Jim Bryant <kc5vdj.free...@gmail.com> wrote: > well, i can't speak for K&R 1978, as i can't currently find my copy, > but, for a quick brush up, you might want to read pages 80 and 81 > from K&R 2nd Ed. 1988. > > your idea that the preprocessor will evaluate > > #define thirtytwok (1<<15) > > into 0x8000 > > at compile time is totally incorrect, and in fact wouldn't be in > compliance with standards. i have iso and fips handy, care for > quotes?
Who said anything about the preprocessor? The preprocessor is supposed to only do text substitutions, so you're right that _it_ doesn't (or at least, shouldn't) replace (1<<15) with 0x8000. The *compiler* does it. Look up "constant expressions". If you find a C compiler that generates a load and shift to evaluate (1<<15) at runtime, your next move should be to file a bug report with its maintainer -- unless you're dealing with a processor which can do the load and shift in less time or space than a direct load of 0x8000. And BTW, please don't top-post. _______________________________________________ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "freebsd-usb-unsubscr...@freebsd.org"
