diff options
| -rw-r--r-- | include/linux/math64.h | 13 | ||||
| -rw-r--r-- | lib/div64.c | 40 |
2 files changed, 53 insertions, 0 deletions
diff --git a/include/linux/math64.h b/include/linux/math64.h index 2913b86eb12a..69ed5f5e9f6e 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -31,6 +31,15 @@ static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) } /** + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder + */ +static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) +{ + *remainder = dividend % divisor; + return dividend / divisor; +} + +/** * div64_u64 - unsigned 64bit divide with 64bit divisor */ static inline u64 div64_u64(u64 dividend, u64 divisor) @@ -63,6 +72,10 @@ static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder); #endif +#ifndef div64_u64_rem +extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder); +#endif + #ifndef div64_u64 extern u64 div64_u64(u64 dividend, u64 divisor); #endif diff --git a/lib/div64.c b/lib/div64.c index a163b6caef73..4382ad77777e 100644 --- a/lib/div64.c +++ b/lib/div64.c @@ -79,6 +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 |