6 files changed, 79 insertions, 0 deletions
diff --git a/src/DSP/Delay.cpp b/src/DSP/Delay.cpp
new file mode 100644
index 0000000..50c310a
--- /dev/null
+++ b/src/DSP/Delay.cpp
@@ -0,0 +1,37 @@
+#include "Delay.h"
+
+void
+Delay::prepare(double sampleRate, int samplesPerBlock)
+{
+    int maxDelayTimeMs = 2000;
+    int maxDelaySamples = static_cast<int>(sampleRate * maxDelayTimeMs / 1000.0);
+
+    delayBuffer.resize(maxDelaySamples, 0.0f);
+    std::fill(delayBuffer.begin(), delayBuffer.end(), 0.0f);
+    delayBufferWritePos = 0;
+    this->sampleRate = sampleRate;
+}
+
+void
+Delay::process(float& sample)
+{
+    if (delayInSamples == 0)
+    {
+        return;
+    }
+    int delayBufferLength = (int)delayBuffer.size();
+    int delayReadPos
+        = (delayBufferWritePos - delayInSamples + delayBufferLength) % delayBufferLength;
+    float delayedSample = delayBuffer[delayReadPos];
+
+    delayBuffer[delayBufferWritePos] = sample;
+    sample = delayedSample;
+
+    delayBufferWritePos = (delayBufferWritePos + 1) % delayBufferLength;
+}
+
+void
+Delay::setDelayMs(float ms)
+{
+    delayInSamples = static_cast<int>(sampleRate * (ms / 1000.0f));
+}
diff --git a/src/DSP/Delay.h b/src/DSP/Delay.h
new file mode 100644
index 0000000..e8bd2f1
--- /dev/null
+++ b/src/DSP/Delay.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <juce_audio_processors/juce_audio_processors.h>
+
+class Delay
+{
+  public:
+    void prepare(double sampleRate, int samplesPerBlock);
+    void reset();
+    void process(float& sample);
+    void setDelayMs(float ms);
+
+  private:
+    std::vector<float> delayBuffer;
+    int delayBufferWritePos = 0;
+    int delayInSamples = 0;
+    double sampleRate = 0.0;
+};
diff --git a/src/DSP/SchroederReverb.cpp b/src/DSP/SchroederReverb.cpp
index 1b84712..87aa3c4 100644
--- a/src/DSP/SchroederReverb.cpp
+++ b/src/DSP/SchroederReverb.cpp
@@ -19,6 +19,7 @@ SchroederReverb::process(float& sample, float dryWetMix, float decayFactor)
 
     float in = sample;
 
+    preDelay.process(in);
 
     float cf0in = in;
     float cf1in = in;
@@ -36,3 +37,9 @@ SchroederReverb::process(float& sample, float dryWetMix, float decayFactor)
 
     sample = dryWetMix * allPassIn + (1.0f - dryWetMix) * sample;
 }
+
+void
+SchroederReverb::setPreDelayMs(float ms)
+{
+    preDelay.setDelayMs(ms);
+}
diff --git a/src/DSP/SchroederReverb.h b/src/DSP/SchroederReverb.h
index 2d5cd0b..5f1b7b1 100644
--- a/src/DSP/SchroederReverb.h
+++ b/src/DSP/SchroederReverb.h
@@ -2,6 +2,7 @@
 
 #include "AllPassFilter.h"
 #include "CombFilter.h"
+#include "Delay.h"
 #include <juce_audio_processors/juce_audio_processors.h>
 
 class SchroederReverb
@@ -11,7 +12,10 @@ class SchroederReverb
     void reset();
     void process(float& sample, float dryWetMix, float decayFactor);
 
+    void setPreDelayMs(float ms);
+
   private:
     CombFilter combFilter0, combFilter1, combFilter2, combFilter3;
     AllPassFilter allPassFilter0, allPassFilter1;
+    Delay preDelay;
 };
diff --git a/src/PluginProcessor.cpp b/src/PluginProcessor.cpp
index f10065f..768dda0 100644
--- a/src/PluginProcessor.cpp
+++ b/src/PluginProcessor.cpp
@@ -9,6 +9,8 @@ SchroederReverbAudioProcessor::SchroederReverbAudioProcessor()
 {
     addParameter(dryWetMix = new juce::AudioParameterFloat("mix", "Mix", 0.0f, 1.0f, 0.5f));
     addParameter(decayFactor = new juce::AudioParameterFloat("decay", "Decay", 0.1f, 10.0f, 1.0f));
+    addParameter(preDelay
+                 = new juce::AudioParameterFloat("predelay", "Pre-Delay", 0.0f, 0.2f, 0.0f));
 }
 
 SchroederReverbAudioProcessor::~SchroederReverbAudioProcessor() {}
@@ -104,6 +106,13 @@ SchroederReverbAudioProcessor::processBlock(juce::AudioBuffer<float>& buffer,
     int totalNumInputChannels = getTotalNumInputChannels();
     int totalNumOutputChannels = getTotalNumOutputChannels();
 
+    float currentPreDelay = preDelay->get();
+    if (currentPreDelay != lastPreDelay)
+    {
+      schroederReverb.setPreDelayMs(currentPreDelay * 1000.0f);
+        lastPreDelay = currentPreDelay;
+    }
+
     // Clear extra channels
     for (int i = totalNumInputChannels; i < totalNumOutputChannels; ++i)
         buffer.clear(i, 0, buffer.getNumSamples());
diff --git a/src/PluginProcessor.h b/src/PluginProcessor.h
index f6e6f5d..00b18d0 100644
--- a/src/PluginProcessor.h
+++ b/src/PluginProcessor.h
@@ -50,5 +50,9 @@ class SchroederReverbAudioProcessor final : public juce::AudioProcessor
     SchroederReverb schroederReverb;
     juce::AudioParameterFloat* dryWetMix;
     juce::AudioParameterFloat* decayFactor;
+    juce::AudioParameterFloat* preDelay;
+
+    float lastPreDelay = 0.0f;
+
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(SchroederReverbAudioProcessor)
 };