160 lines
3.9 KiB
C++
160 lines
3.9 KiB
C++
/*
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Peacock-8 VA polysynth
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Copyright 2024 Gordon JC Pearce <gordonjcp@gjcp.net>
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "ic29.hpp"
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Synth ic29;
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Synth::Synth() {
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d_debug("initialising synth\n");
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envAtk = 0x007f;
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envDcy = envRls = 0xfe90;
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envStn = 0x1fff;
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portaCoeff = 0x0;
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}
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void Synth::buildTables(double sampleRate) {
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for (uint8_t i = 0; i < 104; i++) {
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// slightly flat middle C from ROM divider table
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// actually adjusted a little so that the notes are bang on
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// on the real synth the tuning knob is tweaked a little off to pull it in
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pitchTable[i] = 260.15f * powf(2, (i - 36) / 12.0f) / sampleRate;
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}
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}
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void Synth::run() {
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// handle a "loop" worth of envelopes, pitch calculations, etc
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// callled once every 4.3ms block of samples
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for (uint8_t i = 0; i < NUM_VOICES; i++) {
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ic29.voices[i].update();
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}
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}
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void Synth::voiceOn(uint8_t voice, uint8_t note) {
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// enable synth voice, start it all running
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voice &= 0x7f;
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ic29.voices[voice].on(note);
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}
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void Synth::voiceOff(uint8_t voice) {
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// enable synth voice, start it all running
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voice &= 0x7f;
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ic29.voices[voice].off();
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}
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void Synth::basePitch() {
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uint16_t pitch = 0x1818;
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pitch += lfoPitch;
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pitch += bendPitch;
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// tuning too but that's zero by default;
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masterPitch = pitch;
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}
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Envelope::Envelope() {
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level = 0;
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phase = ENV_IDLE;
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}
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void Envelope::run() {
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switch (phase) {
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case ENV_ATK:
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level += ic29.envAtk;
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if (level > 0x3fff) {
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level = 0x3fff;
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phase = ENV_DCY;
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}
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break;
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case ENV_DCY:
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if (level > ic29.envStn) {
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level -= ic29.envStn;
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level = (level * ic29.envDcy) >> 16;
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level += ic29.envStn;
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} else {
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level = ic29.envStn;
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}
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break;
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case ENV_RLS:
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level = (level * ic29.envRls) >> 16;
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break;
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case ENV_IDLE:
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default:
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break;
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}
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}
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Voice::Voice() {
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subosc = 1;
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}
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void Voice::calcPitch() {
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uint16_t target = note << 8;
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if (ic29.portaCoeff != 0) {
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// porta up
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if (pitch < target) {
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pitch += ic29.portaCoeff;
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if (pitch > target) pitch = target;
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}
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// porta down
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if (pitch > target) {
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pitch -= ic29.portaCoeff;
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if (pitch < target) pitch = target;
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}
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} else {
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pitch = target;
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}
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pitch += 0x1818; //ic29.masterPitch;
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if (pitch < 0x3000) pitch = 0x3000; // lowest note
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if (pitch > 0x9700) pitch = 0x6700; // highest note
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pitch -= 0x3000;
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//pitch &= 0xff00;
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double o1 = ic29.pitchTable[pitch >> 8];
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double o2 = ic29.pitchTable[(pitch >> 8) + 1];
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double frac = (pitch & 0xff) / 255.0;
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omega = ((o2 - o1) * frac) + o1;
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}
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void Voice::update() {
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// calculate the once-per-block values
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env.run();
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calcPitch();
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// do filter values
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}
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void Voice::on(uint8_t key) {
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voiceState = V_ON;
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note = key;
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env.on();
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}
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void Voice::off() {
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// I need to rethink this bit FIXME
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voiceState = V_OFF;
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if (!ic29.sustained) {
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env.off();
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}
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}
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