synthio: more fir-filter removal; fix biquad logic errors

Author: jepler

shared-bindings/synthio/Synthesizer.c

@@ -53,7 +53,6 @@
 //|         channel_count: int = 1,
 //|         waveform: Optional[ReadableBuffer] = None,
 //|         envelope: Optional[Envelope] = None,
-//|         filter: Optional[ReadableBuffer] = None,
 //|     ) -> None:
 //|         """Create a synthesizer object.
 //|
@@ -66,17 +65,15 @@
 //|         :param int sample_rate: The desired playback sample rate; higher sample rate requires more memory
 //|         :param int channel_count: The number of output channels (1=mono, 2=stereo)
 //|         :param ReadableBuffer waveform: A single-cycle waveform. Default is a 50% duty cycle square wave. If specified, must be a ReadableBuffer of type 'h' (signed 16 bit)
-//|         :param ReadableBuffer filter: Coefficients of an FIR filter to apply to notes with ``filter=True``. If specified, must be a ReadableBuffer of type 'h' (signed 16 bit)
 //|         :param Optional[Envelope] envelope: An object that defines the loudness of a note over time. The default envelope, `None` provides no ramping, voices turn instantly on and off.
 //|         """
 STATIC mp_obj_t synthio_synthesizer_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    enum { ARG_sample_rate, ARG_channel_count, ARG_waveform, ARG_envelope, ARG_filter };
+    enum { ARG_sample_rate, ARG_channel_count, ARG_waveform, ARG_envelope };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_sample_rate, MP_ARG_INT | MP_ARG_KW_ONLY, {.u_int = 11025} },
         { MP_QSTR_channel_count, MP_ARG_INT | MP_ARG_KW_ONLY, {.u_int = 1} },
         { MP_QSTR_waveform, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none } },
         { MP_QSTR_envelope, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none } },
-        { MP_QSTR_filter, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none } },
     };
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
@@ -88,7 +85,6 @@ STATIC mp_obj_t synthio_synthesizer_make_new(const mp_obj_type_t *type, size_t n
         args[ARG_sample_rate].u_int,
         args[ARG_channel_count].u_int,
         args[ARG_waveform].u_obj,
-        args[ARG_filter].u_obj,
         args[ARG_envelope].u_obj);
 
     return MP_OBJ_FROM_PTR(self);

shared-bindings/synthio/Synthesizer.h

@@ -32,7 +32,7 @@
 extern const mp_obj_type_t synthio_synthesizer_type;
 
 void common_hal_synthio_synthesizer_construct(synthio_synthesizer_obj_t *self,
-    uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj, mp_obj_t filter_obj,
+    uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj,
     mp_obj_t envelope_obj);
 void common_hal_synthio_synthesizer_deinit(synthio_synthesizer_obj_t *self);
 bool common_hal_synthio_synthesizer_deinited(synthio_synthesizer_obj_t *self);

shared-module/synthio/Biquad.c

@@ -94,7 +94,7 @@ mp_obj_t common_hal_synthio_new_bpf(mp_float_t w0, mp_float_t Q) {
     return namedtuple_make_new((const mp_obj_type_t *)&synthio_biquad_type_obj, MP_ARRAY_SIZE(out_args), 0, out_args);
 }
 
-#define BIQUAD_SHIFT (16)
+#define BIQUAD_SHIFT (19)
 STATIC int32_t biquad_scale_arg_obj(mp_obj_t arg) {
     return (int32_t)MICROPY_FLOAT_C_FUN(round)(MICROPY_FLOAT_C_FUN(ldexp)(mp_obj_get_float(arg), BIQUAD_SHIFT));
 }
@@ -110,6 +110,10 @@ void synthio_biquad_filter_assign(biquad_filter_state *st, mp_obj_t biquad_obj)
     }
 }
 
+void synthio_biquad_filter_reset(biquad_filter_state *st) {
+    memset(&st->x, 0, 8 * sizeof(int16_t));
+}
+
 void synthio_biquad_filter_samples(biquad_filter_state *st, int32_t *out0, const int32_t *in0, size_t n0, size_t n_channels) {
     int32_t a1 = st->a1;
     int32_t a2 = st->a2;
@@ -134,7 +138,7 @@ void synthio_biquad_filter_samples(biquad_filter_state *st, int32_t *out0, const
             x0 = input;
             y1 = y0;
             y0 = output;
-            *out = output;
+            *out += output;
         }
         st->x[i][0] = x0;
         st->x[i][1] = x1;

shared-module/synthio/Biquad.h

@@ -34,4 +34,5 @@ typedef struct {
 } biquad_filter_state;
 
 void synthio_biquad_filter_assign(biquad_filter_state *st, mp_obj_t biquad_obj);
+void synthio_biquad_filter_reset(biquad_filter_state *st);
 void synthio_biquad_filter_samples(biquad_filter_state *st, int32_t *out, const int32_t *in, size_t n_samples, size_t n_channels);

shared-module/synthio/MidiTrack.c

@@ -122,7 +122,7 @@ void common_hal_synthio_miditrack_construct(synthio_miditrack_obj_t *self,
     self->track.buf = (void *)buffer;
     self->track.len = len;
 
-    synthio_synth_init(&self->synth, sample_rate, 1, waveform_obj, mp_const_none, envelope_obj);
+    synthio_synth_init(&self->synth, sample_rate, 1, waveform_obj, envelope_obj);
 
     start_parse(self);
 }

shared-module/synthio/Note.c

@@ -148,6 +148,7 @@ void synthio_note_recalculate(synthio_note_obj_t *self, int32_t sample_rate) {
 
 void synthio_note_start(synthio_note_obj_t *self, int32_t sample_rate) {
     synthio_note_recalculate(self, sample_rate);
+    synthio_biquad_filter_reset(&self->filter_state);
 }
 
 // Perform a pitch bend operation

shared-module/synthio/Synthesizer.c

@@ -33,10 +33,10 @@
 
 
 void common_hal_synthio_synthesizer_construct(synthio_synthesizer_obj_t *self,
-    uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj, mp_obj_t filter_obj,
+    uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj,
     mp_obj_t envelope_obj) {
 
-    synthio_synth_init(&self->synth, sample_rate, channel_count, waveform_obj, filter_obj, envelope_obj);
+    synthio_synth_init(&self->synth, sample_rate, channel_count, waveform_obj, envelope_obj);
     self->blocks = mp_obj_new_list(0, NULL);
 }
 

shared-module/synthio/__init__.c

@@ -389,7 +389,6 @@ bool synthio_synth_deinited(synthio_synth_t *synth) {
 }
 
 void synthio_synth_deinit(synthio_synth_t *synth) {
-    synth->filter_buffer = NULL;
     synth->buffers[0] = NULL;
     synth->buffers[1] = NULL;
 }
@@ -403,17 +402,12 @@ mp_obj_t synthio_synth_envelope_get(synthio_synth_t *synth) {
     return synth->envelope_obj;
 }
 
-void synthio_synth_init(synthio_synth_t *synth, uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj, mp_obj_t filter_obj, mp_obj_t envelope_obj) {
+void synthio_synth_init(synthio_synth_t *synth, uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj, mp_obj_t envelope_obj) {
     synthio_synth_parse_waveform(&synth->waveform_bufinfo, waveform_obj);
-    synthio_synth_parse_filter(&synth->filter_bufinfo, filter_obj);
     mp_arg_validate_int_range(channel_count, 1, 2, MP_QSTR_channel_count);
     synth->buffer_length = SYNTHIO_MAX_DUR * SYNTHIO_BYTES_PER_SAMPLE * channel_count;
     synth->buffers[0] = m_malloc(synth->buffer_length, false);
     synth->buffers[1] = m_malloc(synth->buffer_length, false);
-    if (synth->filter_bufinfo.len) {
-        synth->filter_buffer_length = (synth->filter_bufinfo.len + SYNTHIO_MAX_DUR) * channel_count * sizeof(int32_t);
-        synth->filter_buffer = m_malloc(synth->filter_buffer_length, false);
-    }
     synth->channel_count = channel_count;
     synth->other_channel = -1;
     synth->waveform_obj = waveform_obj;
@@ -453,11 +447,6 @@ void synthio_synth_parse_waveform(mp_buffer_info_t *bufinfo_waveform, mp_obj_t w
     parse_common(bufinfo_waveform, waveform_obj, MP_QSTR_waveform, 16384);
 }
 
-void synthio_synth_parse_filter(mp_buffer_info_t *bufinfo_filter, mp_obj_t filter_obj) {
-    *bufinfo_filter = ((mp_buffer_info_t) { .buf = NULL, .len = 0 });
-    parse_common(bufinfo_filter, filter_obj, MP_QSTR_filter, 128);
-}
-
 STATIC int find_channel_with_note(synthio_synth_t *synth, mp_obj_t note) {
     for (int i = 0; i < CIRCUITPY_SYNTHIO_MAX_CHANNELS; i++) {
         if (synth->span.note_obj[i] == note) {

shared-module/synthio/__init__.h

@@ -64,12 +64,11 @@ typedef struct synthio_synth {
     uint32_t sample_rate;
     uint32_t total_envelope;
     int16_t *buffers[2];
-    int32_t *filter_buffer;
     uint8_t channel_count;
-    uint16_t buffer_length, filter_buffer_length;
+    uint16_t buffer_length;
     uint16_t last_buffer_length;
     uint8_t other_channel, buffer_index, other_buffer_index;
-    mp_buffer_info_t waveform_bufinfo, filter_bufinfo;
+    mp_buffer_info_t waveform_bufinfo;
     synthio_envelope_definition_t global_envelope_definition;
     mp_obj_t waveform_obj, filter_obj, envelope_obj;
     synthio_midi_span_t span;
@@ -91,7 +90,7 @@ typedef struct {
 void synthio_synth_synthesize(synthio_synth_t *synth, uint8_t **buffer, uint32_t *buffer_length, uint8_t channel);
 void synthio_synth_deinit(synthio_synth_t *synth);
 bool synthio_synth_deinited(synthio_synth_t *synth);
-void synthio_synth_init(synthio_synth_t *synth, uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj, mp_obj_t filter_obj, mp_obj_t envelope);
+void synthio_synth_init(synthio_synth_t *synth, uint32_t sample_rate, int channel_count, mp_obj_t waveform_obj, mp_obj_t envelope);
 void synthio_synth_get_buffer_structure(synthio_synth_t *synth, bool single_channel_output,
     bool *single_buffer, bool *samples_signed, uint32_t *max_buffer_length, uint8_t *spacing);
 void synthio_synth_reset_buffer(synthio_synth_t *synth, bool single_channel_output, uint8_t channel);