Re: [boost] Proposed bit_struct submission to Boost

From: Kevin S. Van Horn (Kevin.VanHorn_at_[hidden])
Date: 2002-11-14 12:12:11

David Abrahams writes:

> Looks cool. I don't usually need such a thing, though. Could you give
> some examples of likely use cases?

The impetus for bit_struct was a discussion with a local business on possible
student library projects that would benefit the business.  This company writes
a lot of embedded software.  They are dealing with a network protocol that
allows them to pack any number of parameters into a message of exactly eight
bytes.  Note that byte order within multibyte integers is an issue I have not
addressed with bitstruct; if one wishes to send a bitstruct over the network,
then either the sender and receiver must have the same integer sizes and byte
orders, or you need an additional facility to put bytes into a standard order
(like the Unix htonl, htons, ntohl, and ntohs functions, but templatized.)

This kind of thing might also be useful in writing memory allocators, where
you want to tightly pack information into a small header for a block of
memory.  It might also be useful in implementing tagged data for
dynamically-typed languages.