It turns out that MSB-first and LSB-first packing conventions both have advantages and disadvantages, and it’s much more useful to think of them as tools with different areas of application than it is to designate one as the “right way” and the other as the “wrong way”. - The ryg blog part 1 / 2 / 3

• Why is x86 little endian?

int32_t a = 0x01234567

see also

• htonl() vs __builtin_bswap32() - reverse byte order depending or not on localhost architecture
  • htonl == host to network long / htons => short / htoll => u64 ?
  • Is there a difference between ntohl() and htonl() ? => They do the exact same thing but have 2 different names. It doesn’t matter which one you call.
• GNU C has a uint64_t __builtin_bswap64 (uint64_t x)
• std::byteswap - since C++23