denormalprevention.h

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 Copyright (c) 2012-2016 Institut für Nachrichtentechnik, Universität Rostock
 Copyright (c) 2006-2012 Quality & Usability Lab
                         Deutsche Telekom Laboratories, TU Berlin
 
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// https://AudioProcessingFramework.github.io/
 
 
#ifndef APF_DENORMALPREVENTION_H
#define APF_DENORMALPREVENTION_H
 
#include <limits>  // for std::numeric_limits()
#include <cmath>  // for std::abs()
 
#ifdef __SSE__
#include <xmmintrin.h>  // for SSE intrinsics
#endif
#ifdef __SSE3__
#include <pmmintrin.h>  // for SSE3 intrinsics
#endif
 
namespace apf
{
 
namespace dp
{
 
template<typename T>
struct none
{
  void prevent_denormals(T&) {}
};
 
template<typename> struct dc;  // default case not implemented!
 
template<>
struct dc<float>
{
  static void prevent_denormals(float& val) { val += 1e-18f; }
};
 
template<>
struct dc<double>
{
  static void prevent_denormals(double& val) { val += 1e-30; }
};
 
template<typename> struct ac;  // default case not implemented!
 
template<>
struct ac<float>
{
  public:
    ac() : _anti_denorm(1e-18f) {}
 
    void prevent_denormals(float& val)
    {
      _anti_denorm = -_anti_denorm;
      val += _anti_denorm;
    }
 
  private:
    float _anti_denorm;
};
 
template<>
struct ac<double>
{
  public:
    ac() : _anti_denorm(1e-30) {}
 
    void prevent_denormals(double& val)
    {
      _anti_denorm = -_anti_denorm;
      val += _anti_denorm;
    }
 
  private:
    double _anti_denorm;
};
 
template<typename> struct quantization;  // default case not implemented!
 
template<>
struct quantization<float>
{
  static void prevent_denormals(float& val)
  {
    val += 1e-18f;
    val -= 1e-18f;
  }
};
 
template<>
struct quantization<double>
{
  static void prevent_denormals(double& val)
  {
    val += 1e-30;
    val -= 1e-30;
  }
};
 
template<typename T>
struct set_zero_1
{
  static void prevent_denormals(T& val)
  {
    if (std::abs(val) < std::numeric_limits<T>::min() && (val != 0)) val = 0;
  }
};
 
template<typename T>
struct set_zero_2
{
  static void prevent_denormals(T& val)
  {
    if ((val != 0) && std::abs(val) < std::numeric_limits<T>::min()) val = 0;
  }
};
 
template<typename T>
struct set_zero_3
{
  static void prevent_denormals(T& val)
  {
    if (std::abs(val) < std::numeric_limits<T>::min()) val = 0;
  }
};
 
#if 0
// add noise component; equally distributed spectrum
// NOTE: noise appears to be kind of deterministic
// - temporarily deactivated due to warnings
 
template<typename> struct NoisePrevention;
 
template<>
struct NoisePrevention<float>
{
  public:
    NoisePrevention() : _rand_state(1) {}
 
    void prevent_denormals(float& val)
    {
      _rand_state = _rand_state * 1234567UL + 890123UL;
      int mantissa = _rand_state & 0x807F0000; // Keep only most significant bits
      int flt_rnd = mantissa | 0x1E000000; // Set exponent
      val += *reinterpret_cast<const float*>(&flt_rnd);
    }
 
  private:
    unsigned int _rand_state;
};
#endif
 
#ifdef __SSE__
// The compiler must be set to generate SSE instructions automatically!
// In GCC, this is done with -mfpmath=sse (which is on by default on amd64)
 
inline void ftz_on()
{
  _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
}
 
inline void ftz_off()
{
  _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_OFF);
}
 
#ifdef __SSE3__
void daz_on()
{
  _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);
}
 
void daz_off()
{
  _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_OFF);
}
#endif
#endif
 
}  // namespace dp
 
}  // namespace apf
 
#endif