1 files changed, 107 insertions, 1 deletions
diff --git a/mmband/instrument.c b/mmband/instrument.c
index 96a8952..38c7d43 100644
--- a/mmband/instrument.c
+++ b/mmband/instrument.c
@@ -1,4 +1,110 @@
+#include <math.h>
+#include <stdlib.h>
+
 #include <mmband/api/instrument.h>
 #include <mmband/api/adsr.h>
 
-struct instrument { };
+#include <mmband/waves/waveform.h>
+
+struct oscillation {
+    enum osc_type type; 
+
+    float frequency;
+    float phase;
+    float amplitude;
+};
+
+struct instrument {
+    struct oscillation carrier;
+    struct oscillation modulator;
+
+    float frequency_ratio;
+};
+
+float osc_tick (struct oscillation *osc, int sample_rate) {
+    float sample = 0.0;
+
+    switch (osc->type) {
+        case OSC_NONE:
+            sample = osc->amplitude * none(osc->phase);
+            break;
+        case OSC_SINE:
+            sample = osc->amplitude * sine(osc->phase);
+            break;
+        case OSC_SQUARE:
+            sample = osc->amplitude * square(osc->phase);
+            break;
+        case OSC_SAW:
+            sample = osc->amplitude * saw(osc->phase);
+            break;
+        case OSC_TRIANGLE:
+            sample = osc->amplitude * triangle(osc->phase);
+            break;
+    }
+
+    osc->phase = fmod(osc->phase + osc->frequency * 2.0 * M_PI / sample_rate, 2.0 * M_PI);
+    return sample;
+}
+
+// Currently default to ring modulation
+// TODO: add others
+float modulate (struct oscillation *carrier, struct oscillation *modulator, int sample_rate) {
+    return osc_tick(carrier, sample_rate) * osc_tick(modulator, sample_rate);
+}
+
+instrument_ref ins_new () {
+    instrument_ref instrument = malloc(sizeof(struct instrument));
+
+    instrument->frequency_ratio = 1.0;
+
+    instrument->carrier.type = OSC_SINE;
+    instrument->carrier.amplitude = 0.0;
+    instrument->carrier.frequency = 0.0;
+    instrument->carrier.phase = 0.0;
+
+    instrument->modulator.type = OSC_SINE;
+    instrument->carrier.amplitude = 0.0;
+    instrument->carrier.frequency = 0.0;
+    instrument->carrier.phase = 0.0;
+
+    return instrument;
+}
+
+void ins_free (instrument_ref instrument) {
+    free(instrument);
+}
+
+void ins_set_carrier (instrument_ref instrument, enum osc_type osc) {
+    instrument->carrier.type = osc;
+    instrument->carrier.amplitude = 0.0;
+    instrument->carrier.frequency = 0.0;
+    instrument->carrier.phase = 0.0;
+}
+
+void ins_set_modulator (instrument_ref instrument, enum osc_type osc) {
+    instrument->modulator.type = osc;
+    instrument->modulator.amplitude = 0.0;
+    instrument->modulator.frequency = 0.0;
+    instrument->modulator.phase = 0.0;
+}
+
+void ins_set_carrier_amplitude (instrument_ref instrument, float amplitude) {
+    instrument->carrier.amplitude = amplitude;
+}
+
+void ins_set_modulator_aplitude (instrument_ref instrument, float amplitude) {
+    instrument->modulator.amplitude = amplitude;
+}
+
+void ins_set_frequency_ratio (instrument_ref instrument, float frequency_ratio) {
+    instrument->frequency_ratio = frequency_ratio;
+}
+
+void ins_set_frequency (instrument_ref instrument, float frequency) {
+    instrument->carrier.frequency = frequency;
+    instrument->modulator.frequency = frequency * instrument->frequency_ratio;
+}
+
+float ins_tick (instrument_ref instrument, int sample_rate) {
+    return modulate(&instrument->carrier, &instrument->modulator, sample_rate);
+}