bintree packing code

storeBinTree.cpp

static int storeBinTreesResult(BitStream &bs,const std::array<bintree_in,7> &bintree)
{
    // this least means that midpoint ( idx 0 ) depends on midpoint, but that's check with idx==0
    // then checking S - * - M - - - E   (idx 1)  depends on actual midpoint, and we check it
    // then checking S - - - M - * - E   (idx 2)  same as above
    // then checking S * - - M - - - E   (idx 3)  checking that we had SM/2 midpoint
    // then checking S - - * M - - - E   (idx 4)  checking that we had SM/2 midpoint
    // ...
    static const uint8_t dependency_indices[] = {0,0,0,1,1,2,2};
    static const uint8_t tree_depth_bits_mod[8] = { 1,2,2,3,3,3,3 };
    char num_bits;
    int val_sign;
    char base_bitcount;
    int res=0;
    std::array<bintree_in,7> tree_copy = bintree;
    base_bitcount = g_interpDataPrecision + 5;
    if(tree_copy[0].has_height && tree_copy[0].has_other)
    {
        // we have both values
        bs.StoreBits(1,1);

    }
    else
    {
        bs.StoreBits(1,tree_copy[0].has_height); // otherwise it is assumed that has_other is true
    }
    for (int idx = 0; idx < 7; ++idx )
    {
        if ( (idx && !tree_copy[dependency_indices[idx]].has_height) || tree_depth_bits_mod[idx] > g_interpolation_level )
            tree_copy[idx].has_height = 0; // mark dependency as missing
        else
        {
            if ( idx )
                bs.StoreBits(1, tree_copy[idx].has_height);
            if ( tree_copy[idx].has_height )
            {
                num_bits = base_bitcount - tree_depth_bits_mod[idx];
                res = 1;
                bs.StoreBits(1,tree_copy[idx].y<0);
                bs.StoreBits(num_bits,std::abs(tree_copy[idx].y));
            }
        }
    }
    for (int idx = 0; idx < 7; ++idx )
    {
        // check if the 'source' value for the one located at idx has xz values,
        if ( (idx && !tree_copy[dependency_indices[idx]].has_other) || tree_depth_bits_mod[idx] > g_interpolation_level )
            tree_copy[idx].has_other = false;
        else
        {
            if ( idx )
                bs.StoreBits(1, tree_copy[idx].has_other);
            if ( tree_copy[idx].has_other )
            {
                num_bits = base_bitcount - tree_depth_bits_mod[idx];
                res = 1;
                bs.StoreBits(1,tree_copy[idx].x<0);
                bs.StoreBits(num_bits,std::abs(tree_copy[idx].x));
                bs.StoreBits(1,tree_copy[idx].z<0);
                bs.StoreBits(num_bits,std::abs(tree_copy[idx].z));
            }
        }
    }
    return res;
}