median.hxx

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#ifndef _UTILS_MEDIAN_HXX_
#define _UTILS_MEDIAN_HXX_
 
inline void __attribute__((__always_inline__, optimize("O3")))
comp_swap(unsigned &a, unsigned &b)
{
    if (a > b)
    {
        unsigned tmp = a;
        a = b;
        b = tmp;
    }
}
 
inline unsigned __attribute__((__always_inline__, optimize("O3")))
median_5(unsigned a, unsigned b, unsigned c, unsigned d, unsigned e)
{
    comp_swap(a, c);
    comp_swap(b, d);
    comp_swap(a, b);
    comp_swap(c, d);
    // Now: a is the smallest of [a,b,c,d]
    // d is the greatest of [a,b,c,d]; neither of these can be the median.
    comp_swap(b, c);
    // Now: [a,b,c,d] are sorted
    if (e > c) {
        return c;
    }
    if (e < b) {
        return b;
    }
    return e;
}
 
#endif // _UTILS_MEDIAN_HXX_