From 9e75e64787e10556bf2075f241e23e41d8fd2b4c Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Mon, 20 Nov 2017 19:51:24 +0100
Subject: Add DTMF decoder to libdtmf

Note: This decoder has no user yet.
---
 src/test/test_dtmf.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 src/test/test_dtmf.c

(limited to 'src/test/test_dtmf.c')

diff --git a/src/test/test_dtmf.c b/src/test/test_dtmf.c
new file mode 100644
index 0000000..8f56e5c
--- /dev/null
+++ b/src/test/test_dtmf.c
@@ -0,0 +1,114 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <math.h>
+#include <string.h>
+#include "../libdebug/debug.h"
+#include "../libsample/sample.h"
+#include "../libdtmf/dtmf_decode.h"
+#include "../libdtmf/dtmf_encode.h"
+
+#define level2db(level)		(20 * log10(level))
+#define db2level(db)		pow(10, (double)db / 20.0)
+
+#define SAMPLERATE		8000
+
+static double test_frequency[8] = { 697.0, 770.0, 852.0, 941.0, 1209.0, 1336.0, 1477.0, 1633.0 };
+static const char *test_digits = "*#0123456789ABCD";
+
+static sample_t samples[SAMPLERATE];
+
+/* generate samples with two tones */
+static void generate_test_sample(double frequency1, double frequency2, double amplitude1, double amplitude2)
+{
+	int i;
+	double value;
+
+	for (i = 0; i < SAMPLERATE; i++) {
+		value = cos(2.0 * M_PI * frequency1 / (double)SAMPLERATE * i) * amplitude1;
+		value += cos(2.0 * M_PI * frequency2 / (double)SAMPLERATE * i) * amplitude2;
+		samples[i] = value;
+	}
+}
+
+static void check_level(sample_t *samples, const char *desc, double target, int when1, int when2)
+{
+	int i;
+	double amplitude = 0.0, diff;
+
+	for (i = when1; i < when2; i++) {
+		amplitude += samples[i];
+	}
+	amplitude = amplitude / (when2 - when1);
+	diff = fabs(amplitude - target);
+	printf("%s: amplitude between %d and %d ms is %.4f / %.4f db (expected %.4f)\n", desc, when1 * 1000 / SAMPLERATE, when2 * 1000 / SAMPLERATE, amplitude, level2db(amplitude), level2db(target));
+	if (diff < -0.1 || diff > 0.1)
+		printf("**** ERROR: we expected a diff close to 0.0\n");
+	else
+		printf("OK!\n");
+}
+
+static char got_digit;
+
+static void recv_digit(void *inst, char digit, dtmf_meas_t *meas)
+{
+	printf("decoded digit '%c'  frequency %.1f %.1f  amplitude %.1f %.1f dB\n", digit, meas->frequency_low, meas->frequency_high, level2db(meas->amplitude_low), level2db(meas->amplitude_high));
+	got_digit = digit;
+}
+
+int main(void)
+{
+	dtmf_dec_t dtmf_dec;
+	dtmf_enc_t dtmf_enc;
+	sample_t frequency1[SAMPLERATE], frequency2[SAMPLERATE], amplitude1[SAMPLERATE], amplitude2[SAMPLERATE];
+	int f, i;
+	double target;
+
+	dtmf_decode_init(&dtmf_dec, NULL, recv_digit, SAMPLERATE, db2level(0), db2level(-30.0));
+
+	for (f = 0; f < 8; f++) {
+		printf("Testing filter with frequency %.0f Hz:\n", test_frequency[f]);
+		generate_test_sample(test_frequency[f], 0.0, 1.0, 0.0);
+
+		dtmf_decode_filter(&dtmf_dec, samples, SAMPLERATE, frequency1, frequency2, amplitude1, amplitude2);
+
+		if (f == 0 || f == 3)
+			target = sqrt(0.5);
+		else if (f == 1 || f == 2)
+			target = 1.0;
+		else
+			target = 0.0;
+		check_level(amplitude1, "frequency level", target, 900 * SAMPLERATE / 1000, 1000 * SAMPLERATE / 1000);
+		if (f == 4 || f == 7)
+			target = sqrt(0.5);
+		else if (f == 5 || f == 6)
+			target = 1.0;
+		else
+			target = 0.0;
+		check_level(amplitude2, "frequency level", target, 900 * SAMPLERATE / 1000, 1000 * SAMPLERATE / 1000);
+
+		puts("");
+	}
+
+	dtmf_encode_init(&dtmf_enc, SAMPLERATE, 1.0);
+
+	for (i = 0; i < 16; i++) {
+		printf("Testing digit '%c' encoding and decoding:\n", test_digits[i]);
+		memset(samples, 0, sizeof(samples[0]) * SAMPLERATE);
+		dtmf_encode_set_tone(&dtmf_enc, test_digits[i]);
+		dtmf_encode(&dtmf_enc, samples + SAMPLERATE / 10, SAMPLERATE / 20);
+		got_digit = 0;
+		dtmf_decode(&dtmf_dec, samples, SAMPLERATE);
+		if (got_digit == 0)
+			printf("**** ERROR: we expected to decode digit '%c', but nothing was decoded\n", test_digits[i]);
+		else if (got_digit != test_digits[i])
+			printf("**** ERROR: we expected to decode digit '%c', but we decoded digit '%c'\n", test_digits[i], got_digit);
+		else
+			printf("OK!\n");
+		puts("");
+	}
+
+	dtmf_decode_exit(&dtmf_dec);
+
+	return 0;
+}
+
-- 
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