc-4s/8s documentation (www.colognechip.de)) */
	55960, 53912, 51402, 48438, 38146, 32650, 26170, 18630
	};

	/* digit matrix */
	static char dtmf_matrix[4][4] =
	{
	{'1', '2', '3', 'A'},
	{'4', '5', '6', 'B'},
	{'7', '8', '9', 'C'},
	{'*', '0', '#', 'D'}
	};

	/* dtmf detection using goertzel algorithm
	* init function
	*/
	void dsp_dtmf_goertzel_init(struct dsp *dsp)
	{
	dsp->dtmf.size = 0;
	dsp->dtmf.lastwhat = '\0';
	dsp->dtmf.lastdigit = '\0';
	dsp->dtmf.count = 0;
	}

	/* check for hardware or software features
	*/
	void dsp_dtmf_hardware(struct dsp *dsp)
	{
	int hardware = 1;

	if (!dsp->dtmf.enable)
	return;

	if (!dsp->features.hfc_dtmf)
	hardware = 0;

	/* check for volume change */
	if (dsp->tx_volume) {
	if (dsp_debug & DEBUG_DSP_DTMF)
	printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
	"because tx_volume is changed\n",
	__func__, dsp->name);
	hardware = 0;
	}
	if (dsp->rx_volume) {
	if (dsp_debug & DEBUG_DSP_DTMF)
	printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
	"because rx_volume is changed\n",
	__func__, dsp->name);
	hardware = 0;
	}
	/* check if encryption is enabled */
	if (dsp->bf_enable) {
	if (dsp_debug & DEBUG_DSP_DTMF)
	printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
	"because encryption is enabled\n",
	__func__, dsp->name);
	hardware = 0;
	}
	/* check if pipeline exists */
	if (dsp->pipeline.inuse) {
	if (dsp_debug & DEBUG_DSP_DTMF)
	printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "
	"because pipeline exists.\n",
	__func__, dsp->name);
	hardware = 0;
	}

	dsp->dtmf.hardware = hardware;
	dsp->dtmf.software = !hardware;
	}


	/*************************************************************
	* calculate the coefficients of the given sample and decode *
	*************************************************************/

	/* the given sample is decoded. if the sample is not long enough for a
	* complete frame, the decoding is finished and continued with the next
	* call of this function.
	*
	* the algorithm is very good for detection with a minimum of errors. i
	* tested it allot. it even works with very short tones (40ms). the only
	* disadvantage is, that it doesn't work good with different volumes of both
	* tones. this will happen, if accoustically coupled dialers are used.
	* it sometimes detects tones during speech, which is normal for decoders.
	* use sequences to given commands during calls.
	*
	* dtmf - points to a structure of the current dtmf state
	* spl and len - the sample
	* fmt - 0 = alaw, 1 = ulaw, 2 = coefficients from HFC DTMF hw-decoder
	*/

	u8
	dsp_dtmf_goertzel_decode(struct dsp dsp, u8 *data, int len, int fmt)
	{
	u8 what;
	int size;
	signed short *buf;
	s32 sk, sk1, sk2;
	int k, n, i;
	s32 *hfccoeff;
	s32 result[NCOEFF], tresh, treshl;
	int lowgroup, highgroup;
	s64 cos2pik_;

	dsp->dtmf.digits[0] = '\0';

	/* Note: The function will loop until the buffer has not enough samples
	* left to decode a full frame.
	*/
	again:
	/* convert samples */
	size = dsp->dtmf.size;
	buf = dsp->dtmf.buffer;
	switch (fmt) {
	case 0: /* alaw */
	case 1: /* ulaw */
	while (size < DSP_DTMF_NPOINTS && len) {
	buf[size++] = dsp_audio_law_to_s32[*data++];
	len--;
	}
	break;

	case 2: /* HFC coefficients */
	default:
	if (len < 64) {
	if (len > 0)
	printk(KERN_ERR "%s: coefficients have invalid "
	"size. (is=%d < must=%d)\n",
	__func__, len, 64);
	return dsp->dtmf.digits;
	}
	hfccoeff = (s32 *)data;
	for (k = 0; k < NCOEFF; k++) {
	sk2 = (*hfccoeff++) >> 4;
	sk = (*hfccoeff++) >> 4;
	if (sk > 32767 \|\| sk < -32767 \|\| sk2 > 32767
	\|\| sk2 < -32767)
	printk(KERN_WARNING
	"DTMF-Detection overflow\n");
	/* compute \|X(k)\|*2 /
	result[k] =
	(sk * sk) -
	(((cos2pik[k] * sk) >> 15) * sk2) +
	(sk2 * sk2);
	}
	data += 64;
	len -= 64;
	goto coefficients;
	break;
	}
	dsp->dtmf.size = size;

	if (size < DSP_DTMF_NPOINTS)
	return dsp->dtmf.digits;

	dsp->dtmf.size = 0;

	/* now we have a full buffer of signed long samples - we do goertzel */
	for (k = 0; k < NCOEFF; k++) {
	sk = 0;
	sk1 = 0;
	sk2 = 0;
	buf = dsp->dtmf.buffer;
	cos2pik_ = cos2pik[k];
	for (n = 0; n < DSP_DTMF_NPOINTS; n++) {
	sk = ((cos2pik_ * sk1) >> 15) - sk2 + (*buf++);
	sk2 = sk1;
	sk1 = sk;
	}
	sk >>= 8;
	sk2 >>= 8;
	if (sk > 32767 \|\| sk < -32767 \|\| sk2 > 32767 \|\| sk2 < -32767)
	printk(KERN_WARNING "DTMF-Detection overflow\n");
	/* compute \|X(k)\|*2 /
	result[k] =
	(sk * sk) -
	(((cos2pik[k] * sk) >> 15) * sk2) +
	(sk2 * sk2);
	}

	/* our (squared) coefficients have been calculated, we need to process
	* them.
	*/
	coefficients:
	tresh = 0;
	for (i = 0; i < NCOEFF; i++) {
	if (result[i] < 0)
	result[i] = 0;
	if (result[i] > dsp->dtmf.treshold) {
	if (result[i] > tresh)
	tresh = result[i];
	}
	}

	if (tresh == 0) {
	what = 0;
	goto storedigit;
	}

	if (dsp_debug & DEBUG_DSP_DTMFCOEFF) {
	s32 tresh_100 = tresh/100;

	if (tresh_100 == 0) {
	tresh_100 = 1;
	printk(KERN_DEBUG
	"tresh(%d) too small set tresh/100 to 1\n",
	tresh);
	}
	printk(KERN_DEBUG "a %3d %3d %3d %3d %3d %3d %3d %3d"
	" tr:%3d r %3d %3d %3d %3d %3d %3d %3d %3d\n",
	result[0] / 10000, result[1] / 10000, result[2] / 10000,
	result[3] / 10000, result[4] / 10000, result[5] / 10000,
	result[6] / 10000, result[7] / 10000, tresh / 10000,
	result[0] / (tresh_100), result[1] / (tresh_100),
	result[2] / (tresh_100), result[3] / (tresh_100),
	result[4] / (tresh_100), result[5] / (tresh_100),
	result[6] / (tresh_100), result[7] / (tresh_100));
	}

	/* calc digit (lowgroup/highgroup) */
	lowgroup = -1;
	highgroup = -1;
	treshl = tresh >> 3; /* tones which are not on, must be below 9 dB */
	tresh = tresh >> 2; /* touchtones must match within 6 dB */
	for (i = 0; i < NCOEFF; i++) {
	if (result[i] < treshl)
	continue; /* ignore */
	if (result[i] < tresh) {
	lowgroup = -1;
	highgroup = -1;
	break; /* noise in between */
	}
	/* good level found. This is allowed only one time per group */
	if (i < NCOEFF / 2) {
	/* lowgroup */
	if (lowgroup >= 0) {
	/* Bad. Another tone found. */
	lowgroup = -1;
	break;
	} else
	lowgroup = i;
	} else {
	/* higroup */
	if (highgroup >= 0) {
	/* Bad. Another tone found. */
	highgroup = -1;
	break;
	} else
	highgroup = i - (NCOEFF / 2);
	}
	}

	/* get digit or null */
	what = 0;
	if (lowgroup >= 0 && highgroup >= 0)
	what = dtmf_matrix[lowgroup][highgroup];

	storedigit:
	if (what && (dsp_debug & DEBUG_DSP_DTMF))
	printk(KERN_DEBUG "DTMF what: %c\n", what);

	if (dsp->dtmf.lastwhat != what)
	dsp->dtmf.count = 0;

	/* the tone (or no tone) must remain 3 times without change */
	if (dsp->dtmf.count == 2) {
	if (dsp->dtmf.lastdigit != what) {
	dsp->dtmf.lastdigit = what;
	if (what) {
	if (dsp_debug & DEBUG_DSP_DTMF)
	printk(KERN_DEBUG "DTMF digit: %c\n",
	what);
	if ((strlen(dsp->dtmf.digits) + 1)
	< sizeof(dsp->dtmf.digits)) {
	dsp->dtmf.digits[strlen(
	dsp->dtmf.digits) + 1] = '\0';
	dsp->dtmf.digits[strlen(
	dsp->dtmf.digits)] = what;
	}
	}
	}
	} else
	dsp->dtmf.count++;

	dsp->dtmf.lastwhat = what;

	goto again;
	}