diff options
Diffstat (limited to 'lib/div64.c')
| -rw-r--r-- | lib/div64.c | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/lib/div64.c b/lib/div64.c index 5b491919177..4382ad77777 100644 --- a/lib/div64.c +++ b/lib/div64.c @@ -16,7 +16,8 @@ * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S. */ -#include <linux/module.h> +#include <linux/export.h> +#include <linux/kernel.h> #include <linux/math64.h> /* Not needed on 64bit architectures */ @@ -78,6 +79,46 @@ EXPORT_SYMBOL(div_s64_rem); #endif /** + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * @remainder: 64bit remainder + * + * This implementation is a comparable to algorithm used by div64_u64. + * But this operation, which includes math for calculating the remainder, + * is kept distinct to avoid slowing down the div64_u64 operation on 32bit + * systems. + */ +#ifndef div64_u64_rem +u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) +{ + u32 high = divisor >> 32; + u64 quot; + + if (high == 0) { + u32 rem32; + quot = div_u64_rem(dividend, divisor, &rem32); + *remainder = rem32; + } else { + int n = 1 + fls(high); + quot = div_u64(dividend >> n, divisor >> n); + + if (quot != 0) + quot--; + + *remainder = dividend - quot * divisor; + if (*remainder >= divisor) { + quot++; + *remainder -= divisor; + } + } + + return quot; +} +EXPORT_SYMBOL(div64_u64_rem); +#endif + +/** * div64_u64 - unsigned 64bit divide with 64bit divisor * @dividend: 64bit dividend * @divisor: 64bit divisor @@ -86,7 +127,7 @@ EXPORT_SYMBOL(div_s64_rem); * by the book 'Hacker's Delight'. The original source and full proof * can be found here and is available for use without restriction. * - * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c' + * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt' */ #ifndef div64_u64 u64 div64_u64(u64 dividend, u64 divisor) |