shairport-sync/FFTConvolver/Utilities.h

// ==================================================================================
// Copyright (c) 2017 HiFi-LoFi
//
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// of this software and associated documentation files (the "Software"), to deal
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// The above copyright notice and this permission notice shall be included in
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// ==================================================================================

#ifndef _FFTCONVOLVER_UTILITIES_H
#define _FFTCONVOLVER_UTILITIES_H

#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstring>
#include <new>

namespace fftconvolver {

#if defined(__SSE__) || (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
#if !defined(FFTCONVOLVER_USE_SSE) && !defined(FFTCONVOLVER_DONT_USE_SSE)
#define FFTCONVOLVER_USE_SSE
#endif
#endif

#if defined(FFTCONVOLVER_USE_SSE)
#include <xmmintrin.h>
#endif

#if defined(__GNUC__)
#define FFTCONVOLVER_RESTRICT __restrict__
#else
#define FFTCONVOLVER_RESTRICT
#endif

/**
 * @brief Returns whether SSE optimization for the convolver is enabled
 * @return true: Enabled - false: Disabled
 */
bool SSEEnabled();

/**
 * @class Buffer
 * @brief Simple buffer implementation (uses 16-byte alignment if SSE optimization is enabled)
 */
template <typename T> class Buffer {
public:
  explicit Buffer(size_t initialSize = 0) : _data(0), _size(0) { resize(initialSize); }

  virtual ~Buffer() { clear(); }

  void clear() {
    deallocate(_data);
    _data = 0;
    _size = 0;
  }

  void resize(size_t size) {
    if (_size != size) {
      clear();

      if (size > 0) {
        assert(!_data && _size == 0);
        _data = allocate(size);
        _size = size;
      }
    }
    setZero();
  }

  size_t size() const { return _size; }

  void setZero() { ::memset(_data, 0, _size * sizeof(T)); }

  void copyFrom(const Buffer<T> &other) {
    assert(_size == other._size);
    if (this != &other) {
      ::memcpy(_data, other._data, _size * sizeof(T));
    }
  }

  T &operator[](size_t index) {
    assert(_data && index < _size);
    return _data[index];
  }

  const T &operator[](size_t index) const {
    assert(_data && index < _size);
    return _data[index];
  }

  operator bool() const { return (_data != 0 && _size > 0); }

  T *data() { return _data; }

  const T *data() const { return _data; }

  static void Swap(Buffer<T> &a, Buffer<T> &b) {
    std::swap(a._data, b._data);
    std::swap(a._size, b._size);
  }

private:
  T *allocate(size_t size) {
#if defined(FFTCONVOLVER_USE_SSE)
    return static_cast<T *>(_mm_malloc(size * sizeof(T), 16));
#else
    return new T[size];
#endif
  }

  void deallocate(T *ptr) {
#if defined(FFTCONVOLVER_USE_SSE)
    _mm_free(ptr);
#else
    delete[] ptr;
#endif
  }

  T *_data;
  size_t _size;

  // Prevent uncontrolled usage
  Buffer(const Buffer &);
  Buffer &operator=(const Buffer &);
};

/**
 * @brief Type of one sample
 */
typedef float Sample;

/**
 * @brief Buffer for samples
 */
typedef Buffer<Sample> SampleBuffer;

/**
 * @class SplitComplex
 * @brief Buffer for split-complex representation of FFT results
 *
 * The split-complex representation stores the real and imaginary parts
 * of FFT results in two different memory buffers which is useful e.g. for
 * SIMD optimizations.
 */
class SplitComplex {
public:
  explicit SplitComplex(size_t initialSize = 0) : _size(0), _re(), _im() { resize(initialSize); }

  ~SplitComplex() { clear(); }

  void clear() {
    _re.clear();
    _im.clear();
    _size = 0;
  }

  void resize(size_t newSize) {
    _re.resize(newSize);
    _im.resize(newSize);
    _size = newSize;
  }

  void setZero() {
    _re.setZero();
    _im.setZero();
  }

  void copyFrom(const SplitComplex &other) {
    _re.copyFrom(other._re);
    _im.copyFrom(other._im);
  }

  Sample *re() { return _re.data(); }

  const Sample *re() const { return _re.data(); }

  Sample *im() { return _im.data(); }

  const Sample *im() const { return _im.data(); }

  size_t size() const { return _size; }

private:
  size_t _size;
  SampleBuffer _re;
  SampleBuffer _im;

  // Prevent uncontrolled usage
  SplitComplex(const SplitComplex &);
  SplitComplex &operator=(const SplitComplex &);
};

/**
 * @brief Returns the next power of 2 of a given number
 * @param val The number
 * @return The next power of 2
 */
template <typename T> T NextPowerOf2(const T &val) {
  T nextPowerOf2 = 1;
  while (nextPowerOf2 < val) {
    nextPowerOf2 *= 2;
  }
  return nextPowerOf2;
}

/**
 * @brief Sums two given sample arrays
 * @param result The result array
 * @param a The 1st array
 * @param b The 2nd array
 * @param len The length of the arrays
 */
void Sum(Sample *FFTCONVOLVER_RESTRICT result, const Sample *FFTCONVOLVER_RESTRICT a,
         const Sample *FFTCONVOLVER_RESTRICT b, size_t len);

/**
 * @brief Copies a source array into a destination buffer and pads the destination buffer with zeros
 * @param dest The destination buffer
 * @param src The source array
 * @param srcSize The size of the source array
 */
template <typename T> void CopyAndPad(Buffer<T> &dest, const T *src, size_t srcSize) {
  assert(dest.size() >= srcSize);
  ::memcpy(dest.data(), src, srcSize * sizeof(T));
  ::memset(dest.data() + srcSize, 0, (dest.size() - srcSize) * sizeof(T));
}

/**
 * @brief Adds the complex product of two split-complex buffers to a result buffer
 * @param result The result buffer
 * @param a The 1st factor of the complex product
 * @param b The 2nd factor of the complex product
 */
void ComplexMultiplyAccumulate(SplitComplex &result, const SplitComplex &a, const SplitComplex &b);

/**
 * @brief Adds the complex product of two split-complex arrays to a result array
 * @param re The real part of the result buffer
 * @param im The imaginary part of the result buffer
 * @param reA The real part of the 1st factor of the complex product
 * @param imA The imaginary part of the 1st factor of the complex product
 * @param reB The real part of the 2nd factor of the complex product
 * @param imB The imaginary part of the 2nd factor of the complex product
 */
void ComplexMultiplyAccumulate(Sample *FFTCONVOLVER_RESTRICT re, Sample *FFTCONVOLVER_RESTRICT im,
                               const Sample *FFTCONVOLVER_RESTRICT reA,
                               const Sample *FFTCONVOLVER_RESTRICT imA,
                               const Sample *FFTCONVOLVER_RESTRICT reB,
                               const Sample *FFTCONVOLVER_RESTRICT imB, const size_t len);

} // End of namespace fftconvolver

#endif // Header guard