Initial commit of project.

include/midi.h

@@ -0,0 +1,21 @@
+#ifndef MIDI_H
+#define MIDI_H
+
+#define _POSIX_C_SOURCE 200809L
+#include <alsa/asoundlib.h>
+#include "synth.h"
+
+typedef struct {
+    snd_seq_t *seq;
+    int        port;
+    int        client;
+    Synth     *synth;  // pointer to the synth we'll drive with MIDI events
+} MidiState;
+
+int  midiInit(MidiState *m, Synth *synth);
+void midiListInputs(MidiState *m);
+void midiConnect(MidiState *m, int srcClient, int srcPort);
+void midiClose(MidiState *m);
+void *midiThread(void *arg);
+
+#endif

include/synth.h

@@ -0,0 +1,46 @@
+#ifndef SYNTH_H
+#define SYNTH_H
+
+#include <stdint.h>
+
+#define VOICE_COUNT 8
+
+typedef enum {
+    WAVE_SINE,
+    WAVE_TRIANGLE,
+    WAVE_SAW,
+    WAVE_RAMP,
+    WAVE_PULSE,
+    WAVE_NOISE,
+    WAVE_COUNT  // handy for the modulo wrap on waveform switching
+} Waveform;
+
+typedef struct {
+    float phase;
+    float freqHz;
+    float amp;
+    float targetAmp;
+    int   active;
+    int   midiNote;
+} Voice;
+
+typedef struct {
+    float    sampleRate;
+    float    attackSec;
+    float    releaseSec;
+    float    dutyCycle;
+    Waveform waveform;
+    Voice    voices[VOICE_COUNT];
+    int      lastStolenVoice;
+    float pitchBend;       // -1.0 to +1.0, normalized from raw MIDI value
+    float pitchBendRange;  // semitones, e.g. 2.0f
+} Synth;
+
+void  synthInit(Synth *s, float sampleRate);
+void  synthNoteOn(Synth *s, int midiNote);
+void  synthNoteOff(Synth *s, int midiNote);
+void  synthFillBuffer(Synth *s, int16_t *out, int frames);
+float waveformSample(Waveform w, float phase, float dutyCycle);
+const char *waveformName(Waveform w);
+
+#endif