Rename filter -> iir_filter (file name and instance name)

This is useful when using fir_filter in the future.

src/common/Makefile.am

@@ -12,7 +12,7 @@ libcommon_a_SOURCES = \
 	../common/goertzel.c \
 	../common/jitter.c \
 	../common/loss.c \
-	../common/filter.c \
+	../common/iir_filter.c \
 	../common/dtmf.c \
 	../common/samplerate.c \
 	../common/call.c \

src/common/call.c

@@ -497,7 +497,7 @@ int call_init(const char *station_id, const char *audiodev, int samplerate, int
 	if (!audiodev[0])
 		return 0;
 
-	rc = init_samplerate(&call.srstate, 8000.0, (double)samplerate);
+	rc = init_samplerate(&call.srstate, 8000.0, (double)samplerate, 3300.0);
 	if (rc < 0) {
 		PDEBUG(DSENDER, DEBUG_ERROR, "Failed to init sample rate conversion!\n");
 		goto error;

src/common/emphasis.c

@@ -22,7 +22,7 @@
 #include <string.h>
 #include <math.h>
 #include "sample.h"
-#include "filter.h"
+#include "iir_filter.h"
 #include "emphasis.h"
 #include "debug.h"
 
@@ -66,7 +66,7 @@ int init_emphasis(emphasis_t *state, int samplerate, double cut_off)
 	state->d.factor = factor;
 	state->d.amp = 1.0;
 
-	filter_highpass_init(&state->d.hp, CUT_OFF_H, samplerate, 1);
+	iir_highpass_init(&state->d.hp, CUT_OFF_H, samplerate, 1);
 
 	/* calibrate amplification to be neutral at 1000 Hz */
 	gen_sine(test_samples, sizeof(test_samples) / sizeof(test_samples[0]), samplerate, 1000.0);
@@ -128,6 +128,6 @@ void de_emphasis(emphasis_t *state, sample_t *samples, int num)
 /* high pass filter to remove DC and low frequencies */
 void dc_filter(emphasis_t *state, sample_t *samples, int num)
 {
-	filter_process(&state->d.hp, samples, num);
+	iir_process(&state->d.hp, samples, num);
 }
 

src/common/emphasis.h

@@ -5,7 +5,7 @@ typedef struct emphasis {
 		double amp;
 	} p;
 	struct {
-		filter_t hp;
+		iir_filter_t hp;
 		double y_last;
 		double factor;
 		double amp;

src/common/filter.c

@@ -1,99 +0,0 @@
-/* cut-off filter (biquad) based on Nigel Redmon (www.earlevel.com)
- *
- * (C) 2016 by Andreas Eversberg <jolly@eversberg.eu>
- * 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 3 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, see <http://www.gnu.org/licenses/>.
- */
-
-#include <stdio.h>
-#include <stdint.h>
-#include <string.h>
-#include <stdlib.h>
-#include <math.h>
-#include "sample.h"
-#include "filter.h"
-
-#define PI M_PI
-
-void filter_lowpass_init(filter_t *bq, double frequency, int samplerate, int iterations)
-{
-	double Fc, Q, K, norm;
-
-	if (iterations > 64) {
-		fprintf(stderr, "%s failed: too many iterations, please fix!\n", __func__);
-		abort();
-	}
-
-	memset(bq, 0, sizeof(*bq));
-	bq->iter = iterations;
-	Q = pow(sqrt(0.5), 1.0 / (double)iterations); /* 0.7071 @ 1 iteration */
-	Fc = frequency / (double)samplerate;
-	K = tan(PI * Fc);
-	norm = 1 / (1 + K / Q + K * K);
-	bq->a0 = K * K * norm;
-	bq->a1 = 2 * bq->a0;
-	bq->a2 = bq->a0;
-	bq->b1 = 2 * (K * K - 1) * norm;
-	bq->b2 = (1 - K / Q + K * K) * norm;
-}
-
-void filter_highpass_init(filter_t *bq, double frequency, int samplerate, int iterations)
-{
-	double Fc, Q, K, norm;
-
-	memset(bq, 0, sizeof(*bq));
-	bq->iter = iterations;
-	Q = pow(sqrt(0.5), 1.0 / (double)iterations); /* 0.7071 @ 1 iteration */
-	Fc = frequency / (double)samplerate;
-	K = tan(PI * Fc);
-	norm = 1 / (1 + K / Q + K * K);
-	bq->a0 = 1 * norm;
-	bq->a1 = -2 * bq->a0;
-	bq->a2 = bq->a0;
-	bq->b1 = 2 * (K * K - 1) * norm;
-	bq->b2 = (1 - K / Q + K * K) * norm;
-}
-
-void filter_process(filter_t *bq, sample_t *samples, int length)
-{
-	double a0, a1, a2, b1, b2;
-	double *z1, *z2;
-	double in, out;
-	int iterations = bq->iter;
-	int i, j;
-
-	/* get states */
-	a0 = bq->a0;
-	a1 = bq->a1;
-	a2 = bq->a2;
-	b1 = bq->b1;
-	b2 = bq->b2;
-
-	z1 = bq->z1;
-	z2 = bq->z2;
-
-	/* process filter */
-	for (i = 0; i < length; i++) {
-		in = *samples;
-		for (j = 0; j < iterations; j++) {
-			out = in * a0 + z1[j];
-			z1[j] = in * a1 + z2[j] - b1 * out;
-			z2[j] = in * a2 - b2 * out;
-			in = out;
-		}
-		*samples++ = in;
-	}
-}
-

src/common/filter.h

@@ -1,14 +0,0 @@
-#ifndef _FILTER_H
-#define _FILTER_H
-
-typedef struct filter {
-	int iter;
-	double a0, a1, a2, b1, b2;
-	double z1[64], z2[64];
-} filter_t;
-
-void filter_lowpass_init(filter_t *bq, double frequency, int samplerate, int iterations);
-void filter_highpass_init(filter_t *bq, double frequency, int samplerate, int iterations);
-void filter_process(filter_t *bq, sample_t *samples, int length);
-
-#endif /* _FILTER_H */

src/common/fm_modulation.c

@@ -23,7 +23,7 @@
 #include <string.h>
 #include <math.h>
 #include "sample.h"
-#include "filter.h"
+#include "iir_filter.h"
 #include "fm_modulation.h"
 
 //#define FAST_SINE
@@ -110,8 +110,8 @@ void fm_demod_init(fm_demod_t *demod, double samplerate, double offset, double b
 #endif
 
 	/* use fourth order (2 iter) filter, since it is as fast as second order (1 iter) filter */
-	filter_lowpass_init(&demod->lp[0], bandwidth / 2.0, samplerate, 2);
-	filter_lowpass_init(&demod->lp[1], bandwidth / 2.0, samplerate, 2);
+	iir_lowpass_init(&demod->lp[0], bandwidth / 2.0, samplerate, 2);
+	iir_lowpass_init(&demod->lp[1], bandwidth / 2.0, samplerate, 2);
 
 #ifdef FAST_SINE
 	int i;
@@ -169,8 +169,8 @@ void fm_demodulate(fm_demod_t *demod, sample_t *samples, int num, float *buff)
 		Q[s] = i * _sin + q * _cos;
 	}
 	demod->phase = phase;
-	filter_process(&demod->lp[0], I, num);
-	filter_process(&demod->lp[1], Q, num);
+	iir_process(&demod->lp[0], I, num);
+	iir_process(&demod->lp[1], Q, num);
 	last_phase = demod->last_phase;
 	for (s = 0; s < num; s++) {
 		phase = atan2(Q[s], I[s]);

src/common/fm_modulation.h

@@ -15,7 +15,7 @@ typedef struct fm_demod {
 	double phase;		/* current rotation phase (used to shift) */
 	double rot;		/* rotation step per sample to shift rx frequency (used to shift) */
 	double last_phase;	/* last phase of FM (used to demodulate) */
-	filter_t lp[2];		/* filters received IQ signal */
+	iir_filter_t lp[2];	/* filters received IQ signal */
 	double *sin_tab;	/* sine/cosine table rotation */
 } fm_demod_t;
 

src/common/iir_filter.c

@@ -0,0 +1,133 @@
+/* cut-off filter (biquad) based on Nigel Redmon (www.earlevel.com)
+ *
+ * (C) 2016 by Andreas Eversberg <jolly@eversberg.eu>
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include <math.h>
+#include "sample.h"
+#include "iir_filter.h"
+
+#define PI M_PI
+
+void iir_lowpass_init(iir_filter_t *filter, double frequency, int samplerate, int iterations)
+{
+	double Fc, Q, K, norm;
+
+	if (iterations > 64) {
+		fprintf(stderr, "%s failed: too many iterations, please fix!\n", __func__);
+		abort();
+	}
+
+	memset(filter, 0, sizeof(*filter));
+	filter->iter = iterations;
+	Q = pow(sqrt(0.5), 1.0 / (double)iterations); /* 0.7071 @ 1 iteration */
+	Fc = frequency / (double)samplerate;
+	K = tan(PI * Fc);
+	norm = 1 / (1 + K / Q + K * K);
+	filter->a0 = K * K * norm;
+	filter->a1 = 2 * filter->a0;
+	filter->a2 = filter->a0;
+	filter->b1 = 2 * (K * K - 1) * norm;
+	filter->b2 = (1 - K / Q + K * K) * norm;
+}
+
+void iir_highpass_init(iir_filter_t *filter, double frequency, int samplerate, int iterations)
+{
+	double Fc, Q, K, norm;
+
+	memset(filter, 0, sizeof(*filter));
+	filter->iter = iterations;
+	Q = pow(sqrt(0.5), 1.0 / (double)iterations); /* 0.7071 @ 1 iteration */
+	Fc = frequency / (double)samplerate;
+	K = tan(PI * Fc);
+	norm = 1 / (1 + K / Q + K * K);
+	filter->a0 = 1 * norm;
+	filter->a1 = -2 * filter->a0;
+	filter->a2 = filter->a0;
+	filter->b1 = 2 * (K * K - 1) * norm;
+	filter->b2 = (1 - K / Q + K * K) * norm;
+}
+
+void iir_bandpass_init(iir_filter_t *filter, double frequency, int samplerate, int iterations)
+{
+	double Fc, Q, K, norm;
+
+	memset(filter, 0, sizeof(*filter));
+	filter->iter = iterations;
+	Q = pow(sqrt(0.5), 1.0 / (double)iterations); /* 0.7071 @ 1 iteration */
+	Fc = frequency / (double)samplerate;
+	K = tan(PI * Fc);
+	norm = 1 / (1 + K / Q + K * K);
+	filter->a0 = K / Q * norm;
+	filter->a1 = 0;
+	filter->a2 = -filter->a0;
+	filter->b1 = 2 * (K * K - 1) * norm;
+	filter->b2 = (1 - K / Q + K * K) * norm;
+}
+
+void iir_notch_init(iir_filter_t *filter, double frequency, int samplerate, int iterations)
+{
+	double Fc, Q, K, norm;
+
+	memset(filter, 0, sizeof(*filter));
+	filter->iter = iterations;
+	Q = pow(sqrt(0.5), 1.0 / (double)iterations); /* 0.7071 @ 1 iteration */
+	Fc = frequency / (double)samplerate;
+	K = tan(PI * Fc);
+	norm = 1 / (1 + K / Q + K * K);
+	filter->a0 = (1 + K * K) * norm;
+	filter->a1 = 2 * (K * K - 1) * norm;
+	filter->a2 = filter->a0;
+	filter->b1 = filter->a1;
+	filter->b2 = (1 - K / Q + K * K) * norm;
+}
+            
+void iir_process(iir_filter_t *filter, sample_t *samples, int length)
+{
+	double a0, a1, a2, b1, b2;
+	double *z1, *z2;
+	double in, out;
+	int iterations = filter->iter;
+	int i, j;
+
+	/* get states */
+	a0 = filter->a0;
+	a1 = filter->a1;
+	a2 = filter->a2;
+	b1 = filter->b1;
+	b2 = filter->b2;
+
+	z1 = filter->z1;
+	z2 = filter->z2;
+
+	/* process filter */
+	for (i = 0; i < length; i++) {
+		in = *samples;
+		for (j = 0; j < iterations; j++) {
+			out = in * a0 + z1[j];
+			z1[j] = in * a1 + z2[j] - b1 * out;
+			z2[j] = in * a2 - b2 * out;
+			in = out;
+		}
+		*samples++ = in;
+	}
+}
+

src/common/iir_filter.h

@@ -0,0 +1,16 @@
+#ifndef _FILTER_H
+#define _FILTER_H
+
+typedef struct iir_filter {
+	int iter;
+	double a0, a1, a2, b1, b2;
+	double z1[64], z2[64];
+} iir_filter_t;
+
+void iir_lowpass_init(iir_filter_t *filter, double frequency, int samplerate, int iterations);
+void iir_highpass_init(iir_filter_t *filter, double frequency, int samplerate, int iterations);
+void iir_bandpass_init(iir_filter_t *filter, double frequency, int samplerate, int iterations);
+void iir_notch_init(iir_filter_t *filter, double frequency, int samplerate, int iterations);
+void iir_process(iir_filter_t *filter, sample_t *samples, int length);
+
+#endif /* _FILTER_H */

src/common/samplerate.c

@@ -25,7 +25,7 @@
 #include "sample.h"
 #include "samplerate.h"
 
-int init_samplerate(samplerate_t *state, double low_samplerate, double high_samplerate)
+int init_samplerate(samplerate_t *state, double low_samplerate, double high_samplerate, double filter_cutoff)
 {
 	memset(state, 0, sizeof(*state));
 	state->factor = high_samplerate / low_samplerate;
@@ -34,8 +34,8 @@ int init_samplerate(samplerate_t *state, double low_samplerate, double high_samp
 		abort();
 	}
 
-	filter_lowpass_init(&state->up.lp, 3300.0, high_samplerate, 2);
-	filter_lowpass_init(&state->down.lp, 3300.0, high_samplerate, 2);
+	iir_lowpass_init(&state->up.lp, filter_cutoff, high_samplerate, 2);
+	iir_lowpass_init(&state->down.lp, filter_cutoff, high_samplerate, 2);
 
 	return 0;
 }
@@ -49,7 +49,7 @@ int samplerate_downsample(samplerate_t *state, sample_t *samples, int input_num)
 	sample_t last_sample;
 
 	/* filter down */
-	filter_process(&state->down.lp, samples, input_num);
+	iir_process(&state->down.lp, samples, input_num);
 
 	/* get last sample for interpolation */
 	last_sample = state->down.last_sample;
@@ -144,7 +144,7 @@ int samplerate_upsample(samplerate_t *state, sample_t *input, int input_num, sam
 	state->up.in_index = in_index;
 
 	/* filter up */
-	filter_process(&state->up.lp, samples, output_num);
+	iir_process(&state->up.lp, samples, output_num);
 
 	if (input == output) {
 		/* copy samples */

src/common/samplerate.h

@@ -1,19 +1,19 @@
-#include "filter.h"
+#include "iir_filter.h"
 
 typedef struct samplerate {
 	double factor;
 	struct {
-		filter_t lp;
+		iir_filter_t lp;
 		sample_t last_sample;
 		double in_index;
 	} down;
 	struct {
-		filter_t lp;
+		iir_filter_t lp;
 		sample_t last_sample;
 		double in_index;
 	} up;
 } samplerate_t;
 
-int init_samplerate(samplerate_t *state, double low_samplerate, double high_samplerate);
+int init_samplerate(samplerate_t *state, double low_samplerate, double high_samplerate, double filter_cutoff);
 int samplerate_downsample(samplerate_t *state, sample_t *samples, int input_num);
 int samplerate_upsample(samplerate_t *state, sample_t *input, int input_num, sample_t *output);

src/common/sdr.c

@@ -24,7 +24,7 @@
 #include <errno.h>
 #include <math.h>
 #include "sample.h"
-#include "filter.h"
+#include "iir_filter.h"
 #include "fm_modulation.h"
 #include "sender.h"
 #ifdef HAVE_UHD

src/common/sender.c

@@ -114,7 +114,7 @@ int sender_create(sender_t *sender, int kanal, double sendefrequenz, double empf
 		}
 	}
 
-	rc = init_samplerate(&sender->srstate, 8000.0, (double)samplerate);
+	rc = init_samplerate(&sender->srstate, 8000.0, (double)samplerate, 3300.0);
 	if (rc < 0) {
 		PDEBUG(DSENDER, DEBUG_ERROR, "Failed to init sample rate conversion!\n");
 		goto error;