- refactored

- BufferMulti numChannels is template parameter

common/mix.hpp

@@ -0,0 +1,94 @@
+#ifndef MIX_HPP
+#define MIX_HPP
+
+#include <cmath>
+
+// Use like `Householder<double, 8>::inPlace(data)` - size must be ≥ 1
+template<typename Sample, int size>
+class Householder
+{
+	static constexpr Sample multiplier{-2.0/size};
+	
+	public:
+	static void inPlace(Sample *arr)
+	{
+		double sum = 0;
+		for (int i = 0; i < size; ++i)
+		{
+			sum += arr[i];
+		}
+
+		sum *= multiplier;
+		
+		for (int i = 0; i < size; ++i)
+		{
+			arr[i] += sum;
+		}
+	};
+};
+
+// Use like `Hadamard<double, 8>::inPlace(data)` - size must be a power of 2
+template<typename Sample, int size>
+class Hadamard
+{
+	public: 
+	static inline void recursiveUnscaled(Sample * data)
+	{
+		if (size <= 1)
+		{
+			return;
+		}
+		constexpr int hSize = size/2;
+
+		// Two (unscaled) Hadamards of half the size
+		Hadamard<Sample, hSize>::recursiveUnscaled(data);
+		Hadamard<Sample, hSize>::recursiveUnscaled(data + hSize);
+
+		// Combine the two halves using sum/difference
+		for (int i = 0; i < hSize; ++i)
+		{
+			double a = data[i];
+			double b = data[i + hSize];
+			data[i] = (a + b);
+			data[i + hSize] = (a - b);
+		}
+	}
+
+	static inline void inPlace(Sample * data)
+	{
+		recursiveUnscaled(data);
+		
+		Sample scalingFactor = std::sqrt(1.0/size);
+		for (int c = 0; c < size; ++c)
+		{
+			data[c] *= scalingFactor;
+		}
+	}
+};
+
+template<typename T, uint numCh>
+class Shuffle
+{
+	public: 
+	static inline void outOfPlace(T *in, T *out, const int *shuffle_spec)
+	{
+		for (int c=0; c < numCh; c++)
+		{
+			T sign = 1;
+			int s = shuffle_spec[c];
+			if (s < 0)
+			{
+				sign = -1;
+				s *= -1;
+			}
+			if (s >= numCh)
+			{
+				s = 0;
+			}
+
+			out[s] = sign * in[c];
+		}
+	};
+};
+
+#endif