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
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