Adding Flanger FX -> 1 point to fix as code is not compiling

src/Makefile

@@ -10,7 +10,7 @@ OBJS = main.o kernel.o minidexed.o config.o userinterface.o uimenu.o \
        mididevice.o midikeyboard.o serialmididevice.o pckeyboard.o \
        sysexfileloader.o performanceconfig.o perftimer.o \
        effect_compressor.o effect_platervbstereo.o \
-       fx.o fx_orbitone.o fx_phaser.o fx_tape_delay.o fx_shimmer_reverb.o fx_rack.o \
+       fx.o fx_flanger.o fx_orbitone.o fx_phaser.o fx_tape_delay.o fx_shimmer_reverb.o fx_rack.o \
        uibuttons.o midipin.o
 
 OPTIMIZE = -O3

src/fx_flanger.cpp

@@ -0,0 +1,101 @@
+#include "fx_flanger.h"
+
+#include <cmath>
+
+#define MAX_FLANGER_DELAY 20.0f
+
+Flanger::Flanger(float32_t sampling_rate, float32_t delay_time, float32_t frequency, float32_t depth, float32_t feedback) :
+    FXElement(sampling_rate),
+    MaxDelayLineSize(static_cast<unsigned>(MAX_FLANGER_DELAY * sampling_rate / 1000.0f)),
+    lfo_phase_(0.0f)
+{
+    this->delay_lineL_ = new float32_t[this->MaxDelayLineSize];
+    this->delay_lineR_ = new float32_t[this->MaxDelayLineSize];
+
+    this->setDelayTime(delay_time);
+    this->setFrequency(frequency);
+    this->setDepth(depth);
+    this->setFeedback(feedback);
+}
+
+Flanger::~Flanger()
+{
+    delete[] this->delay_lineL_;
+    delete[] this->delay_lineR_;
+}
+
+void Flanger::processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR)
+{
+    // Modulate the delay time using the LFO
+    float32_t delay = this->delay_time_ms_ + this->depth_ * sin(this->lfo_phase_);
+
+    // Calculate the delay line index and interpolate between samples
+    int index = (i - (int) (this->getSamplingRate() * delay / 1000.0f)) % this->delay_line_size_;
+    float32_t frac = (this->getSamplingRate() * delay / 1000.0f) - (int) (this->getSamplingRate() * delay / 1000.0f);
+    float32_t x1 = this->delay_lineL_[index];
+    float32_t x2 = this->delay_lineL_[(index + 1) % this->delay_line_size_];
+    float32_t sample = x1 + frac * (x2 - x1);
+
+    // Process the input sample through the flanger
+    outL = inL + sample * this->feedback_;
+    outR = inR + sample * this->feedback_;
+
+    // Update the delay line
+    this->delay_lineL_[i % this->delay_line_size_] = outL;
+    this->delay_lineR_[i % this->delay_line_size_] = outR;
+
+    // Update the phase of the LFO
+    this->lfo_phase_ += this->lfo_phase_increment_;
+    if(this->lfo_phase_ > 2.0 * PI) {
+        this->lfo_phase_ -= 2.0 * PI;
+    }
+}
+
+void Flanger::setDelayTime(float32_t delayMS)
+{
+    this->delay_time_ms_ = constrain(delayMS, 1.0f, 10.0f);
+    this->adjustDelayCofficients();
+}
+
+float32_t Flanger::getDelayTime() const
+{
+    return this->delay_time_ms_;
+}
+
+void Flanger::setFrequency(float32_t frequency)
+{
+    frequency = constrain(frequency, 0.1f, 1.0f);
+    this->frequency_ = frequency;
+    this->lfo_phase_increment_ = 2.0f * PI * frequency / this->getSamplingRate();
+}
+
+float32_t Flanger::getFrequency() const
+{
+    return this->frequency_;
+}
+
+void Flanger::setDepth(float32_t depth)
+{
+    this->depth_ = constrain(depth, 0.0f, 10.0f);
+    this->adjustDelayCofficients();
+}
+
+float32_t Flanger::getDepth() const
+{
+    return this->depth_;
+}
+
+void Flanger::setFeedback(float32_t feedback)
+{
+    this->feedback_ = constrain(feedback, 0.0f, 1.0f);
+}
+
+float32_t Flanger::getFeedback() const
+{
+    return this->feedback_;
+}
+
+void Flanger::adjustDelayCofficients()
+{
+    this->delay_line_size_ = static_cast<unsigned>(this->getSamplingRate() * (this->getDelayTime() + this->getDepth()) / 1000.0f);
+}

src/fx_flanger.h

@@ -0,0 +1,60 @@
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//
+// fx_flanger.h
+//
+// Stereo Flanger audio effects proposed in the context of the MiniDexed project
+//
+#pragma once
+
+#include "fx.h"
+
+class Flanger : public FXElement
+{
+    DISALLOW_COPY_AND_ASSIGN(Flanger);
+
+public:
+    Flanger(float32_t sampling_rate, float32_t delay_time = 5.0f, float32_t frequency = 0.5f, float32_t depth = 1.0f, float32_t feedback = 0.5f);
+    virtual ~Flanger();
+
+    virtual void processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR) override;
+
+    void setDelayTime(float32_t delayMS);
+    inline float32_t getDelayTime() const;
+
+    void setFrequency(float32_t frequency);
+    inline float32_t getFrequency() const;
+
+    void setDepth(float32_t depth);
+    inline float32_t getDepth() const;
+
+    void setFeedback(float32_t feedback);
+    inline float32_t getFeedback() const;
+
+private:
+    inline void adjustDelayCofficients();
+
+    const unsigned MaxDelayLineSize;
+    unsigned delay_line_size_;
+    float32_t* delay_lineL_;
+    float32_t* delay_lineR_;
+
+    float32_t lfo_phase_;
+    float32_t lfo_phase_increment_;
+
+    float32_t delay_time_ms_;   // Delay time in milliseconds
+    float32_t frequency_;       // LFO frequency in HZ (0.1 - 10.0)
+    float32_t depth_;           // Depth of the flanger effect in milliseconds
+    float32_t feedback_;        // Amount of feedback to apply to the delay line
+};