generates sine tones

plugin/Makefile

@@ -9,7 +9,7 @@
 
 NAME = tonewheel
 
-FILES_DSP = assigner.cpp tonewheel.cpp
+FILES_DSP = generator.cpp assigner.cpp tonewheel.cpp
 include ../dpf/Makefile.plugins.mk
 
 TARGETS += vst2 vst3 jack lv2_dsp

plugin/assigner.cpp

@@ -18,7 +18,7 @@
 
 #include "assigner.hpp"
 
-#define DEBUG
+//#define DEBUG
 
 void Assigner::dumpTables() {
 #ifdef DEBUG
@@ -32,7 +32,7 @@ void Assigner::dumpTables() {
 #endif
 }
 
-Assigner::Assigner() {
+Assigner::Assigner(Voice *v) {
     d_debug("assigner constructor");
 
     // set up the assigner tables
@@ -40,6 +40,9 @@ Assigner::Assigner() {
         voiceTbl[i] = i;
         noteTbl[i] = 0x80;
     }
+
+    // populate the pointer to the generator voice table
+    voices = v;
 }
 
 void Assigner::handleMidi(MidiEvent *ev) {
@@ -92,6 +95,7 @@ void Assigner::noteOff(uint8_t note) {
     memmove(voiceTbl + i, voiceTbl + i + 1, NUM_VOICES - i - 1);
     voiceTbl[NUM_VOICES - 1] = v;
     noteTbl[v] |= 0x80;
+    voices[v].stopNote();
 }
 
 void Assigner::noteOn(uint8_t note) {
@@ -137,5 +141,6 @@ void Assigner::noteOn(uint8_t note) {
     while(note>96) note -= 12;
     while(note<36) note += 12;
 
+    voices[v].startNote(note);
     d_debug("send voice on note %3d to voice %d", note, v);
 }

plugin/assigner.hpp

@@ -20,10 +20,11 @@
 #define _ASSIGNER_HPP
 
 #include "DistrhoPlugin.hpp"
+#include "generator.hpp"
 
 class Assigner {
    public:
-    Assigner();
+    Assigner(Voice *v);
     void handleMidi(MidiEvent *ev);
 
    private:
@@ -33,6 +34,7 @@ class Assigner {
 
     uint8_t voiceTbl[NUM_VOICES];  // voices in order of use
     uint8_t noteTbl[NUM_VOICES];   // note played by voice
+    Voice *voices;
 };
 
 #endif

plugin/generator.cpp

@@ -0,0 +1,92 @@
+/*
+   tonewheel organ plugin
+
+   Copyright 2025 Gordon JC Pearce <gordonjcp@gjcp.net>
+
+   Permission to use, copy, modify, and/or distribute this software for any
+   purpose with or without fee is hereby granted, provided that the above
+   copyright notice and this permission notice appear in all copies.
+
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+   SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+   OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "generator.hpp"
+
+#include <math.h>
+#include <string.h>
+
+#include <cstdio>
+
+#include "DistrhoPluginInfo.h"
+
+// globals set when the plugin is activated
+// sample rate or buffer size may actually change!
+extern double sampleRate;
+extern uint32_t bufferSize;
+
+Generator::Generator() {
+}
+
+Generator::~Generator() {
+}
+
+void Generator::activate() {
+    // create a sine table
+    for (uint16_t i = 0; i < 256; i++) {
+        sine[i] = sin((float)i / 128.0 * 3.14159);
+    }
+    // create the phase increments for each semitone
+    for (uint8_t i = 0; i < 12; i++) {
+        phase[i] = 0;
+        uint32_t f;
+        f = (1 << 30) * (32.703 * powf(2, 0.083334 * i) / sampleRate);
+        omega[i] = f;
+    }
+}
+
+void Generator::run(float *output, uint32_t frames) {
+    Voice *v;
+    uint32_t i;
+    uint8_t k, p;
+    uint32_t d = 0;
+
+    memset(output, 0, frames * sizeof(float));
+
+    // for every frame of the output...
+    for (i = 0; i < frames; i++) {
+        // loop over all twelve semitones adding on the phase increment
+        // these are 32-bit unsigned values and will wrap
+        for (p = 0; p < 12; p++) {
+            phase[p] += omega[p];
+        }
+
+        // loop over all the voices, calculating what they need
+        for (k = 0; k < NUM_VOICES; k++) {
+            v = &voices[k];
+
+            // 8' stop
+            d = (phase[v->semi] >> (24 - v->oct)) & 0xff;
+            output[i] += .25 * (sine[d] * v->gate);
+
+            // mutation stops are a fifth up
+            d = (phase[(v->semi + 7) % 12] >> (22 - v->oct)) & 0xff;
+            output[i] += .25 * (sine[d] * v->gate);
+        }
+    }
+}
+
+void Voice::startNote(uint8_t key) {
+    // start a new note
+    semi = key % 12, oct = (key / 12);
+    gate = 1;
+}
+
+void Voice::stopNote() {
+    gate = 0;
+}

plugin/generator.hpp

@@ -0,0 +1,56 @@
+/*
+   tonewheel organ plugin
+
+   Copyright 2025 Gordon JC Pearce <gordonjcp@gjcp.net>
+
+   Permission to use, copy, modify, and/or distribute this software for any
+   purpose with or without fee is hereby granted, provided that the above
+   copyright notice and this permission notice appear in all copies.
+
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+   SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+   OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef GENERATOR_HPP
+#define GENERATOR_HPP
+
+#include <stdint.h>
+
+#include "DistrhoPluginInfo.h"
+
+class Generator;
+
+class Voice {
+    friend Generator;
+
+   public:
+    void startNote(uint8_t key);
+    void stopNote();
+
+   private:
+    uint8_t semi, oct;
+    float gate;
+};
+
+class Generator {
+   public:
+    // Generator(uint32_t bufferSize, double xSampleRate);
+    Generator();
+
+    ~Generator();
+    void run(float *output, uint32_t frames);
+    void activate();
+    Voice voices[NUM_VOICES];
+
+   private:
+    uint32_t phase[12];
+    uint32_t omega[12];
+    float sine[256];
+};
+
+#endif

plugin/tonewheel.cpp

@@ -24,11 +24,15 @@ uint32_t bufferSize;
 START_NAMESPACE_DISTRHO
 
 Tonewheel::Tonewheel() : Plugin(kParameterCount, 0, 0) {
-    assigner = new Assigner;
+    generator = new Generator;
+    assigner = new Assigner(generator->voices);
+    printf("Tonewheel constructor\n");
 }
 
 Tonewheel::~Tonewheel() {
     delete assigner;
+    delete generator;
+    printf("Tonewheel destructor\n");
 }
 
 void Tonewheel::initAudioPort(bool input, uint32_t index, AudioPort& port) {
@@ -42,6 +46,7 @@ void Tonewheel::initAudioPort(bool input, uint32_t index, AudioPort& port) {
 void Tonewheel::activate() {
     sampleRate = getSampleRate();
     bufferSize = getBufferSize();
+    generator->activate();
     printf("In activate, bufSz=%d smpRt=%f\n", bufferSize, sampleRate);
 }
 
@@ -51,11 +56,11 @@ void Tonewheel::deactivate() {
 void Tonewheel::run(const float**, float** outputs, uint32_t frames,
                     const MidiEvent* ev, uint32_t evCount) {
 
-    (void) frames;
-    (void) outputs;
     for (uint32_t i = 0; i < evCount; i++) {
         assigner->handleMidi((MidiEvent*)&ev[i]);
     }
+
+    generator->run(outputs[0], frames);
 }
 
 Plugin* createPlugin() { return new Tonewheel(); }

plugin/tonewheel.hpp

@@ -65,6 +65,7 @@ class Tonewheel : public Plugin {
 
     private:
     Assigner *assigner;
+    Generator *generator;
 
     DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(Tonewheel);
 };