247 lines
8.4 KiB
C
247 lines
8.4 KiB
C
/*
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* This file is part of the Micro Python project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2021 Artyom Skrobov
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "py/runtime.h"
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#include "shared-bindings/synthio/MidiTrack.h"
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#define BITS_PER_SAMPLE (16)
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#define BYTES_PER_SAMPLE (BITS_PER_SAMPLE / 8)
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#define MAX_DUR (512)
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#define SILENCE (0x80)
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STATIC NORETURN void raise_midi_stream_error(uint32_t pos) {
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mp_raise_ValueError_varg(translate("Error in MIDI stream at position %d"), pos);
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}
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STATIC uint8_t parse_note(const uint8_t *buffer, uint32_t len, uint32_t *pos) {
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if (*pos + 1 >= len) {
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raise_midi_stream_error(*pos);
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}
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uint8_t note = buffer[(*pos)++];
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if (note > 127 || buffer[(*pos)++] > 127) {
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raise_midi_stream_error(*pos);
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}
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return note;
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}
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STATIC void terminate_span(synthio_miditrack_obj_t *self, uint16_t *dur) {
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if (*dur) {
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self->track[self->total_spans - 1].dur = *dur;
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*dur = 0;
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} else {
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self->total_spans--;
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}
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}
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STATIC void add_span(synthio_miditrack_obj_t *self, const synthio_midi_span_t *span) {
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self->track = m_realloc(self->track,
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(self->total_spans + 1) * sizeof(synthio_midi_span_t));
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self->track[self->total_spans++] = *span;
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}
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STATIC int find_channel_with_note(const synthio_midi_span_t *span, uint8_t note) {
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for (int i = 0; i < CIRCUITPY_SYNTHIO_MAX_CHANNELS; i++) {
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if (span->note[i] == note) {
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return i;
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}
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}
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return -1;
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}
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STATIC void change_span_note(synthio_miditrack_obj_t *self, uint8_t old_note, uint8_t new_note, uint16_t *dur) {
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synthio_midi_span_t span = self->track[self->total_spans - 1];
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int channel = find_channel_with_note(&span, old_note);
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if (channel != -1) {
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terminate_span(self, dur);
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span.note[channel] = new_note;
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add_span(self, &span);
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*dur = 0;
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}
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}
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void common_hal_synthio_miditrack_construct(synthio_miditrack_obj_t *self,
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const uint8_t *buffer, uint32_t len, uint32_t tempo, uint32_t sample_rate) {
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synthio_midi_span_t initial = { 0, {[0 ... (CIRCUITPY_SYNTHIO_MAX_CHANNELS - 1)] = SILENCE} };
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self->sample_rate = sample_rate;
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self->track = m_malloc(sizeof(synthio_midi_span_t), false);
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self->next_span = 0;
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self->total_spans = 1;
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*self->track = initial;
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uint16_t dur = 0;
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uint32_t pos = 0;
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while (pos < len) {
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uint8_t c;
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uint32_t delta = 0;
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do {
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c = buffer[pos++];
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delta <<= 7;
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delta |= c & 0x7f;
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} while ((c & 0x80) && (pos < len));
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if (c & 0x80) {
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raise_midi_stream_error(pos);
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}
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// dur is carried over here so that if a note on/off message doesn't actually produce a change, the
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// underlying "span" is extended. Otherwise, it is zeroed out in the call to `terminate_span`.
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dur += delta * sample_rate / tempo;
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switch (buffer[pos++] >> 4) {
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case 8: { // Note Off
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uint8_t note = parse_note(buffer, len, &pos);
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change_span_note(self, note, SILENCE, &dur);
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break;
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}
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case 9: { // Note On
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uint8_t note = parse_note(buffer, len, &pos);
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change_span_note(self, SILENCE, note, &dur);
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break;
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}
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case 10:
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case 11:
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case 14: // two data bytes to ignore
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parse_note(buffer, len, &pos);
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break;
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case 12:
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case 13: // one data byte to ignore
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if (pos >= len || buffer[pos++] > 127) {
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raise_midi_stream_error(pos);
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}
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break;
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case 15: // the full syntax is too complicated, just assume it's "End of Track" event
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pos = len;
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break;
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default: // invalid event
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raise_midi_stream_error(pos);
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}
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}
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terminate_span(self, &dur);
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uint16_t max_dur = 0;
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for (int i = 0; i < self->total_spans; i++) {
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max_dur = MAX(self->track[i].dur, max_dur);
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}
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self->buffer_length = MIN(MAX_DUR, max_dur) * BYTES_PER_SAMPLE;
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self->buffer = m_malloc(self->buffer_length, false);
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}
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void common_hal_synthio_miditrack_deinit(synthio_miditrack_obj_t *self) {
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m_free(self->buffer);
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self->buffer = NULL;
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m_free(self->track);
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self->track = NULL;
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}
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bool common_hal_synthio_miditrack_deinited(synthio_miditrack_obj_t *self) {
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return self->buffer == NULL;
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}
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uint32_t common_hal_synthio_miditrack_get_sample_rate(synthio_miditrack_obj_t *self) {
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return self->sample_rate;
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}
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uint8_t common_hal_synthio_miditrack_get_bits_per_sample(synthio_miditrack_obj_t *self) {
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return BITS_PER_SAMPLE;
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}
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uint8_t common_hal_synthio_miditrack_get_channel_count(synthio_miditrack_obj_t *self) {
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return 1;
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}
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void synthio_miditrack_reset_buffer(synthio_miditrack_obj_t *self,
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bool single_channel_output, uint8_t channel) {
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self->remaining_dur = 0;
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self->next_span = 0;
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}
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STATIC const uint16_t notes[] = {8372, 8870, 9397, 9956, 10548, 11175, 11840,
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12544, 13290, 14080, 14917, 15804}; // 9th octave
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static int count_active_channels(synthio_midi_span_t *span) {
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int result = 0;
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for (int i = 0; i < CIRCUITPY_SYNTHIO_MAX_CHANNELS; i++) {
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if (span->note[i] != SILENCE) {
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result += 1;
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}
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}
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return result;
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}
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audioio_get_buffer_result_t synthio_miditrack_get_buffer(synthio_miditrack_obj_t *self,
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bool single_channel_output, uint8_t channel, uint8_t **buffer, uint32_t *buffer_length) {
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synthio_midi_span_t span = self->track[self->next_span - !!self->remaining_dur];
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if (self->remaining_dur == 0) {
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if (self->next_span >= self->total_spans) {
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*buffer_length = 0;
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return GET_BUFFER_DONE;
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}
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self->next_span++;
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self->remaining_dur = span.dur;
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}
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uint16_t dur = MIN(MAX_DUR, self->remaining_dur);
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self->remaining_dur -= dur;
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*buffer_length = dur * BYTES_PER_SAMPLE;
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memset(self->buffer, 0, *buffer_length);
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int32_t sample_rate = self->sample_rate;
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int active_channels = count_active_channels(&span);
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if (active_channels) {
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int16_t loudness = 0x3fff / (1 + active_channels);
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for (int chan = 0; chan < CIRCUITPY_SYNTHIO_MAX_CHANNELS; chan++) {
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if (span.note[chan] == SILENCE) {
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self->accum[chan] = 0;
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continue;
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}
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uint8_t octave = span.note[chan] / 12;
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uint16_t base_freq = notes[span.note[chan] % 12];
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uint32_t accum = self->accum[chan];
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uint32_t rate = base_freq * 2;
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for (uint16_t i = 0; i < dur; i++) {
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accum += rate;
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int16_t semiperiod = (accum / sample_rate) >> (10 - octave);
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self->buffer[i] += semiperiod % 2 ? loudness : -loudness;
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}
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self->accum[chan] = accum;
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}
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}
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*buffer = (uint8_t *)self->buffer;
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return (self->remaining_dur == 0 && self->next_span >= self->total_spans) ?
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GET_BUFFER_DONE : GET_BUFFER_MORE_DATA;
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}
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void synthio_miditrack_get_buffer_structure(synthio_miditrack_obj_t *self, bool single_channel_output,
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bool *single_buffer, bool *samples_signed, uint32_t *max_buffer_length, uint8_t *spacing) {
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*single_buffer = true;
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*samples_signed = true;
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*max_buffer_length = self->buffer_length;
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*spacing = 1;
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}
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