SimdTypes_neon.h

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/*
  Neon version of SIMD types.
 */
 
#pragma once
 
#if _MSC_VER
#include <arm64_neon.h>
#define __finl __forceinline
#define __vecc __vectorcall
#else
#include <arm_neon.h>
#define __finl inline __attribute__((always_inline))
#define __vecc
#endif
 
#include <cmath>
 
namespace staffpad::audio::simd {
 
struct float_x4
{
  float32x4_t s;
 
  __finl float_x4()
  {
  }
 
  __finl float_x4(float val)
  {
    s = vdupq_n_f32(val);
  }
 
  __finl float_x4(const float32x4_t &val) : s(val)
  {
  }
 
  __finl float_x4(float v0, float v1, float v2, float v3)
  {
#if _MSC_VER // aggregate initializer won't work unless we have {.n128_f32 = ..} in c++20
    s.n128_f32[0] = v0;
    s.n128_f32[1] = v1;
    s.n128_f32[2] = v2;
    s.n128_f32[3] = v3;
#elif __clang__
    s = {v0, v1, v2, v3};
#else
    float f[4] = {v0, v1, v2, v3};
    s = vld1q_f32(f);
#endif
  }
 
#if __clang__
private:
  // this helper class allows writing to the single registers for clang
  // __mm128 is a built-in type -> we can't return a float& reference.
  // this is just syntax sugar and clang will remove it during builds.
  //
  // it allows to write
  // float_x4 a;
  // a[1] = 2.f;
  struct RegisterAccessWrapper
  {
    float32x4_t &val;
    int i;
 
    void operator=(float x)
    {
      val[i] = x;
    }
    operator float() noexcept
    {
      return val[i];
    }
  };
 
public:
  __finl RegisterAccessWrapper operator[](int n)
  {
    RegisterAccessWrapper raw = {s, n};
    return raw;
  }
 
  __finl const float operator[](int n) const
  {
    return s[n];
  }
#elif _MSC_VER
  // on msvc returning a ref to a sub-register is possible
  __finl float &operator[](int n)
  {
    return s.n128_f32[n];
  }
 
  __finl const float operator[](int n) const
  {
    return s.n128_f32[n];
  }
#endif
};
 
__finl float_x4 __vecc float_x4_from_float(float x)
{
  return vdupq_n_f32(x);
}
 
__finl float_x4 __vecc float_x4_load_aligned(const float *x)
{
  return vld1q_f32(x);
}
 
__finl void __vecc store_aligned(const float_x4 &a, float *x)
{
  vst1q_f32(x, a.s);
}
 
__finl float_x4 __vecc unzip1(const float_x4 &a, const float_x4 &b)
{
  return vuzp1q_f32(a.s, b.s);
}
 
__finl float_x4 __vecc unzip2(const float_x4 &a, const float_x4 &b)
{
  return vuzp2q_f32(a.s, b.s);
}
 
__finl float_x4 __vecc operator+(float_x4 a, float_x4 b)
{
  return vaddq_f32(a.s, b.s);
}
 
__finl float_x4 __vecc operator-(float_x4 a, float_x4 b)
{
  return vsubq_f32(a.s, b.s);
}
 
__finl float_x4 __vecc operator*(float_x4 a, float_x4 b)
{
  return vmulq_f32(a.s, b.s);
}
 
__finl float_x4 __vecc sqrt(const float_x4 &a)
{
  return vsqrtq_f32(a.s);
}
 
__finl float __vecc rint(float a)
{
  return std::rint(a);
}
 
__finl float_x4 __vecc rint(const float_x4 &a)
{
  return vrndnq_f32(a.s);
}
 
} // namespace staffpad::audio::simd