isdn_audio.c

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		s->a = 0;
		s->d = 5;
		s->word = 0;
		s->nleft = 0;
		s->nbits = nbits;
	}
	return s;
}

dtmf_state *
isdn_audio_dtmf_init(dtmf_state * s)
{
	if (!s)
		s = (dtmf_state *) kmalloc(sizeof(dtmf_state), GFP_ATOMIC);
	if (s) {
		s->idx = 0;
		s->last = ' ';
	}
	return s;
}

/*
 * Decompression of adpcm data to a/u-law
 *
 */

int
isdn_audio_adpcm2xlaw(adpcm_state * s, int fmt, unsigned char *in,
		      unsigned char *out, int len)
{
	int a = s->a;
	int d = s->d;
	int nbits = s->nbits;
	int olen = 0;

	while (len) {
		int e = isdn_audio_get_bits(s, &in, &len);
		int sign;

		if (nbits == 4 && e == 0)
			d = 4;
		sign = (e >> (nbits - 1)) ? -1 : 1;
		e &= bitmask[nbits - 1];
		a += sign * ((e << 1) + 1) * d >> 1;
		if (d & 1)
			a++;
		if (fmt)
			*out++ = isdn_audio_ulaw_to_alaw[
					 isdn_audio_linear2ulaw(a << 2)];
		else
			*out++ = isdn_audio_linear2ulaw(a << 2);
		olen++;
		d = (d * Mx[nbits - 2][e] + 0x2000) >> 14;
		if (d < 5)
			d = 5;
	}
	s->a = a;
	s->d = d;
	return olen;
}

int
isdn_audio_2adpcm_flush(adpcm_state * s, unsigned char *out)
{
	int olen = 0;

	if (s->nleft)
		isdn_audio_put_bits(0, 8 - s->nleft, s, &out, &olen);
	return olen;
}

int
isdn_audio_xlaw2adpcm(adpcm_state * s, int fmt, unsigned char *in,
		      unsigned char *out, int len)
{
	int a = s->a;
	int d = s->d;
	int nbits = s->nbits;
	int olen = 0;

	while (len--) {
		int e = 0,
		 nmax = 1 << (nbits - 1);
		int sign,
		 delta;

		if (fmt)
			delta = (isdn_audio_alaw_to_s16[*in++] >> 2) - a;
		else
			delta = (isdn_audio_ulaw_to_s16[*in++] >> 2) - a;
		if (delta < 0) {
			e = nmax;
			delta = -delta;
		}
		while (--nmax && delta > d) {
			delta -= d;
			e++;
		}
		if (nbits == 4 && ((e & 0x0f) == 0))
			e = 8;
		isdn_audio_put_bits(e, nbits, s, &out, &olen);
		sign = (e >> (nbits - 1)) ? -1 : 1;
		e &= bitmask[nbits - 1];

		a += sign * ((e << 1) + 1) * d >> 1;
		if (d & 1)
			a++;
		d = (d * Mx[nbits - 2][e] + 0x2000) >> 14;
		if (d < 5)
			d = 5;
	}
	s->a = a;
	s->d = d;
	return olen;
}

/*
 * Goertzel algorithm.
 * See http://ptolemy.eecs.berkeley.edu/~pino/Ptolemy/papers/96/dtmf_ict/
 * for more info.
 * Result is stored into an sk_buff and queued up for later
 * evaluation.
 */
static void
isdn_audio_goertzel(int *sample, modem_info * info)
{
	int sk,
	 sk1,
	 sk2;
	int k,
	 n;
	struct sk_buff *skb;
	int *result;

	skb = dev_alloc_skb(sizeof(int) * NCOEFF);
	if (!skb) {
		printk(KERN_WARNING
		  "isdn_audio: Could not alloc DTMF result for ttyI%d\n",
		       info->line);
		return;
	}
	result = (int *) skb_put(skb, sizeof(int) * NCOEFF);
	for (k = 0; k < NCOEFF; k++) {
		sk = sk1 = sk2 = 0;
		for (n = 0; n < DTMF_NPOINTS; n++) {
			sk = sample[n] + ((cos2pik[k] * sk1) >> 15) - sk2;
			sk2 = sk1;
			sk1 = sk;
		}
		result[k] =
		    ((sk * sk) >> AMP_BITS) -
		    ((((cos2pik[k] * sk) >> 15) * sk2) >> AMP_BITS) +
		    ((sk2 * sk2) >> AMP_BITS);
	}
	skb_queue_tail(&info->dtmf_queue, skb);
	isdn_timer_ctrl(ISDN_TIMER_MODEMREAD, 1);
}

void
isdn_audio_eval_dtmf(modem_info * info)
{
	struct sk_buff *skb;
	int *result;
	dtmf_state *s;
	int silence;
	int i;
	int di;
	int ch;
	unsigned long flags;
	int grp[2];
	char what;
	char *p;

	while ((skb = skb_dequeue(&info->dtmf_queue))) {
		result = (int *) skb->data;
		s = info->dtmf_state;
		grp[LOGRP] = grp[HIGRP] = -2;
		silence = 0;
		for (i = 0; i < 8; i++) {
			if ((result[dtmf_tones[i].k] > DTMF_TRESH) &&
			    (result[dtmf_tones[i].k2] < H2_TRESH))
				grp[dtmf_tones[i].grp] = (grp[dtmf_tones[i].grp] == -2) ? i : -1;
			else if ((result[dtmf_tones[i].k] < SILENCE_TRESH) &&
			      (result[dtmf_tones[i].k2] < SILENCE_TRESH))
				silence++;
		}
		if (silence == 8)
			what = ' ';
		else {
			if ((grp[LOGRP] >= 0) && (grp[HIGRP] >= 0)) {
				what = dtmf_matrix[grp[LOGRP]][grp[HIGRP] - 4];
				if (s->last != ' ' && s->last != '.')
					s->last = what;	/* min. 1 non-DTMF between DTMF */
			} else
				what = '.';
		}
		if ((what != s->last) && (what != ' ') && (what != '.')) {
			printk(KERN_DEBUG "dtmf: tt='%c'\n", what);
			p = skb->data;
			*p++ = 0x10;
			*p = what;
			skb_trim(skb, 2);
			if (skb_headroom(skb) < sizeof(isdn_audio_skb)) {
				printk(KERN_WARNING
				       "isdn_audio: insufficient skb_headroom, dropping\n");
				kfree_skb(skb);
				return;
			}
			ISDN_AUDIO_SKB_DLECOUNT(skb) = 0;
			ISDN_AUDIO_SKB_LOCK(skb) = 0;
			save_flags(flags);
			cli();
			di = info->isdn_driver;
			ch = info->isdn_channel;
			__skb_queue_tail(&dev->drv[di]->rpqueue[ch], skb);
			dev->drv[di]->rcvcount[ch] += 2;
			restore_flags(flags);
			/* Schedule dequeuing */
			if ((dev->modempoll) && (info->rcvsched))
				isdn_timer_ctrl(ISDN_TIMER_MODEMREAD, 1);
			wake_up_interruptible(&dev->drv[di]->rcv_waitq[ch]);
		} else
			kfree_skb(skb);
		s->last = what;
	}
}

/*
 * Decode DTMF tones, queue result in separate sk_buf for
 * later examination.
 * Parameters:
 *   s    = pointer to state-struct.
 *   buf  = input audio data
 *   len  = size of audio data.
 *   fmt  = audio data format (0 = ulaw, 1 = alaw)
 */
void
isdn_audio_calc_dtmf(modem_info * info, unsigned char *buf, int len, int fmt)
{
	dtmf_state *s = info->dtmf_state;
	int i;
	int c;

	while (len) {
		c = MIN(len, (DTMF_NPOINTS - s->idx));
		if (c <= 0)
			break;
		for (i = 0; i < c; i++) {
			if (fmt)
				s->buf[s->idx++] =
				    isdn_audio_alaw_to_s16[*buf++] >> (15 - AMP_BITS);
			else
				s->buf[s->idx++] =
				    isdn_audio_ulaw_to_s16[*buf++] >> (15 - AMP_BITS);
		}
		if (s->idx == DTMF_NPOINTS) {
			isdn_audio_goertzel(s->buf, info);
			s->idx = 0;
		}
		len -= c;
	}
}

silence_state *
isdn_audio_silence_init(silence_state * s)
{
	if (!s)
		s = (silence_state *) kmalloc(sizeof(silence_state), GFP_ATOMIC);
	if (s) {
		s->idx = 0;
		s->state = 0;
	}
	return s;
}

void
isdn_audio_calc_silence(modem_info * info, unsigned char *buf, int len, int fmt)
{
	silence_state *s = info->silence_state;
	int i;
	signed char c;

	if (!info->emu.vpar[1]) return;

	for (i = 0; i < len; i++) {
		if (fmt)
		    c = isdn_audio_alaw_to_ulaw[*buf++];
			else
		    c = *buf++;

		if (c > 0) c -= 128;
		c = abs(c);

		if (c > (info->emu.vpar[1] * 4)) { 
			s->idx = 0;
			s->state = 1; 
		} else {
			if (s->idx < 210000) s->idx++; 
		}
	}
}

void
isdn_audio_put_dle_code(modem_info * info, u_char code)
{
	struct sk_buff *skb;
	unsigned long flags;
	int di;
	int ch;
	char *p;

	skb = dev_alloc_skb(2);
	if (!skb) {
		printk(KERN_WARNING
		  "isdn_audio: Could not alloc skb for ttyI%d\n",
		       info->line);
		return;
	}
	p = (char *) skb_put(skb, 2);
	p[0] = 0x10;
	p[1] = code;
	if (skb_headroom(skb) < sizeof(isdn_audio_skb)) {
		printk(KERN_WARNING
		       "isdn_audio: insufficient skb_headroom, dropping\n");
		kfree_skb(skb);
		return;
	}
	ISDN_AUDIO_SKB_DLECOUNT(skb) = 0;
	ISDN_AUDIO_SKB_LOCK(skb) = 0;
	save_flags(flags);
	cli();
	di = info->isdn_driver;
	ch = info->isdn_channel;
	__skb_queue_tail(&dev->drv[di]->rpqueue[ch], skb);
	dev->drv[di]->rcvcount[ch] += 2;
	restore_flags(flags);
	/* Schedule dequeuing */
	if ((dev->modempoll) && (info->rcvsched))
		isdn_timer_ctrl(ISDN_TIMER_MODEMREAD, 1);
	wake_up_interruptible(&dev->drv[di]->rcv_waitq[ch]);
}

void
isdn_audio_eval_silence(modem_info * info)
{
	silence_state *s = info->silence_state;
	char what;

	what = ' ';

	if (s->idx > (info->emu.vpar[2] * 800)) { 
		s->idx = 0;
		if (!s->state) {	/* silence from beginning of rec */ 
			what = 's';
		} else {
			what = 'q';
		}
	}
		if ((what == 's') || (what == 'q')) {
			printk(KERN_DEBUG "ttyI%d: %s\n", info->line,
				(what=='s') ? "silence":"quiet");
			isdn_audio_put_dle_code(info, what);
		} 
}