66 lines
2.1 KiB
C
66 lines
2.1 KiB
C
#if defined(STFU_MAIN) && !defined(STFU_TROJKA)
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#define STFU_TROJKA
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#include "../../config.h"
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#include "../../envelope.c"
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#include "../../phaser.c"
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#define STFU_TROJKA_OP_COUNT 3
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/* https://multimed.org/student/eim/en/04-FM.pdf */
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// todo: A few more algorithm configurations.
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// todo: Other oscillators.
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struct stfu_trojka {
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struct stfu_phaser phasers[STFU_TROJKA_OP_COUNT];
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struct stfu_envelope envelopes[STFU_TROJKA_OP_COUNT];
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float gains[STFU_TROJKA_OP_COUNT]; // todo: Combine with indices?
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float freq_scales[STFU_TROJKA_OP_COUNT];
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float indices[STFU_TROJKA_OP_COUNT - 1]; /* 1 to 100 */
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float key_frequency;
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float feedback_gain; // todo: Separate gain for channels?
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float left_feedback, right_feedback;
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};
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static struct stfu_trojka stfu_sample_trojka(struct stfu_trojka synth,
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float buffer[static 2]) {
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for (int i = 0; i < STFU_TROJKA_OP_COUNT; ++i) {
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synth.phasers[i] = stfu_pump_phaser(synth.phasers[i]);
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synth.envelopes[i] = stfu_pump_envelope(synth.envelopes[i]);
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}
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float left_modulator_stack =
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synth.envelopes[1].v * synth.indices[1] *
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sinf(synth.phasers[1].v + synth.envelopes[0].v * synth.indices[0] *
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sinf(synth.phasers[0].v)) +
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synth.left_feedback * synth.feedback_gain;
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float right_modulator_stack = left_modulator_stack;
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synth.left_feedback = left_modulator_stack;
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synth.right_feedback = right_modulator_stack;
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float left =
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synth.envelopes[2].v * sinf(synth.phasers[2].v + left_modulator_stack);
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float right =
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synth.envelopes[2].v * sinf(synth.phasers[2].v + right_modulator_stack);
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buffer[0] = left;
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buffer[1] = right;
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return synth;
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}
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static struct stfu_trojka stfu_press_trojka(struct stfu_trojka synth,
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float key_frequency) {
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for (int i = 0; i < STFU_TROJKA_OP_COUNT; ++i) {
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synth.phasers[i] = stfu_set_phaser_frequency(
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synth.phasers[i], key_frequency * synth.freq_scales[i]);
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synth.envelopes[i] = stfu_trigger_envelope(synth.envelopes[i]);
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}
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return synth;
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}
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#endif
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