gbox_get_sortable_hash()

uint64_t gbox_get_sortable_hash

(

const GBOX *

g

)

Return a sortable key based on the center point of the GBOX.

Definition at line 259 of file g_serialized.c.

References cart2geog(), floatuint::f, GBOX::flags, FLAGS_GET_GEODETIC, GEOGRAPHIC_POINT::lat, GEOGRAPHIC_POINT::lon, normalize(), floatuint::u, uint32_interleave_2(), POINT3D::x, GBOX::xmax, GBOX::xmin, POINT3D::y, GBOX::ymax, GBOX::ymin, POINT3D::z, GBOX::zmax, and GBOX::zmin.

Referenced by gserialized_cmp().

{
        union floatuint x, y;

        /*
        * Since in theory the bitwise representation of an IEEE
        * float is sortable (exponents come before mantissa, etc)
        * we just copy the bits directly into an int and then
        * interleave those ints.
        */
        if ( FLAGS_GET_GEODETIC(g->flags) )
        {
                GEOGRAPHIC_POINT gpt;
                POINT3D p;
                p.x = (g->xmax + g->xmin) / 2.0;
                p.y = (g->ymax + g->ymin) / 2.0;
                p.z = (g->zmax + g->zmin) / 2.0;
                normalize(&p);
                cart2geog(&p, &gpt);
                x.f = gpt.lon;
                y.f = gpt.lat;
        }
        else
        {
                /*
                * Here we'd like to get two ordinates from 4 in the box.
                * Since it's just a sortable bit representation we can omit division from (A+B)/2.
                * All it should do is subtract 1 from exponent anyways.
                */
                x.f = g->xmax + g->xmin;
                y.f = g->ymax + g->ymin;
        }
        return uint32_interleave_2(x.u, y.u);
}

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