Messages in this thread | | | Date | Fri, 20 Dec 2013 19:51:31 +0800 | From | Chen Gang <> | Subject | Re: [PATCH] arch: metag: lib: add "umoddi3.S" file for __umoddi3() |
| |
On 12/20/2013 06:48 PM, James Hogan wrote: > On 20/12/13 10:20, Chen Gang wrote: >> Hmm... but do you know why we need some 64-bit functions which are >> implemented under "arch/metag/lib/*.S"? can we use <linux/math64.h> >> instead of them? (e.g 64-bit '/'). > > If you look at linux/math64.h you'll see it only implements division > operations. The other 64 bit operations like shift, compare, and > multiply are relatively cheap so are implemented as intrinsics instead. >
OK, thanks. tomorrow, I will send related patch: use 'div64_u64_rem' instead of umoddi3 ('%'). :-)
And I guess, in kernel wide, we need remove all 'umoddi3' and 'udivdi3'.
umoddi3 ('%'): frv, ia64, parisc, tile, xtensa udivdi3 ('/'): frv, ia64, parisc, tile, xtensa, sh, sparc. especially, sh and sparc only provide '/', do not provide '%'.
BTW: originally, I make a mistake -- treat 'udevsi3' as 'udevdi3'.
Thanks. -- Chen Gang
Open, share and attitude like air, water and life which God blessed
| |