DSP: Revamp DSP module

modules/juce_dsp/widgets/juce_Gain.h

@@ -0,0 +1,139 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE 6 technical preview.
+   Copyright (c) 2020 - Raw Material Software Limited
+
+   You may use this code under the terms of the GPL v3
+   (see www.gnu.org/licenses).
+
+   For this technical preview, this file is not subject to commercial licensing.
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+namespace dsp
+{
+
+/**
+    Applies a gain to audio samples as single samples or AudioBlocks.
+
+    @tags{DSP}
+*/
+template <typename FloatType>
+class Gain
+{
+public:
+    Gain() noexcept = default;
+
+    //==============================================================================
+    /** Applies a new gain as a linear value. */
+    void setGainLinear (FloatType newGain) noexcept             { gain.setTargetValue (newGain); }
+
+    /** Applies a new gain as a decibel value. */
+    void setGainDecibels (FloatType newGainDecibels) noexcept   { setGainLinear (Decibels::decibelsToGain<FloatType> (newGainDecibels)); }
+
+    /** Returns the current gain as a linear value. */
+    FloatType getGainLinear() const noexcept                    { return gain.getTargetValue(); }
+
+    /** Returns the current gain in decibels. */
+    FloatType getGainDecibels() const noexcept                  { return Decibels::gainToDecibels<FloatType> (getGainLinear()); }
+
+    /** Sets the length of the ramp used for smoothing gain changes. */
+    void setRampDurationSeconds (double newDurationSeconds) noexcept
+    {
+        if (rampDurationSeconds != newDurationSeconds)
+        {
+            rampDurationSeconds = newDurationSeconds;
+            reset();
+        }
+    }
+
+    /** Returns the ramp duration in seconds. */
+    double getRampDurationSeconds() const noexcept              { return rampDurationSeconds; }
+
+    /** Returns true if the current value is currently being interpolated. */
+    bool isSmoothing() const noexcept                           { return gain.isSmoothing(); }
+
+    //==============================================================================
+    /** Called before processing starts. */
+    void prepare (const ProcessSpec& spec) noexcept
+    {
+        sampleRate = spec.sampleRate;
+        reset();
+    }
+
+    /** Resets the internal state of the gain */
+    void reset() noexcept
+    {
+        if (sampleRate > 0)
+            gain.reset (sampleRate, rampDurationSeconds);
+    }
+
+    //==============================================================================
+    /** Returns the result of processing a single sample. */
+    template <typename SampleType>
+    SampleType JUCE_VECTOR_CALLTYPE processSample (SampleType s) noexcept
+    {
+        return s * gain.getNextValue();
+    }
+
+    /** Processes the input and output buffers supplied in the processing context. */
+    template <typename ProcessContext>
+    void process (const ProcessContext& context) noexcept
+    {
+        auto&& inBlock  = context.getInputBlock();
+        auto&& outBlock = context.getOutputBlock();
+
+        jassert (inBlock.getNumChannels() == outBlock.getNumChannels());
+        jassert (inBlock.getNumSamples() == outBlock.getNumSamples());
+
+        auto len         = inBlock.getNumSamples();
+        auto numChannels = inBlock.getNumChannels();
+
+        if (context.isBypassed)
+        {
+            gain.skip (static_cast<int> (len));
+
+            if (context.usesSeparateInputAndOutputBlocks())
+                outBlock.copyFrom (inBlock);
+
+            return;
+        }
+
+        if (numChannels == 1)
+        {
+            auto* src = inBlock.getChannelPointer (0);
+            auto* dst = outBlock.getChannelPointer (0);
+
+            for (size_t i = 0; i < len; ++i)
+                dst[i] = src[i] * gain.getNextValue();
+        }
+        else
+        {
+            auto* gains = static_cast<FloatType*> (alloca (sizeof (FloatType) * len));
+
+            for (size_t i = 0; i < len; ++i)
+                gains[i] = gain.getNextValue();
+
+            for (size_t chan = 0; chan < numChannels; ++chan)
+                FloatVectorOperations::multiply (outBlock.getChannelPointer (chan),
+                                                 inBlock.getChannelPointer (chan),
+                                                 gains, static_cast<int> (len));
+        }
+    }
+
+private:
+    //==============================================================================
+    SmoothedValue<FloatType> gain;
+    double sampleRate = 0, rampDurationSeconds = 0;
+};
+
+} // namespace dsp
+} // namespace juce