From be3124fe410f37462b6af7131697ee91f33a9ba3 Mon Sep 17 00:00:00 2001
From: markster <markster@5390a7c7-147a-4af0-8ec9-7488f05a26cb>
Date: Wed, 16 Apr 2003 03:31:07 +0000
Subject: Make MEC3 work!

git-svn-id: http://svn.digium.com/svn/zaptel/trunk@171 5390a7c7-147a-4af0-8ec9-7488f05a26cb
---
 mec3.h | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

(limited to 'mec3.h')

diff --git a/mec3.h b/mec3.h
index 28cfa6e..6f42824 100755
--- a/mec3.h
+++ b/mec3.h
@@ -33,6 +33,9 @@
 #define FREE(a) free(a)
 #endif
 
+/*
+ * Define COEFF_BACKUP for experimental coefficient backup code
+ */
 
 
 #define STEP_SIZE			0.4		/* Convergence rate */
@@ -50,7 +53,7 @@
 
 #define HANG_TIME			600		/* Hangover time */
 
-#define NTAPS				128			/* Number of echo can taps */
+#define NTAPS				256			/* Number of echo can taps */
 
 #define BACKUP				256			/* Backup every this number of samples */
 
@@ -62,8 +65,11 @@ typedef struct {
 
 typedef struct {
 	float  	a[NTAPS];				/* Coefficients */
+#ifdef COEFF_BACKUP
 	float  	b[NTAPS];				/* Coefficients */
 	float  	c[NTAPS];				/* Coefficients */
+	int backup;						/* Backup timer */
+#endif	
 	cbuf_f 	ref;					/* Reference excitation */
 	cbuf_f 	sig;					/* Signal (echo + near end + noise) */
 	cbuf_f	e;						/* Error */
@@ -71,7 +77,6 @@ typedef struct {
 	int		taps;					/* Number of taps */
 	int		hcntr;					/* Hangtime counter */
 	int pos;						/* Position in curcular buffers */
-	int backup;						/* Backup timer */
 } echo_can_state_t;
 
 static inline void echo_can_free(echo_can_state_t *ec)
@@ -118,6 +123,7 @@ static inline short echo_can_update(echo_can_state_t *ec, short iref, short isig
 	printf("start: %d, finish: %d\n", ec->start, ec->finish);
 #endif	
 
+#ifdef COEFF_BACKUP
 	if (!ec->backup) {
 		/* Backup coefficients periodically */
 		ec->backup = BACKUP;
@@ -125,6 +131,7 @@ static inline short echo_can_update(echo_can_state_t *ec, short iref, short isig
 		memcpy(ec->b,ec->a,sizeof(ec->b));
 	} else
 		ec->backup--;
+#endif		
 	/* Remove old samples from reference power calculation */
 	ec->refpwr -= (ec->ref.buf[ec->pos] * ec->ref.buf[ec->pos]);
 
@@ -141,6 +148,11 @@ static inline short echo_can_update(echo_can_state_t *ec, short iref, short isig
 	for (x=0;x<ec->taps;x++) 
 		se += ec->a[x] * ec->ref.buf[ec->pos + x];
 
+#if 0
+	if (!(ec->pos2++ % 1024)) {
+		printk("sig: %d, se: %d\n", (int)(32768.0 * sig), (int)(32768.0 * se));
+	}
+#endif
 	u = sig - se;
 	if (ec->hcntr)
 		ec->hcntr--;
@@ -169,14 +181,16 @@ static inline short echo_can_update(echo_can_state_t *ec, short iref, short isig
 				}
 			}
 		} else {
+#ifdef COEFF_BACKUP
 			if (!ec->hcntr) {
 				/* Our double talk detector is turning on for the first time.  Revert
 				   our coefficients, since we're probably well into the double talk by now */
 				memcpy(ec->a, ec->c, sizeof(ec->a));
 			}
+			ec->backup = BACKUP;
+#endif
 			/* Reset hang-time counter, and prevent backups */
 			ec->hcntr = HANG_TIME;
-			ec->backup = BACKUP;
 		}
 	}
 #ifndef NO_ECHO_SUPPRESSOR	
@@ -202,9 +216,11 @@ static inline echo_can_state_t *echo_can_create(int taps, int adaption_mode)
 	taps = NTAPS;
 	ec = MALLOC(sizeof(echo_can_state_t));
 	if (ec) {
-		printk("Allocating MEC3 canceller\n");
-		memset(ec, 0, sizeof(ec));
+		printk("Allocating MEC3 canceller (%d)\n", taps);
+		memset(ec, 0, sizeof(echo_can_state_t));
 		ec->taps = taps;
+		if (ec->taps > NTAPS)
+			ec->taps = NTAPS;
 		ec->pos = ec->taps-1;
 	}
 	return ec;
-- 
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