| Message ID | 20171220093315.25311-1-cmo@melexis.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 2017-12-20 at 10:33 +0100, Crt Mori wrote: > There is no option to perform 64bit integer sqrt on 32bit platform. > Added stronger typed int_sqrt64 enables the 64bit calculations to > be performed on 32bit platforms. Although int_sqrt() is a rough > approximation, the same algorithm is used in int_sqrt64() as good > enough on 32bit platform. [] > diff --git a/include/linux/kernel.h b/include/linux/kernel.h [] > @@ -459,6 +459,7 @@ extern int kernel_text_address(unsigned long addr); > extern int func_ptr_is_kernel_text(void *ptr); > > unsigned long int_sqrt(unsigned long); > +u32 int_sqrt64(u64 x); #ifdef BITS_PER_LONG == 64 static inline u32 int_sqrt64(u64 x) { re turn (u32)int_sqrt(x); } #else u32 int_sqrt64(u64 x); #endif [] > +#if BITS_PER_LONG < 64 > +/** > + * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input > + * is expected. > + * @x: 64bit integer of which to calculate the sqrt > + */ > +u32 int_sqrt64(u64 x) > +{ > + u64 b, m, y = 0; > + > + if (x <= 1) > + return x; > + > + m = 1ULL << (fls64(x) & ~1ULL); > + while (m != 0) { > + b = y + m; > + y >>= 1; > + > + if (x >= b) { > + x -= b; > + y += m; > + } > + m >>= 2; > + } > + > + return y; > +} > +EXPORT_SYMBOL(int_sqrt64); > +#else > +u32 int_sqrt64(u64 x) > +{ > + return int_sqrt(x); > +} > +EXPORT_SYMBOL(int_sqrt64); > +#endif This doesn't need to be EXPORT_SYMBOL for the BITS_PER_LONG == 64 case -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 20 December 2017 at 10:56, Joe Perches <joe@perches.com> wrote: > On Wed, 2017-12-20 at 10:33 +0100, Crt Mori wrote: >> There is no option to perform 64bit integer sqrt on 32bit platform. >> Added stronger typed int_sqrt64 enables the 64bit calculations to >> be performed on 32bit platforms. Although int_sqrt() is a rough >> approximation, the same algorithm is used in int_sqrt64() as good >> enough on 32bit platform. > [] >> diff --git a/include/linux/kernel.h b/include/linux/kernel.h > [] >> @@ -459,6 +459,7 @@ extern int kernel_text_address(unsigned long addr); >> extern int func_ptr_is_kernel_text(void *ptr); >> >> unsigned long int_sqrt(unsigned long); >> +u32 int_sqrt64(u64 x); > > #ifdef BITS_PER_LONG == 64 > static inline u32 int_sqrt64(u64 x) > { > re > turn (u32)int_sqrt(x); > } > #else > u32 int_sqrt64(u64 x); > #endif > > [] > OK, fixing it in v10. >> +#if BITS_PER_LONG < 64 >> +/** >> + * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input >> + * is expected. >> + * @x: 64bit integer of which to calculate the sqrt >> + */ >> +u32 int_sqrt64(u64 x) >> +{ >> + u64 b, m, y = 0; >> + >> + if (x <= 1) >> + return x; >> + >> + m = 1ULL << (fls64(x) & ~1ULL); >> + while (m != 0) { >> + b = y + m; >> + y >>= 1; >> + >> + if (x >= b) { >> + x -= b; >> + y += m; >> + } >> + m >>= 2; >> + } >> + >> + return y; >> +} >> +EXPORT_SYMBOL(int_sqrt64); >> +#else >> +u32 int_sqrt64(u64 x) >> +{ >> + return int_sqrt(x); >> +} >> +EXPORT_SYMBOL(int_sqrt64); >> +#endif > > This doesn't need to be EXPORT_SYMBOL for the > BITS_PER_LONG == 64 case > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 0ad4c3044cf9..5c6949e9e309 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -459,6 +459,7 @@ extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); unsigned long int_sqrt(unsigned long); +u32 int_sqrt64(u64 x); 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 1ef4cc344977..30acab761dc1 100644 --- a/lib/int_sqrt.c +++ b/lib/int_sqrt.c @@ -7,6 +7,7 @@ #include <linux/kernel.h> #include <linux/export.h> +#include <linux/bitops.h> /** * int_sqrt - rough approximation to sqrt @@ -36,3 +37,39 @@ unsigned long int_sqrt(unsigned long x) return y; } EXPORT_SYMBOL(int_sqrt); + +#if BITS_PER_LONG < 64 +/** + * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input + * is expected. + * @x: 64bit integer of which to calculate the sqrt + */ +u32 int_sqrt64(u64 x) +{ + u64 b, m, y = 0; + + if (x <= 1) + return x; + + m = 1ULL << (fls64(x) & ~1ULL); + while (m != 0) { + b = y + m; + y >>= 1; + + if (x >= b) { + x -= b; + y += m; + } + m >>= 2; + } + + return y; +} +EXPORT_SYMBOL(int_sqrt64); +#else +u32 int_sqrt64(u64 x) +{ + return int_sqrt(x); +} +EXPORT_SYMBOL(int_sqrt64); +#endif
There is no option to perform 64bit integer sqrt on 32bit platform. Added stronger typed int_sqrt64 enables the 64bit calculations to be performed on 32bit platforms. Although int_sqrt() is a rough approximation, the same algorithm is used in int_sqrt64() as good enough on 32bit platform. Signed-off-by: Crt Mori <cmo@melexis.com> --- include/linux/kernel.h | 1 + lib/int_sqrt.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+)