libigl_Martin/include/igl/Singular_Value_Decomposition_Preamble.hpp

//#####################################################################
// Copyright (c) 2010-2011, Eftychios Sifakis.
//
// Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
//   * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or
//     other materials provided with the distribution.
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#ifdef PRINT_DEBUGGING_OUTPUT
#include <iomanip>
#include <iostream>
#endif

#ifdef USE_SCALAR_IMPLEMENTATION
#define ENABLE_SCALAR_IMPLEMENTATION(X) X
#else
#define ENABLE_SCALAR_IMPLEMENTATION(X)
#endif

#ifdef USE_SSE_IMPLEMENTATION
#define ENABLE_SSE_IMPLEMENTATION(X) X
#else
#define ENABLE_SSE_IMPLEMENTATION(X)
#endif

#ifdef USE_AVX_IMPLEMENTATION
#include <immintrin.h>
#define ENABLE_AVX_IMPLEMENTATION(X) X
#else
// Stefan: removed include. Why does it import MMX instructions, shouldn't this be under the #ifdef USE_SSE_IMPLEMENTATION above?
//#include <xmmintrin.h>
#define ENABLE_AVX_IMPLEMENTATION(X)
#endif

#ifdef USE_SCALAR_IMPLEMENTATION
// Alec: Why is this using sse intrinsics if it's supposed to be the scalar
// implementation?
#ifdef __SSE__
#include <mmintrin.h>
// Changed to inline
inline float rsqrt(const float f)
{
    float buf[4];
    buf[0]=f;
    __m128 v=_mm_loadu_ps(buf);
    v=_mm_rsqrt_ss(v);
    _mm_storeu_ps(buf,v);
    return buf[0];
}
#else
#include <cmath>
inline float rsqrt(const float f)
{
  return 1./sqrtf(f);
}
#endif
#endif