faster_corner_utilities.h

#ifndef CVD_INTERNAL_INC_FAST_CORNER_UTILITIES_H
#define CVD_INTERNAL_INC_FAST_CORNER_UTILITIES_H

#include <emmintrin.h>

namespace CVD
{

struct Less
{
    template <class T1, class T2>
    static bool eval(const T1 a, const T2 b)
    {
        return a < b;
    }
    static int prep_t(int pixel_val, int barrier)
    {
        return pixel_val - barrier;
    }
};
struct Greater
{
    template <class T1, class T2>
    static bool eval(const T1 a, const T2 b)
    {
        return a > b;
    }
    static int prep_t(int pixel_val, int barrier)
    {
        return pixel_val + barrier;
    }
};

#define CHECK_BARRIER(lo, hi, other, flags)                                    \
    {                                                                          \
        __m128i diff = _mm_subs_epu8(lo, other);                               \
        __m128i diff2 = _mm_subs_epu8(other, hi);                              \
        __m128i z = _mm_setzero_si128();                                       \
        diff = _mm_cmpeq_epi8(diff, z);                                        \
        diff2 = _mm_cmpeq_epi8(diff2, z);                                      \
        flags = ~(_mm_movemask_epi8(diff) | (_mm_movemask_epi8(diff2) << 16)); \
    }

template <bool Aligned>
inline __m128i load_si128(const void* addr)
{
    return _mm_loadu_si128((const __m128i*)addr);
}
template <>
inline __m128i load_si128<true>(const void* addr) { return _mm_load_si128((const __m128i*)addr); }

}
#endif