95 lines
2.7 KiB
C++
95 lines
2.7 KiB
C++
/*
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tonewheel organ plugin
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Copyright 2025 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 "generator.hpp"
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#include <math.h>
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#include <string.h>
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#include <cstdio>
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#include "DistrhoPluginInfo.h"
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// globals set when the plugin is activated
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// sample rate or buffer size may actually change!
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extern double sampleRate;
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extern uint32_t bufferSize;
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Generator::Generator() {
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}
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Generator::~Generator() {
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}
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void Generator::activate() {
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// create a sine table
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for (uint16_t i = 0; i < 256; i++) {
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sine[i] = sin((float)i / 128.0 * 3.14159);
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}
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// create the phase increments for each semitone
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for (uint8_t i = 0; i < 12; i++) {
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phase[i] = 0;
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uint32_t f;
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f = (1 << 30) * (32.703 * powf(2, 0.083334 * i) / sampleRate);
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omega[i] = f;
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}
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}
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void Generator::run(float *output, uint32_t frames) {
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Voice *v;
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uint32_t i;
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uint8_t k, p;
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uint32_t d = 0;
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memset(output, 0, frames * sizeof(float));
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// for every frame of the output...
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for (i = 0; i < frames; i++) {
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// loop over all twelve semitones adding on the phase increment
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// these are 32-bit unsigned values and will wrap
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for (p = 0; p < 12; p++) {
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phase[p] += omega[p];
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}
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// loop over all the voices, calculating what they need
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for (k = 0; k < NUM_VOICES; k++) {
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v = &voices[k];
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// you'd loop over all the stops in the register here
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// 8' stop
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d = (phase[v->semi] >> (24 - v->oct)) & 0xff;
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// convert to a sine and scale it by 0.25, which would want to be your drawbar amount
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output[i] += .25 * (sine[d] * v->gate);
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// mutation stops are a fifth up
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d = (phase[(v->semi + 7) % 12] >> (22 - v->oct)) & 0xff;
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output[i] += .25 * (sine[d] * v->gate);
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}
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}
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}
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void Voice::startNote(uint8_t key) {
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// start a new note
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semi = key % 12, oct = (key / 12);
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gate = 1;
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}
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void Voice::stopNote() {
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gate = 0;
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}
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