On Fri, Nov 12, 2010 at 06:35:32PM +0000, Eduardo Horvath wrote: > Take, for example, the simple act of byte swapping network data. x86 has > a bswap instruction. SPARC and PowerPC architectures have a multiplexer > on the load/store. (Don't know about MIPS, don't remember about ARM.) In > order to swap a 64-bit value in registers you need to issue a series of > shift, mask, and or instrutions, usually about 8 of them, most of which > are depenent (cannot be issued in parallel on a superscalar machine). > The macro NetBSD uses here is bswap64(). This maps very well to the x86 > instruction, but is really not usable for any machine that does the > swapping in the load/store path. Instead we could use something like > load_be64()/load_le64()/store_be64()/store_le64() which could be mapped to > a reverse-endian load/store instruction on architetures that support it > and bswap on x86.
If you look at sys/endian.h, that is exactly the kind of abstraction the API makes easy to use. Just provide the proper inline functions for your platform. Joerg