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/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2021 Artyom Skrobov
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "py/runtime.h"
#include "shared-bindings/synthio/MidiTrack.h"
#define LOUDNESS 0x4000 // 0.5
#define BITS_PER_SAMPLE 16
#define BYTES_PER_SAMPLE (BITS_PER_SAMPLE / 8)
#define SILENCE 0x80
STATIC uint8_t parse_note(const uint8_t *buffer, uint32_t len, uint32_t *pos) {
if (*pos + 1 >= len) {
mp_raise_ValueError_varg(translate("Error in MIDI stream at position %d"), *pos);
}
uint8_t note = buffer[(*pos)++];
if (note > 127 || buffer[(*pos)++] > 127) {
mp_raise_ValueError_varg(translate("Error in MIDI stream at position %d"), *pos);
}
return note;
}
STATIC void terminate_span(synthio_miditrack_obj_t *self, uint16_t *dur, uint16_t *max_dur) {
if (*dur) {
self->track[self->total_spans - 1].dur = *dur;
if (*dur > *max_dur) {
*max_dur = *dur;
}
*dur = 0;
} else {
self->total_spans--;
}
}
STATIC void add_span(synthio_miditrack_obj_t *self, uint8_t note1, uint8_t note2) {
synthio_midi_span_t span = { 0, {note1, note2} };
self->track = m_realloc(self->track,
(self->total_spans + 1) * sizeof(synthio_midi_span_t));
self->track[self->total_spans++] = span;
}
void common_hal_synthio_miditrack_construct(synthio_miditrack_obj_t *self,
const uint8_t *buffer, uint32_t len, uint32_t tempo, uint32_t sample_rate) {
synthio_midi_span_t initial = { 0, {SILENCE, SILENCE} };
self->sample_rate = sample_rate;
self->track = m_malloc(sizeof(synthio_midi_span_t), false);
self->next_span = 0;
self->total_spans = 1;
*self->track = initial;
uint16_t dur = 0, max_dur = 0;
uint32_t pos = 0;
while (pos < len) {
uint8_t c;
uint32_t delta = 0;
do {
c = buffer[pos++];
delta <<= 7;
delta |= c & 0x7f;
} while ((c & 0x80) && (pos < len));
if (c & 0x80) {
mp_raise_ValueError_varg(translate("Error in MIDI stream at position %d"), pos);
}
dur += delta * sample_rate / tempo;
switch (buffer[pos++] >> 4) {
case 8: { // Note Off
uint8_t note = parse_note(buffer, len, &pos);
// Ignore if not a note which is playing
synthio_midi_span_t last_span = self->track[self->total_spans - 1];
if (last_span.note[0] == note || last_span.note[1] == note) {
terminate_span(self, &dur, &max_dur);
if (last_span.note[0] == note) {
add_span(self, last_span.note[1], SILENCE);
} else {
add_span(self, last_span.note[0], SILENCE);
}
}
break;
}
case 9: { // Note On
uint8_t note = parse_note(buffer, len, &pos);
// Ignore if two notes are already playing
synthio_midi_span_t last_span = self->track[self->total_spans - 1];
if (last_span.note[1] == SILENCE) {
terminate_span(self, &dur, &max_dur);
if (last_span.note[0] == SILENCE) {
add_span(self, note, SILENCE);
} else {
add_span(self, last_span.note[0], note);
}
}
break;
}
case 10:
case 11:
case 14: // two data bytes to ignore
parse_note(buffer, len, &pos);
break;
case 12:
case 13: // one data byte to ignore
if (pos >= len || buffer[pos++] > 127) {
mp_raise_ValueError_varg(translate("Error in MIDI stream at position %d"), pos);
}
break;
case 15: // the full syntax is too complicated, just assume it's "End of Track" event
pos = len;
break;
default: // invalid event
mp_raise_ValueError_varg(translate("Error in MIDI stream at position %d"), pos);
}
}
terminate_span(self, &dur, &max_dur);
self->buffer_length = max_dur * BYTES_PER_SAMPLE;
self->buffer = m_malloc(self->buffer_length, false);
}
void common_hal_synthio_miditrack_deinit(synthio_miditrack_obj_t *self) {
m_free(self->buffer);
self->buffer = NULL;
m_free(self->track);
self->track = NULL;
}
bool common_hal_synthio_miditrack_deinited(synthio_miditrack_obj_t *self) {
return self->buffer == NULL;
}
uint32_t common_hal_synthio_miditrack_get_sample_rate(synthio_miditrack_obj_t *self) {
return self->sample_rate;
}
uint8_t common_hal_synthio_miditrack_get_bits_per_sample(synthio_miditrack_obj_t *self) {
return BITS_PER_SAMPLE;
}
uint8_t common_hal_synthio_miditrack_get_channel_count(synthio_miditrack_obj_t *self) {
return 1;
}
void synthio_miditrack_reset_buffer(synthio_miditrack_obj_t *self,
bool single_channel_output, uint8_t channel) {
self->next_span = 0;
}
STATIC const uint16_t notes[] = {8372, 8870, 9397, 9956, 10548, 11175, 11840,
12544, 13290, 14080, 14917, 15804}; // 9th octave
audioio_get_buffer_result_t synthio_miditrack_get_buffer(synthio_miditrack_obj_t *self,
bool single_channel_output, uint8_t channel, uint8_t **buffer, uint32_t *buffer_length) {
if (self->next_span >= self->total_spans) {
*buffer_length = 0;
return GET_BUFFER_DONE;
}
synthio_midi_span_t span = self->track[self->next_span++];
*buffer_length = span.dur * BYTES_PER_SAMPLE;
uint8_t octave1 = span.note[0] / 12; // 0..10
uint8_t octave2 = span.note[1] / 12; // 0..10
int32_t base_freq1 = notes[span.note[0] % 12];
int32_t base_freq2 = notes[span.note[1] % 12];
int32_t sample_rate = self->sample_rate;
for (uint16_t i = 0; i < span.dur; i++) {
int16_t semiperiod1 = span.note[0] == SILENCE ? 0 :
((base_freq1 * i * 2) / sample_rate) >> (10 - octave1);
int16_t semiperiod2 = span.note[1] == SILENCE ? semiperiod1 :
((base_freq2 * i * 2) / sample_rate) >> (10 - octave2);
self->buffer[i] = ((semiperiod1 % 2 + semiperiod2 % 2) - 1) * LOUDNESS;
}
*buffer = (uint8_t *)self->buffer;
return self->next_span >= self->total_spans ?
GET_BUFFER_DONE : GET_BUFFER_MORE_DATA;
}
void synthio_miditrack_get_buffer_structure(synthio_miditrack_obj_t *self, bool single_channel_output,
bool *single_buffer, bool *samples_signed, uint32_t *max_buffer_length, uint8_t *spacing) {
*single_buffer = true;
*samples_signed = true;
*max_buffer_length = self->buffer_length;
*spacing = 1;
}
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