On 11/5/2015 2:56 PM, Andy Shevchenko wrote:
On Thu, Nov 5, 2015 at 9:31 PM, Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
On Thu, Nov 5, 2015 at 8:32 PM, Sinan Kaya <okaya@xxxxxxxxxxxxxx> wrote:
On 11/5/2015 1:07 PM, Andy Shevchenko wrote:
Let's try again.
static inline u64 mult_frac64(u64 x, u32 numer, u32 denom) {
u64 rem = x % denom;
u64 quot = do_div(x, denom);
u64 mul = rem * numer;
return (quot * numer) + do_div(mul, denom);
}
First of all why not to put this to generic header? We have math64.h
and kernel.h.
Might be a good idea (needs to check current users) to move mult_frac
to math64.h.
Then, x % y is already a problem. After all, you seems messed quot and
remainder.
What about something like
#if BITS_PER_LONG == 64
#define mult_frac64(x,n,d) mult_frac(x,n,d)
#else
static inline u64 mult_frac64(u64 x, u32 numer, u32 denom) {
u64 r1 = do_div(x, denom);
u64 r2 = r1 * numer;
do_div(r2, denom);
return (x * numer) + r2;
}
I'll use this instead. This is cleaner, scalable and functionally
correct to the original code. I'll post a patch with this soon.
#endif
?
One more look to the users of MULDIV.
They all seems 32 bit for x.
It means you don't need two do_div()s at all.
Just do something like:
u64 d = x * numer;
do_div(d, denom);
return d;
--
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
Linux Foundation Collaborative Project
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