Packing a map tile address into a cozy little 64-bit integer

PackedTileAddress.cpp

#include <cassert>
#include <cstdio>
#include <cstdint>

struct TileAddress {
    int x = 0;
    int y = 0;
    int z = 0;
    int s = 0;
};

uint64_t AddressToId(TileAddress address) {
    assert(address.x < (1 << 24));
    assert(address.y < (1 << 24));
    assert(address.z < (1 << 8));
    assert(address.s < (1 << 8));
    uint64_t out = address.s;
    out = (out << 8) | address.z;
    out = (out << 24) | address.y;
    out = (out << 24) | address.x;
    return out;
}

TileAddress IdToAddress(uint64_t id) {
    TileAddress out;
    out.x = (id) & 0xFFFFFF;
    out.y = (id >> 24) & 0xFFFFFF;
    out.z = (id >> 48) & 0xFF;
    out.s = (id >> 56);
    return out;
}

int main() {
    TileAddress t { 2, 3, 4, 5 };
    printf("sizeof TileAddress: %lu\n", sizeof(t));
    printf("TileAddress: x = %d, y = %d, z = %d\n", t.x, t.y, t.z);
    auto id = AddressToId(t);
    printf("AddressToId: %#llx\n", id);
    auto r = IdToAddress(id);
    printf("Round trip: x = %d, y = %d, z = %d, s = %d\n", r.x, r.y, r.z, r.s);

    TileAddress lower { 6, 4, 3, 3 };
    TileAddress upper { 1, 2, 5, 5 };
    auto lowerId = AddressToId(lower);
    auto upperId = AddressToId(upper);
    printf("lowerId = %#llx, upperId = %#llx\n", lowerId, upperId);
    assert(lowerId < upperId);
}