On 07/12/16 09:42, Kalle Valo wrote: > Sebastian Frias <s...@laposte.net> writes: > >> Introduce GENVALUE(msb, lsb, value) macro to ease dealing with >> continuous bitfields, just as BIT(x) does for single bits. >> >> GENVALUE_ULL(msb, lsb, value) macro is also added. >> >> This is useful mostly for creating values to be packed together >> via OR operations, ex: >> >> u32 val = 0x11110000; >> val |= GENVALUE(19, 12, 0x5a); >> >> now 'val = 0x1115a000' >> >> >> Signed-off-by: Sebastian Frias <s...@laposte.net> >> Link: https://marc.info/?l=linux-kernel&m=148094498711000&w=2 >> --- >> >> Change in v2: >> - rename the macro to GENVALUE as proposed by Linus >> - longer comment attempts to show use case for the macro as >> proposed by Borislav >> >> Change in v3: >> - use BUILD_BUG_ON_ZERO() to break if some input parameters >> (essentially 'lsb' but also 'msb') are not constants as >> proposed by Linus. >> Indeed, 'lsb' is used twice so it cannot have side-effects; >> 'msb' is subjected to same constraints for consistency. > > (I missed there was v3 already, but I'll repeat what I said in v1.) > > Please check FIELD_PREP() from include/linux/bitfield.h, doesn't it > already do the same?
Indeed, it appears to do the same :-) Any reason why "include/linux/bitfield.h" is not included by default in bitops.h?
