diff options
| author | Frederic Weisbecker <fweisbec@gmail.com> | 2013-03-05 18:05:46 +0100 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2013-03-13 18:03:27 +0100 |
| commit | f792685006274a850e6cc0ea9ade275ccdfc90bc (patch) | |
| tree | 712b47504d4e62906e966abef11c2e051a028889 /lib | |
| parent | 660cc00f8c6f7a2e16c25918590b470e86de19ec (diff) | |
math64: New div64_u64_rem helper
Provide an extended version of div64_u64() that
also returns the remainder of the division.
We are going to need this to refine the cputime
scaling code.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/div64.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/lib/div64.c b/lib/div64.c index a163b6caef7..3af5728d95f 100644 --- a/lib/div64.c +++ b/lib/div64.c @@ -79,9 +79,10 @@ EXPORT_SYMBOL(div_s64_rem); #endif /** - * div64_u64 - unsigned 64bit divide with 64bit divisor + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and 64bit remainder * @dividend: 64bit dividend * @divisor: 64bit divisor + * @remainder: 64bit remainder * * This implementation is a modified version of the algorithm proposed * by the book 'Hacker's Delight'. The original source and full proof @@ -89,27 +90,33 @@ EXPORT_SYMBOL(div_s64_rem); * * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt' */ -#ifndef div64_u64 -u64 div64_u64(u64 dividend, u64 divisor) +#ifndef div64_u64_rem +u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) { u32 high = divisor >> 32; u64 quot; if (high == 0) { - quot = div_u64(dividend, divisor); + 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--; - if ((dividend - quot * divisor) >= divisor) + + *remainder = dividend - quot * divisor; + if (*remainder >= divisor) { quot++; + *remainder -= divisor; + } } return quot; } -EXPORT_SYMBOL(div64_u64); +EXPORT_SYMBOL(div64_u64_rem); #endif /** |