From 9f6158946987a5ce3f16da097d18f240a89db417 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Tue, 14 May 2019 15:43:08 -0700 Subject: lib/math: move int_pow() from pwm_bl.c for wider use The integer exponentiation is used in few places and might be used in the future by other call sites. Move it to wider use. Link: http://lkml.kernel.org/r/20190323172531.80025-2-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Cc: Daniel Thompson Cc: Lee Jones Cc: Ray Jui Cc: Thierry Reding Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/math/Makefile | 2 +- lib/math/int_pow.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 1 deletion(-) create mode 100644 lib/math/int_pow.c (limited to 'lib') diff --git a/lib/math/Makefile b/lib/math/Makefile index b75878420da6..583bbfebfc09 100644 --- a/lib/math/Makefile +++ b/lib/math/Makefile @@ -1,4 +1,4 @@ -obj-y += div64.o gcd.o lcm.o int_sqrt.o reciprocal_div.o +obj-y += div64.o gcd.o lcm.o int_pow.o int_sqrt.o reciprocal_div.o obj-$(CONFIG_CORDIC) += cordic.o obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o diff --git a/lib/math/int_pow.c b/lib/math/int_pow.c new file mode 100644 index 000000000000..622fc1ab3c74 --- /dev/null +++ b/lib/math/int_pow.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * An integer based power function + * + * Derived from drivers/video/backlight/pwm_bl.c + */ + +#include +#include +#include + +/** + * int_pow - computes the exponentiation of the given base and exponent + * @base: base which will be raised to the given power + * @exp: power to be raised to + * + * Computes: pow(base, exp), i.e. @base raised to the @exp power + */ +u64 int_pow(u64 base, unsigned int exp) +{ + u64 result = 1; + + while (exp) { + if (exp & 1) + result *= base; + exp >>= 1; + base *= base; + } + + return result; +} +EXPORT_SYMBOL_GPL(int_pow); -- cgit v1.2.3-59-g8ed1b