From cf2cfcd8a96921dbe812647045dff71ab63989cd Mon Sep 17 00:00:00 2001
From: Mitja Felicijan <mitja.felicijan@gmail.com>
Date: Wed, 9 Oct 2024 03:12:15 +0200
Subject: Added synth thread that plays a simple note

---
 Makefile |  4 ++--
 main.c   | 13 ++++++++++++-
 synth.c  | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 synth.h  | 11 +++++++++++
 4 files changed, 92 insertions(+), 3 deletions(-)
 create mode 100644 synth.c
 create mode 100644 synth.h

diff --git a/Makefile b/Makefile
index 98a41d3..8681948 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC      := cc
-CFLAGS  := -Wall -Wextra -Wshadow -Wunused -Wswitch-enum -Wpedantic -Wundef
+CFLAGS  := -Wall -Wextra -Wshadow -Wunused -Wswitch-enum -Wpedantic -ggdb
 LDFLAGS := -lm -ldl -lpthread -lasound
-FILES   := main.c midi.c minisdl_audio.c
+FILES   := main.c midi.c synth.c minisdl_audio.c
 PROG    := ttdaw
 
 $(PROG): main.c
diff --git a/main.c b/main.c
index 3a45592..5a1916e 100644
--- a/main.c
+++ b/main.c
@@ -6,6 +6,7 @@
 
 #include "version.h"
 #include "midi.h"
+#include "synth.h"
 
 void help(const char *argv0) {
 	printf("Usage: %s [options]\n"
@@ -69,7 +70,16 @@ int main(int argc, char *argv[]) {
 	fprintf(stdout, "> Device port:   %s\n", port_name);
 	fprintf(stdout, "> Soundfont:     %s\n", soundfont_file);
 
-	// Create and start MIDI thread.
+	// Create synth thread.
+	pthread_t synth_thread;
+	SynthArgs synth_args = { soundfont_file };
+
+	if (pthread_create(&synth_thread, NULL, synth, (void*)&synth_args) != 0) {
+		fprintf(stderr, "Error creating synth thread\n");
+		return 1;
+	}
+
+	// Create MIDI thread.
 	pthread_t midi_thread;
 	MidiArgs midi_args = { port_name };
 
@@ -79,6 +89,7 @@ int main(int argc, char *argv[]) {
 	}
 
 	pthread_join(midi_thread, NULL);
+	pthread_join(synth_thread, NULL);
 
 	fprintf(stdout, "Exiting...\n");
 	return 0;
diff --git a/synth.c b/synth.c
new file mode 100644
index 0000000..d391056
--- /dev/null
+++ b/synth.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <unistd.h>
+
+#include "synth.h"
+#include "minisdl_audio.h"
+
+#define TSF_IMPLEMENTATION
+#include "tsf.h"
+
+static tsf* g_TinySoundFont;
+static SDL_mutex* g_Mutex;
+
+// Render the audio samples in float format.
+static void AudioCallback(void* data, Uint8 *stream, int len) {
+	int SampleCount = (len / (2 * sizeof(float))); // 2 output channels.
+	SDL_LockMutex(g_Mutex); // Get exclusive lock.
+	tsf_render_float(g_TinySoundFont, (float*)stream, SampleCount, 0);
+	SDL_UnlockMutex(g_Mutex);
+}
+
+void *synth(void *arg) {
+	SynthArgs* args = (SynthArgs*)arg;
+
+	SDL_AudioSpec OutputAudioSpec;
+	OutputAudioSpec.freq = 44100;
+	OutputAudioSpec.format = AUDIO_F32;
+	OutputAudioSpec.channels = 2;
+	OutputAudioSpec.samples = 4096;
+	OutputAudioSpec.callback = AudioCallback;
+
+	// Initialize the audio system.
+	if (SDL_AudioInit(TSF_NULL) < 0) {
+		fprintf(stderr, "Could not initialize audio hardware or driver\n");
+		exit(1);
+	}
+
+	// Load the SoundFont from a file.
+	g_TinySoundFont = tsf_load_filename(args->soundfont_file);
+	if (!g_TinySoundFont) {
+		fprintf(stderr, "Could not load SoundFont\n");
+		exit(1);
+	}
+
+	// Set the SoundFont rendering output mode.
+	tsf_set_output(g_TinySoundFont, TSF_STEREO_INTERLEAVED, OutputAudioSpec.freq, 0);
+
+	// Create the mutex.
+	g_Mutex = SDL_CreateMutex();
+
+	// Request the desired audio output format.
+	if (SDL_OpenAudio(&OutputAudioSpec, TSF_NULL) < 0) {
+		fprintf(stderr, "Could not open the audio hardware or the desired audio output format\n");
+		exit(1);
+	}
+
+	SDL_PauseAudio(0);
+
+	while (1) {
+		sleep(1);
+
+		SDL_LockMutex(g_Mutex);
+		tsf_note_off(g_TinySoundFont, 1, 50);
+		tsf_note_on(g_TinySoundFont, 1, 50, 1.0f);
+		SDL_UnlockMutex(g_Mutex);
+	}
+}
+
diff --git a/synth.h b/synth.h
new file mode 100644
index 0000000..1976745
--- /dev/null
+++ b/synth.h
@@ -0,0 +1,11 @@
+#ifndef SYNTH_H_
+#define SYNTH_H_
+
+typedef struct {
+	char *soundfont_file;
+} SynthArgs;
+
+void *synth(void *arg);
+
+#endif //  SYNTH_H_
+
-- 
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