Add CVPort example

Signed-off-by: falkTX <falktx@falktx.com>

Makefile

@@ -20,6 +20,7 @@ dgl:
 	$(MAKE) -C dgl
 
 examples: dgl
+	$(MAKE) all -C examples/CVPort
 	$(MAKE) all -C examples/Info
 	$(MAKE) all -C examples/Latency
 	$(MAKE) all -C examples/Meters
@@ -60,6 +61,7 @@ tests: dgl
 
 clean:
 	$(MAKE) clean -C dgl
+	$(MAKE) clean -C examples/CVPort
 	$(MAKE) clean -C examples/CairoUI
 	$(MAKE) clean -C examples/Info
 	$(MAKE) clean -C examples/Latency

examples/CVPort/DistrhoPluginInfo.h

@@ -0,0 +1,30 @@
+/*
+ * DISTRHO Plugin Framework (DPF)
+ * Copyright (C) 2012-2021 Filipe Coelho <falktx@falktx.com>
+ *
+ * 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 DISTRHO_PLUGIN_INFO_H_INCLUDED
+#define DISTRHO_PLUGIN_INFO_H_INCLUDED
+
+#define DISTRHO_PLUGIN_BRAND "DISTRHO"
+#define DISTRHO_PLUGIN_NAME  "CVPort"
+#define DISTRHO_PLUGIN_URI   "http://distrho.sf.net/examples/CVPort"
+
+#define DISTRHO_PLUGIN_IS_RT_SAFE  1
+// NOTE: 1 of these is CV
+#define DISTRHO_PLUGIN_NUM_INPUTS  2
+// NOTE: CV output
+#define DISTRHO_PLUGIN_NUM_OUTPUTS 1
+
+#endif // DISTRHO_PLUGIN_INFO_H_INCLUDED

examples/CVPort/ExamplePluginCVPort.cpp

@@ -0,0 +1,272 @@
+/*
+ * DISTRHO Plugin Framework (DPF)
+ * Copyright (C) 2012-2021 Filipe Coelho <falktx@falktx.com>
+ *
+ * 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 "DistrhoPlugin.hpp"
+
+START_NAMESPACE_DISTRHO
+
+// -----------------------------------------------------------------------------------------------------------
+
+/**
+  Simple plugin to demonstrate how to modify input/output port type in DPF.
+  The plugin outputs sample & hold (S&H) value of input signal.
+  User can specify hold time via parameter and/or Hold Time CV port.
+ */
+class ExamplePluginCVPort : public Plugin
+{
+    static constexpr const float kMaxHoldTime = 1.0f;
+
+public:
+    ExamplePluginCVPort()
+        : Plugin(1, 0, 0), // 1 parameters, 0 programs, 0 states
+          counter(0),
+          holdTime(0.0f),
+          holdValue(0.0f),
+          sampleRate(getSampleRate()) {}
+
+protected:
+   /* --------------------------------------------------------------------------------------------------------
+    * Information */
+
+   /**
+      Get the plugin label.
+      A plugin label follows the same rules as Parameter::symbol, with the exception that it can start with numbers.
+    */
+    const char* getLabel() const override
+    {
+        return "CVPort";
+    }
+
+   /**
+      Get an extensive comment/description about the plugin.
+    */
+    const char* getDescription() const override
+    {
+        return "Simple plugin with CVPort.\nThe plugin does sample & hold processing.";
+    }
+
+   /**
+      Get the plugin author/maker.
+    */
+    const char* getMaker() const override
+    {
+        return "DISTRHO";
+    }
+
+   /**
+      Get the plugin homepage.
+    */
+    const char* getHomePage() const override
+    {
+        return "https://github.com/DISTRHO/DPF";
+    }
+
+   /**
+      Get the plugin license name (a single line of text).
+      For commercial plugins this should return some short copyright information.
+    */
+    const char* getLicense() const override
+    {
+        return "ISC";
+    }
+
+   /**
+      Get the plugin version, in hexadecimal.
+    */
+    uint32_t getVersion() const override
+    {
+        return d_version(1, 0, 0);
+    }
+
+   /**
+      Get the plugin unique Id.
+      This value is used by LADSPA, DSSI and VST plugin formats.
+    */
+    int64_t getUniqueId() const override
+    {
+        return d_cconst('d', 'C', 'V', 'P');
+    }
+
+   /* --------------------------------------------------------------------------------------------------------
+    * Init */
+
+   /**
+      Initialize the audio port @a index.@n
+      This function will be called once, shortly after the plugin is created.
+    */
+    void initAudioPort(bool input, uint32_t index, AudioPort& port) override
+    {
+       /**
+          Note that index is independent for input and output.
+          In other words, input port index starts from 0 and output port index also starts from 0.
+        */
+        if (input)
+        {
+            switch (index)
+            {
+            case 0:
+                // Audio port doesn't need to specify port.hints.
+                port.name    = "Audio Input";
+                port.symbol  = "audio_in";
+                return;
+            case 1:
+                port.hints   = kAudioPortIsCV;
+                port.name    = "Hold Time";
+                port.symbol  = "hold_time";
+                return;
+            }
+            // Add more conditions here when increasing DISTRHO_PLUGIN_NUM_INPUTS.
+        }
+        else
+        {
+            switch (index)
+            {
+            case 0:
+                port.hints   = kAudioPortIsCV;
+                port.name    = "CV Output";
+                port.symbol  = "cv_out";
+                return;
+            }
+            // Add more conditions here when increasing DISTRHO_PLUGIN_NUM_OUTPUTS.
+        }
+
+        // It shouldn't reach here, but just in case if index is greater than 0.
+        Plugin::initAudioPort(input, index, port);
+    }
+
+   /**
+      Initialize the parameter @a index.
+      This function will be called once, shortly after the plugin is created.
+    */
+    void initParameter(uint32_t index, Parameter& parameter) override
+    {
+        if (index != 0)
+            return;
+
+        parameter.name       = "Hold Time";
+        parameter.symbol     = "hold_time";
+        parameter.hints      = kParameterIsAutomable|kParameterIsLogarithmic;
+        parameter.ranges.min = 0.0f;
+        parameter.ranges.max = kMaxHoldTime;
+        parameter.ranges.def = 0.1f;
+    }
+
+   /* --------------------------------------------------------------------------------------------------------
+    * Internal data */
+
+   /**
+      Get the current value of a parameter.
+    */
+    float getParameterValue(uint32_t index) const override
+    {
+        if (index != 0)
+            return 0.0f;
+
+        return holdTime;
+    }
+
+   /**
+      Change a parameter value.
+    */
+    void setParameterValue(uint32_t index, float value) override
+    {
+        if (index != 0)
+            return;
+
+        holdTime = value;
+        counter = uint32_t(holdTime * sampleRate);
+    }
+
+   /* --------------------------------------------------------------------------------------------------------
+    * Process */
+
+   /**
+      Run/process function for plugins without MIDI input.
+    */
+    void run(const float** inputs, float** outputs, uint32_t frames) override
+    {
+        float cv, time;
+
+       /**
+        - inputs[0] is input audio port.
+        - inputs[1] is hold time CV port.
+        - outputs[0] is output CV port.
+        */
+       const float* const audioIn = inputs[0];
+       const float* const holdCV = inputs[1];
+       float* const cvOut = outputs[0];
+
+        for (uint32_t i = 0; i < frames; ++i)
+        {
+            if (counter == 0)
+            {
+                cv = holdCV[i] > 0.0f ? holdCV[i] : 0.0f;
+
+                time = holdTime + cv;
+                if (time > kMaxHoldTime)
+                    time = kMaxHoldTime;
+
+                counter = static_cast<uint32_t>(time * sampleRate + 0.5f);
+
+                holdValue = audioIn[i]; // Refresh hold value.
+            }
+            else
+            {
+                --counter;
+            }
+
+            cvOut[i] = holdValue;
+        }
+    }
+
+   /* --------------------------------------------------------------------------------------------------------
+    * Callbacks (optional) */
+
+   /**
+      Optional callback to inform the plugin about a sample rate change.@n
+      This function will only be called when the plugin is deactivated.
+    */
+    void sampleRateChanged(double newSampleRate) override
+    {
+        sampleRate = newSampleRate;
+        counter = static_cast<uint32_t>(holdTime * sampleRate + 0.5f);
+    }
+
+    // -------------------------------------------------------------------------------------------------------
+
+private:
+    uint32_t counter; // Hold time in samples. Used to count hold time.
+    float holdTime;  // Hold time in seconds.
+    float holdValue;
+    float sampleRate;
+
+   /**
+      Set our plugin class as non-copyable and add a leak detector just in case.
+    */
+    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(ExamplePluginCVPort)
+};
+
+/* ------------------------------------------------------------------------------------------------------------
+ * Plugin entry point, called by DPF to create a new plugin instance. */
+
+Plugin* createPlugin()
+{
+    return new ExamplePluginCVPort();
+}
+
+// -----------------------------------------------------------------------------------------------------------
+
+END_NAMESPACE_DISTRHO

examples/CVPort/Makefile

@@ -0,0 +1,34 @@
+#!/usr/bin/make -f
+# Makefile for DISTRHO Plugins #
+# ---------------------------- #
+# Created by falkTX
+#
+
+# --------------------------------------------------------------
+# Project name, used for binaries
+
+NAME = d_cvport
+
+# --------------------------------------------------------------
+# Files to build
+
+FILES_DSP = \
+	ExamplePluginCVPort.cpp
+
+# --------------------------------------------------------------
+# Do some magic
+
+include ../../Makefile.plugins.mk
+
+# --------------------------------------------------------------
+# Enable all possible plugin types
+
+ifeq ($(HAVE_JACK),true)
+TARGETS += jack
+endif
+
+TARGETS += lv2_dsp
+
+all: $(TARGETS)
+
+# --------------------------------------------------------------

examples/CVPort/README.md

@@ -0,0 +1,16 @@
+# CVPort example
+
+This example will show how to modify audio input/output port type in DPF so they can work as CV.<br/>
+Take a look at `initAudioPort()` method.<br/>
+
+Worth noting that CV is not supported outside of JACK and LV2 formats.<br/>
+While it can be built and used in other formats, these ports will appear as regular audio to the host.
+
+The plugin does sample & hold (S&H) processing.<br/>
+3 I/O ports are specified.<br/>
+
+- Input audio port.
+- Input CV port to modify Hold Time.
+- Output CV port.
+
+The plugin also has a Hold Time parameter. It mixes CV value and parameter value.<br/>