merge modular_ec branch, which adds modular echocan support and lots of minor fixes and improvements... seems to work properly, except the usecount on the echocan modules never increments above zero, so they are unloadable when they should not be

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@4436 a0bf4364-ded3-4de4-8d8a-66a801d63aff

1 files changed, 337 insertions, 0 deletions

diff --git a/drivers/dahdi/dahdi_echocan_sec.c b/drivers/dahdi/dahdi_echocan_sec.c
new file mode 100644
index 0000000..dd0a7f4
--- /dev/null
+++ b/drivers/dahdi/dahdi_echocan_sec.c
@@ -0,0 +1,337 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * echo.c - An echo cancellor, suitable for electrical and acoustic
+ *	    cancellation. This code does not currently comply with
+ *	    any relevant standards (e.g. G.164/5/7/8). One day....
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ * Various optimizations and improvements by Mark Spencer <markster@digium.com>
+ *
+ * Copyright (C) 2001 Steve Underwood
+ *
+ * Based on a bit from here, a bit from there, eye of toad,
+ * ear of bat, etc - plus, of course, my own 2 cents.
+ *
+ * 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.
+ *
+ */
+
+/* TODO:
+   Finish the echo suppressor option, however nasty suppression may be
+   Add an option to reintroduce side tone at -24dB under appropriate conditions.
+   Improve double talk detector (iterative!)
+*/
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/ctype.h>
+#include <linux/moduleparam.h>
+
+#include <dahdi/kernel.h>
+
+static int debug;
+
+#define module_printk(level, fmt, args...) printk(level "%s: " fmt, THIS_MODULE->name, ## args)
+#define debug_printk(level, fmt, args...) if (debug >= level) printk("%s (%s): " fmt, THIS_MODULE->name, __FUNCTION__, ## args)
+
+#include "arith.h"
+
+#ifndef NULL
+#define NULL 0
+#endif
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE (!FALSE)
+#endif
+
+#define USE_SHORTS
+
+#define NONUPDATE_DWELL_TIME	600 	/* 600 samples, or 75ms */
+
+struct echo_can_state
+{
+    int tx_power;
+    int rx_power;
+    int clean_rx_power;
+
+    int rx_power_threshold;
+    int nonupdate_dwell;
+
+    int16_t *tx_history;	/* Last N tx samples */
+    int32_t *fir_taps;	    	/* Echo FIR taps */
+	int16_t *fir_taps_short;	/* Echo FIR taps, shorts instead of ints */
+
+    int curr_pos;
+	
+    int taps;
+    int tap_mask;
+    int use_nlp;
+    int use_suppressor;
+    
+    int32_t supp_test1;
+    int32_t supp_test2;
+    int32_t supp1;
+    int32_t supp2;
+
+    int32_t latest_correction;  /* Indication of the magnitude of the latest
+    				   adaption, or a code to indicate why adaption
+				   was skipped, for test purposes */
+};
+
+/* Original parameters : 
+#define MIN_TX_POWER_FOR_ADAPTION   256
+#define MIN_RX_POWER_FOR_ADAPTION   128
+*/
+
+#define MIN_TX_POWER_FOR_ADAPTION   256
+#define MIN_RX_POWER_FOR_ADAPTION   64
+
+/* Better ones found by Jim 
+#define MIN_TX_POWER_FOR_ADAPTION   128
+#define MIN_RX_POWER_FOR_ADAPTION   64
+*/
+
+static int echo_can_create(struct dahdi_echocanparams *ecp, struct dahdi_echocanparam *p,
+			   struct echo_can_state **ec)
+{
+	size_t size;
+	
+	if (ecp->param_count > 0) {
+		printk(KERN_WARNING "SEC echo canceler does not support parameters; failing request\n");
+		return -EINVAL;
+	}
+	
+	size = sizeof(**ec) + ecp->tap_length * sizeof(int32_t) + ecp->tap_length * 3 * sizeof(int16_t);
+	
+	if (!(*ec = kmalloc(size, GFP_KERNEL)))
+		return -ENOMEM;
+	
+	memset(*ec, 0, size);
+
+	(*ec)->taps = ecp->tap_length;
+	(*ec)->tap_mask = ecp->tap_length - 1;
+	(*ec)->tx_history = (int16_t *) (*ec + sizeof(**ec));
+	(*ec)->fir_taps = (int32_t *) (*ec + sizeof(**ec) +
+				       ecp->tap_length * 2 * sizeof(int16_t));
+	(*ec)->fir_taps_short = (int16_t *) (*ec + sizeof(**ec) +
+					     ecp->tap_length * sizeof(int32_t) +
+					     ecp->tap_length * 2 * sizeof(int16_t));
+	(*ec)->rx_power_threshold = 10000000;
+	(*ec)->use_suppressor = FALSE;
+	/* Non-linear processor - a fancy way to say "zap small signals, to avoid
+	   accumulating noise". */
+	(*ec)->use_nlp = TRUE;
+
+	return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+static void echo_can_free(struct echo_can_state *ec)
+{
+	kfree(ec);
+}
+/*- End of function --------------------------------------------------------*/
+
+static inline int16_t sample_update(struct echo_can_state *ec, int16_t tx, int16_t rx)
+{
+    int32_t echo_value;
+    int clean_rx;
+    int nsuppr;
+
+    ec->tx_history[ec->curr_pos] = tx;
+    ec->tx_history[ec->curr_pos + ec->taps] = tx;
+
+    /* Evaluate the echo - i.e. apply the FIR filter */
+    /* Assume the gain of the FIR does not exceed unity. Exceeding unity
+       would seem like a rather poor thing for an echo cancellor to do :)
+       This means we can compute the result with a total disregard for
+       overflows. 16bits x 16bits -> 31bits, so no overflow can occur in
+       any multiply. While accumulating we may overflow and underflow the
+       32 bit scale often. However, if the gain does not exceed unity,
+       everything should work itself out, and the final result will be
+       OK, without any saturation logic. */
+    /* Overflow is very much possible here, and we do nothing about it because
+       of the compute costs */
+    /* 16 bit coeffs for the LMS give lousy results (maths good, actual sound
+       bad!), but 32 bit coeffs require some shifting. On balance 32 bit seems
+       best */
+#ifdef USE_SHORTS
+    echo_value = CONVOLVE2(ec->fir_taps_short, ec->tx_history + ec->curr_pos, ec->taps);
+#else
+    echo_value = CONVOLVE(ec->fir_taps, ec->tx_history + ec->curr_pos, ec->taps);
+#endif
+    echo_value >>= 16;
+
+    /* And the answer is..... */
+    clean_rx = rx - echo_value;
+
+    /* That was the easy part. Now we need to adapt! */
+    if (ec->nonupdate_dwell > 0)
+    	ec->nonupdate_dwell--;
+
+    /* If there is very little being transmitted, any attempt to train is
+       futile. We would either be training on the far end's noise or signal,
+       the channel's own noise, or our noise. Either way, this is hardly good
+       training, so don't do it (avoid trouble). */
+    /* If the received power is very low, either we are sending very little or
+       we are already well adapted. There is little point in trying to improve
+       the adaption under these circumstanceson, so don't do it (reduce the
+       compute load). */
+    if (ec->tx_power > MIN_TX_POWER_FOR_ADAPTION
+    	&&
+	ec->rx_power > MIN_RX_POWER_FOR_ADAPTION)
+    {
+    	/* This is a really crude piece of decision logic, but it does OK
+	   for now. */
+    	if (ec->tx_power > ec->rx_power << 1)
+	{
+            /* There is no far-end speech detected */
+            if (ec->nonupdate_dwell == 0)
+	    {
+	    	/* ... and we are not in the dwell time from previous speech. */
+		//nsuppr = saturate((clean_rx << 16)/ec->tx_power);
+		nsuppr = (clean_rx << 16) / ec->tx_power;
+		nsuppr >>= 4;
+		if (nsuppr > 512)
+			nsuppr = 512;
+		if (nsuppr < -512)
+			nsuppr = -512;
+
+		/* Update the FIR taps */
+		ec->latest_correction = 0;
+#ifdef USE_SHORTS
+		UPDATE2(ec->fir_taps, ec->fir_taps_short, ec->tx_history + ec->curr_pos, nsuppr, ec->taps);
+#else				
+		UPDATE(ec->fir_taps, ec->fir_taps_short, ec->tx_history + ec->curr_pos, nsuppr, ec->taps);
+#endif		
+	   }  else
+	    {
+        	ec->latest_correction = -3;
+    	    }
+	}
+	else
+	{
+            ec->nonupdate_dwell = NONUPDATE_DWELL_TIME;
+    	    ec->latest_correction = -2;
+	}
+    }
+    else
+    {
+        ec->nonupdate_dwell = 0;
+        ec->latest_correction = -1;
+    }
+    /* Calculate short term power levels using very simple single pole IIRs */
+    /* TODO: Is the nasty modulus approach the fastest, or would a real
+       tx*tx power calculation actually be faster? */
+    ec->tx_power += ((abs(tx) - ec->tx_power) >> 5);
+    ec->rx_power += ((abs(rx) - ec->rx_power) >> 5);
+    ec->clean_rx_power += ((abs(clean_rx) - ec->clean_rx_power) >> 5);
+
+#if defined(XYZZY)
+    if (ec->use_suppressor)
+    {
+    	ec->supp_test1 += (ec->tx_history[ec->curr_pos] - ec->tx_history[(ec->curr_pos - 7) & ec->tap_mask]);
+    	ec->supp_test2 += (ec->tx_history[(ec->curr_pos - 24) & ec->tap_mask] - ec->tx_history[(ec->curr_pos - 31) & ec->tap_mask]);
+    	if (ec->supp_test1 > 42  &&  ec->supp_test2 > 42)
+    	    supp_change = 25;
+    	else
+    	    supp_change = 50;
+    	supp = supp_change + k1*ec->supp1 + k2*ec->supp2;
+	ec->supp2 = ec->supp1;
+	ec->supp1 = supp;
+	clean_rx *= (1 - supp);
+    }
+#endif
+
+    if (ec->use_nlp  &&  ec->rx_power < 32)
+    	clean_rx = 0;
+
+    /* Roll around the rolling buffer */
+    ec->curr_pos = (ec->curr_pos - 1) & ec->tap_mask;
+
+    return clean_rx;
+}
+/*- End of function --------------------------------------------------------*/
+
+static void echo_can_update(struct echo_can_state *ec, short *iref, short *isig)
+{
+	unsigned int x;
+	short result;
+
+	for (x = 0; x < DAHDI_CHUNKSIZE; x++) {
+		result = sample_update(ec, *iref, *isig);
+		*isig++ = result;
+	}
+}
+/*- End of function --------------------------------------------------------*/
+
+static int echo_can_traintap(struct echo_can_state *ec, int pos, short val)
+{
+	/* Reset hang counter to avoid adjustments after
+	   initial forced training */
+	ec->nonupdate_dwell = ec->taps << 1;
+	if (pos >= ec->taps)
+		return 1;
+	ec->fir_taps[pos] = val << 17;
+	ec->fir_taps_short[pos] = val << 1;
+	if (++pos >= ec->taps)
+		return 1;
+	return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+static const struct dahdi_echocan me = {
+	.name = "SEC",
+	.owner = THIS_MODULE,
+	.echo_can_create = echo_can_create,
+	.echo_can_free = echo_can_free,
+	.echo_can_array_update = echo_can_update,
+	.echo_can_traintap = echo_can_traintap,
+};
+
+static int __init mod_init(void)
+{
+	if (dahdi_register_echocan(&me)) {
+		module_printk(KERN_ERR, "could not register with DAHDI core\n");
+
+		return -EPERM;
+	}
+
+	module_printk(KERN_NOTICE, "Registered echo canceler '%s'\n", me.name);
+
+	return 0;
+}
+
+static void __exit mod_exit(void)
+{
+	dahdi_unregister_echocan(&me);
+}
+
+module_param(debug, int, S_IRUGO | S_IWUSR);
+
+MODULE_DESCRIPTION("DAHDI 'SEC' Echo Canceler");
+MODULE_AUTHOR("Steve Underwood <steveu@coppice.org>");
+MODULE_LICENSE("GPL");
+
+module_init(mod_init);
+module_exit(mod_exit);