Hi Bill, On Fri, 30 Nov 2007 07:04:10 -0600, Bill Gatliff wrote: > Jean Delvare wrote: > > !!(value & (1 << offset)) > > is more efficiently written > > (value >> offset) & 1 > > ... but not more efficiently implemented. > > Your version requires code to do the shift on live data at runtime. > David's version lets the compiler create the mask once, at compile-time.
I don't understand. How could the compiler create the mask at compile-time when "offset" is only known at runtime? Anyway, I just checked and gcc (4.1.2 on x86_86) generates the same code for both expressions, so there's not much to argue about. David, feel free to ignore my comment if you prefer your implementation :) -- Jean Delvare - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/