synthio: Finish ading SWEEP_IN

Author: jepler

shared-bindings/synthio/__init__.h

@@ -30,7 +30,7 @@
 #include "py/enum.h"
 
 typedef enum synthio_bend_mode_e {
-    SYNTHIO_BEND_MODE_STATIC, SYNTHIO_BEND_MODE_VIBRATO, SYNTHIO_BEND_MODE_SWEEP
+    SYNTHIO_BEND_MODE_STATIC, SYNTHIO_BEND_MODE_VIBRATO, SYNTHIO_BEND_MODE_SWEEP, SYNTHIO_BEND_MODE_SWEEP_IN
 } synthio_bend_mode_t;
 
 extern const cp_enum_obj_t bend_mode_VIBRATO_obj;

shared-module/synthio/Note.c

@@ -224,6 +224,8 @@ STATIC int synthio_bend_value(synthio_note_obj_t *self, int16_t dur) {
             return synthio_lfo_step(&self->bend_state, dur);
         case SYNTHIO_BEND_MODE_SWEEP:
             return synthio_sweep_step(&self->bend_state, dur);
+        case SYNTHIO_BEND_MODE_SWEEP_IN:
+            return synthio_sweep_in_step(&self->bend_state, dur);
         default:
             return 32768;
     }

shared-module/synthio/__init__.c

@@ -480,25 +480,35 @@ void synthio_lfo_set(synthio_lfo_state_t *state, const synthio_lfo_descr_t *desc
     state->dds = synthio_frequency_convert_float_to_dds(descr->frequency * 65536, sample_rate);
 }
 
-int synthio_sweep_step(synthio_lfo_state_t *state, uint16_t dur) {
+STATIC int synthio_lfo_step_common(synthio_lfo_state_t *state, uint16_t dur) {
     uint32_t phase = state->phase;
     uint16_t whole_phase = phase >> 16;
 
     // advance the phase accumulator
     state->phase = phase + state->dds * dur;
-    if (state->phase < phase) {
+
+    return whole_phase;
+}
+STATIC int synthio_lfo_sweep_common(synthio_lfo_state_t *state, uint16_t dur) {
+    uint16_t whole_phase = synthio_lfo_step_common(state, dur);
+    if (state->phase < state->dds) {
         state->phase = 0xffffffff;
     }
-    return (state->amplitude_scaled * whole_phase) / 65536 + state->offset_scaled;
+    return whole_phase;
 }
 
-int synthio_lfo_step(synthio_lfo_state_t *state, uint16_t dur) {
-    uint32_t phase = state->phase;
-    uint16_t whole_phase = phase >> 16;
+int synthio_sweep_step(synthio_lfo_state_t *state, uint16_t dur) {
+    uint16_t whole_phase = synthio_lfo_sweep_common(state, dur);
+    return (state->amplitude_scaled * whole_phase) / 65536 + state->offset_scaled;
+}
 
-    // advance the phase accumulator
-    state->phase = phase + state->dds * dur;
+int synthio_sweep_in_step(synthio_lfo_state_t *state, uint16_t dur) {
+    uint16_t whole_phase = 65535 - synthio_lfo_sweep_common(state, dur);
+    return (state->amplitude_scaled * whole_phase) / 65536 + state->offset_scaled;
+}
 
+int synthio_lfo_step(synthio_lfo_state_t *state, uint16_t dur) {
+    uint16_t whole_phase = synthio_lfo_step_common(state, dur);
     // create a triangle wave, it's quick and easy
     int v;
     if (whole_phase < 16384) { // ramp from 0 to amplitude

shared-module/synthio/__init__.h

@@ -111,3 +111,4 @@ uint32_t synthio_frequency_convert_scaled_to_dds(uint64_t frequency_scaled, int3
 void synthio_lfo_set(synthio_lfo_state_t *state, const synthio_lfo_descr_t *descr, uint32_t sample_rate);
 int synthio_lfo_step(synthio_lfo_state_t *state, uint16_t dur);
 int synthio_sweep_step(synthio_lfo_state_t *state, uint16_t dur);
+int synthio_sweep_in_step(synthio_lfo_state_t *state, uint16_t dur);