// Load PDFs of local cell: pdf_N = src[I(x, y, z, D3Q19_N)]; ...
// #define X(name, idx, idxinv, _x, _y, _z) JOIN(vpdf_,name) = VLDU(&src[I(x, y, z, idx)]);
// Load PDFs of local cell: pdf_N = src[I(x, y, z, D3Q19_N)]; ...
// #define X(name, idx, idxinv, _x, _y, _z) JOIN(vpdf_,name) = VLDU(&src[I(x, y, z, idx)]);