Unworkable is a single threaded and asynchronous BitTorrent implementation, written in portable ANSI C using libevent and mmap() for performance.

Unworkable is developed primarily under OpenBSD, however it has been written with portability in mind and should compile and run out of the box on at least:

• Various Linux flavours
• FreeBSD 6.2
• Mac OS X (both PPC and i386)
• Solaris 10
• Windows XP (cygwin)

I go out of my way to use slower, harsher platforms for development (e.g. old sparc64, g3 macppc, arm zaurus) to weed out endianness and pointer issues, and of course to get a feel for performance problems. This approach has led to quite reasonable CPU and memory requirements. Transferring at around 150KB/sec used 5% CPU and 1.4M memory on a 270Mhz UltraSparc II machine. Given that contemporary machines are roughly an order of magnitude faster than this, performance should be within acceptable bounds.