VisionFive2 Linux kernel

9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  1) // SPDX-License-Identifier: GPL-2.0
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  2) /*
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  3)  * An integer based power function
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  4)  *
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  5)  * Derived from drivers/video/backlight/pwm_bl.c
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  6)  */
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  7) 
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700  8) #include <linux/export.h>
aa6159ab99a9a (Andy Shevchenko 2020-12-15 20:42:48 -0800  9) #include <linux/math.h>
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 10) #include <linux/types.h>
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 11) 
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 12) /**
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 13)  * int_pow - computes the exponentiation of the given base and exponent
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 14)  * @base: base which will be raised to the given power
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 15)  * @exp: power to be raised to
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 16)  *
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 17)  * Computes: pow(base, exp), i.e. @base raised to the @exp power
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 18)  */
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 19) u64 int_pow(u64 base, unsigned int exp)
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 20) {
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 21) 	u64 result = 1;
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 22) 
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 23) 	while (exp) {
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 24) 		if (exp & 1)
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 25) 			result *= base;
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 26) 		exp >>= 1;
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 27) 		base *= base;
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 28) 	}
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 29) 
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 30) 	return result;
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 31) }
9f6158946987a (Andy Shevchenko 2019-05-14 15:43:08 -0700 32) EXPORT_SYMBOL_GPL(int_pow);