in lib/h3core.js [411:418]
function storeH3Index(h3Index, cAddress, offset) {
// HEAPU32 is a typed array projection on the index space
// as unsigned 32-bit integers. This means the index needs
// to be divided by SZ_INT (4) to access correctly. Also,
// the H3 index is 64 bits, so we skip by twos as we're writing
// to 32-bit integers in the proper order.
C.HEAPU32.set(h3IndexToSplitLong(h3Index), cAddress / SZ_INT + 2 * offset);
}