prepare
Prepares a JS5 buffer to be in a format read to be served to the clients, by splitting the payload up into chunks of 512 bytes, which each have a 0xFF terminator splitting them.
Parameters
archive
the archive id, written as a byte at the start
group
the group id, written as a short at the start
input
the input byte buffer from the cache, with version information stripped off
output
the output byte buffer into which to write the split-up JS5 buffers.