From a1a0b03ab9cb691dfb3d1605adbf18549d651cd6 Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Tue, 5 Oct 2021 10:10:02 -0400
Subject: [PATCH] TT#136956 refactor DTMF frequency generator code

Change-Id: Ibcecc6dd04971e575747e3609f01858435351d92
---
 lib/codeclib.c | 40 +++++++++++++++++++++++--------------
 lib/dtmflib.c  | 54 +++++++++++++++++++++++++++++++++++---------------
 lib/dtmflib.h  |  4 ++--
 3 files changed, 65 insertions(+), 33 deletions(-)

diff --git a/lib/codeclib.c b/lib/codeclib.c
index 56af4f61c..c3757550b 100644
--- a/lib/codeclib.c
+++ b/lib/codeclib.c
@@ -2538,6 +2538,29 @@ static const char *dtmf_decoder_init(decoder_t *dec, const str *fmtp, const str
 	return NULL;
 }
 
+static AVFrame *dtmf_frame_int16_t_mono(unsigned long frame_ts, unsigned long num_samples, unsigned int event,
+		unsigned int volume,
+		unsigned int sample_rate)
+{
+	// synthesise PCM
+	// first get our frame and figure out how many samples we need, and the start offset
+	AVFrame *frame = av_frame_alloc();
+	frame->nb_samples = num_samples;
+	frame->format = AV_SAMPLE_FMT_S16;
+	frame->sample_rate = sample_rate;
+	frame->channel_layout = AV_CH_LAYOUT_MONO;
+	frame->pts = frame_ts;
+	if (av_frame_get_buffer(frame, 0) < 0)
+		abort();
+
+	// fill samples
+	dtmf_samples_int16_t_mono(frame->extended_data[0], frame_ts, frame->nb_samples, event,
+			volume, sample_rate);
+
+	return frame;
+
+}
+
 static int dtmf_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 	struct telephone_event_payload *dtmf;
 	if (data->len < sizeof(*dtmf)) {
@@ -2572,21 +2595,8 @@ static int dtmf_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 		return -1;
 	}
 
-	// synthesise PCM
-	// first get our frame and figure out how many samples we need, and the start offset
-	AVFrame *frame = av_frame_alloc();
-	frame->nb_samples = num_samples;
-	frame->format = AV_SAMPLE_FMT_S16;
-	frame->sample_rate = dec->in_format.clockrate;
-	frame->channel_layout = AV_CH_LAYOUT_MONO;
-	frame->pts = frame_ts;
-	if (av_frame_get_buffer(frame, 0) < 0)
-		abort();
-
-	// fill samples
-	dtmf_samples(frame->extended_data[0], frame_ts, frame->nb_samples, dtmf->event,
-			dtmf->volume, dec->in_format.clockrate);
-
+	AVFrame *frame = dtmf_frame_int16_t_mono(frame_ts, num_samples, dtmf->event, dtmf->volume,
+			dec->in_format.clockrate);
 	g_queue_push_tail(out, frame);
 
 	dec->u.dtmf.duration = duration;
diff --git a/lib/dtmflib.c b/lib/dtmflib.c
index 466d8efbe..a2c6da269 100644
--- a/lib/dtmflib.c
+++ b/lib/dtmflib.c
@@ -35,8 +35,43 @@ INLINE double freq2iter(unsigned int hz, unsigned int sample_rate) {
 	return ret;
 }
 
-void dtmf_samples(void *buf, unsigned long offset, unsigned long num, unsigned int event, unsigned int volume,
-		unsigned int sample_rate)
+// only packed audio supported
+
+#define freq_samples_x(type, mult) \
+INLINE void freq_samples_ ## type(type *samples, unsigned long offset, unsigned long num, unsigned int prim_freq, \
+		unsigned int sec_freq, unsigned int volume, unsigned int sample_rate, unsigned int channels) \
+{ \
+	if (!channels) \
+		channels = 1; \
+	/* XXX initialise/save these when the DTMF event starts */ \
+	double vol = pow(1.122018, volume) * 2.0; \
+ \
+	double prim_iter = freq2iter(prim_freq, sample_rate); \
+	double sec_iter = sec_freq ? freq2iter(sec_freq, sample_rate) : 0; \
+ \
+	num += offset; /* end here */ \
+	while (offset < num) { \
+		double prim = sin(prim_iter * offset) / vol; \
+		type sample; \
+		if (!sec_freq) \
+			sample = prim * mult; \
+		else { \
+			double sec = sin(sec_iter * offset) / vol; \
+			sample = prim * mult + sec * mult; \
+		} \
+		for (unsigned int ch = 0; ch < channels; ch++) \
+			*samples++ = sample; \
+		offset++; \
+	} \
+}
+
+freq_samples_x(int16_t, 32767.0)
+freq_samples_x(int32_t, 2147483647.0)
+freq_samples_x(double, 1.0)
+freq_samples_x(float, 1.0)
+
+void dtmf_samples_int16_t_mono(void *buf, unsigned long offset, unsigned long num, unsigned int event,
+		unsigned int volume, unsigned int sample_rate)
 {
 	int16_t *samples = buf;
 	const struct dtmf_freq *df;
@@ -54,18 +89,5 @@ void dtmf_samples(void *buf, unsigned long offset, unsigned long num, unsigned i
 	}
 	df = &dtmf_freqs[event];
 
-	// XXX initialise/save these when the DTMF event starts
-	double vol = pow(1.122018, volume) * 2.0;
-
-	double prim_freq = freq2iter(df->prim, sample_rate);
-	double sec_freq = freq2iter(df->sec, sample_rate);
-
-	num += offset; // end here
-	while (offset < num) {
-		double prim = sin(prim_freq * offset) / vol;
-		double sec = sin(sec_freq * offset) / vol;
-		int16_t sample = prim * 32767.0 + sec * 32767.0;
-		*samples++ = sample;
-		offset++;
-	}
+	freq_samples_int16_t(samples, offset, num, df->prim, df->sec, volume, sample_rate, 1);
 }
diff --git a/lib/dtmflib.h b/lib/dtmflib.h
index 4d1b08e03..8c85d9e6c 100644
--- a/lib/dtmflib.h
+++ b/lib/dtmflib.h
@@ -22,8 +22,8 @@ struct telephone_event_payload {
 } __attribute__ ((packed));
 
 
-void dtmf_samples(void *buf, unsigned long offset, unsigned long num, unsigned int event, unsigned int volume,
-		unsigned int sample_rate);
+void dtmf_samples_int16_t_mono(void *buf, unsigned long offset, unsigned long num, unsigned int event,
+		unsigned int volume, unsigned int sample_rate);
 
 
 #endif