Hello,
> > maybe the code could be #MACRO()'d to avoid duplication
>
> Do you mean to define int64_sqrt() directly as int_sqrt() on a 64 bit
> platform where sizeof(long) == sizeof(long long)?
something along the lines of
#define INT_SQRT(name, type) \
type name(type x) \
type m, y = 0, b; \
...
INT_SQRT(int_sqrt, unsigned long);
INT_SQRT(int64_sqrt, unsigned long long);
not sure if it is worth it
regards, p.
> ________________________________________
> From: Peter Meerwald [pmeerw@xxxxxxxxxx]
> Sent: Monday, June 23, 2014 5:52 PM
> To: Barry Song
> Cc: dmitry.torokhov@xxxxxxxxx; dtor@xxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; linux-input@xxxxxxxxxxxxxxx; DL-SHA-WorkGroupLinux; Yibo Cai; Barry Song
> Subject: Re: [PATCH 1/2] lib: int_sqrt: add int64_sqrt routine
>
> > Get square root of a 64-bit digit on 32bit platforms. CSR SiRFSoC
> > touchscreen driver needs it.
>
> maybe the code could be #MACRO()'d to avoid duplication
>
> see comment below
>
> > diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> > index 4c52907..6e63081 100644
> > --- a/include/linux/kernel.h
> > +++ b/include/linux/kernel.h
> > @@ -418,6 +418,7 @@ struct pid;
> > extern struct pid *session_of_pgrp(struct pid *pgrp);
> >
> > unsigned long int_sqrt(unsigned long);
> > +unsigned long long int64_sqrt(unsigned long long);
> >
> > extern void bust_spinlocks(int yes);
> > extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */
> > diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
> > index 1ef4cc3..2aa9fcc 100644
> > --- a/lib/int_sqrt.c
> > +++ b/lib/int_sqrt.c
> > @@ -36,3 +36,30 @@ unsigned long int_sqrt(unsigned long x)
> > return y;
> > }
> > EXPORT_SYMBOL(int_sqrt);
> > +
> > +/*
> > + * Square root of a 64-bit digit.
> > + * Same as int_sqrt on 64-bit platforms where "long" equals "long long"
> > + */
> > +unsigned long long int64_sqrt(unsigned long long x)
> > +{
> > + unsigned long long m = 0, y = 0, b = 0;
>
> initialization for b, m not needed
>
> the original int_sqrt() code correctly skips initialization
>
> > +
> > + if (x <= 1)
> > + return x;
> > +
> > + m = 1ULL << (BITS_PER_LONG_LONG - 2);
> > + while (m != 0) {
> > + b = y + m;
> > + y >>= 1;
> > +
> > + if (x >= b) {
> > + x -= b;
> > + y += m;
> > + }
> > + m >>= 2;
> > + }
> > +
> > + return y;
> > +}
> > +EXPORT_SYMBOL(int64_sqrt);
> >
>
> --
>
> Peter Meerwald
> +43-664-2444418 (mobile)
>
>
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--
Peter Meerwald
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