91 lines
2.1 KiB
C
91 lines
2.1 KiB
C
#include "sust.h"
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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void sust_init(struct sust* sust)
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{
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sust->mode = MODE_Sostenuto;
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sust->playing = false;
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sust->start_idx = 0;
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sust->idx = 0;
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sust->buf_len = 51200;
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sust->record_buf = malloc(sizeof(float) * sust->buf_len);
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sust->play_buf = malloc(sizeof(float) * sust->buf_len);
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}
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float envelope(float x)
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{
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if (x < 0.4)
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return (x / 0.4) * (x / 0.4);
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if (x < 0.6)
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return 1.0;
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float v = 1.0 - ((x - 0.6) / 0.4);
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return v * v;
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}
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float softcos(float x)
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{
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return sin(x * (3.141 / 2.0));
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}
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void sust_resize(struct sust* sust, size_t new_len)
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{
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sust->buf_len = new_len;
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sust->play_buf = realloc(sust->play_buf, sizeof(float) * new_len);
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sust->record_buf = realloc(sust->record_buf, sizeof(float) * new_len);
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sust->idx %= new_len;
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}
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void sust_swap(
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struct sust* sust)
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{
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float* tmp = sust->play_buf;
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sust->play_buf = sust->record_buf;
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sust->record_buf = tmp;
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for (int i = 0; i < sust->buf_len; ++i) {
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sust->record_buf[i] = sust->play_buf[i];
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}
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}
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void sust_process(
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struct sust* sust,
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size_t frame_size,
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float const* in,
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float* out)
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{
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for (size_t i = 0; i < frame_size; ++i) {
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if (sust->mode == MODE_Sustain && sust->idx == 0) {
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sust_swap(sust);
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}
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float out_value = in[i];
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if (sust->playing) {
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int n_voices = 5;
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for (int v = 0; v < n_voices; ++v) {
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size_t play_idx = (sust->start_idx + sust->idx + ((v * sust->buf_len) / n_voices)) % sust->buf_len;
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float gain = envelope(((float)play_idx) / ((float)sust->buf_len));
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// printf("gain = %f\n", gain);
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out_value += 0.5 * gain * sust->play_buf[play_idx];
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}
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}
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if (sust->mode == MODE_Sostenuto) {
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sust->record_buf[sust->idx] = in[i];
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}
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if (sust->mode == MODE_Sustain) {
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sust->record_buf[sust->idx] = 0.5 * out_value;
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}
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sust->idx = (sust->idx + 1) % sust->buf_len;
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out[i] = out_value;
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}
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}
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