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authorFrederic Weisbecker <fweisbec@gmail.com>2013-03-05 18:05:46 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2013-03-13 18:03:27 +0100
commitf792685006274a850e6cc0ea9ade275ccdfc90bc (patch)
tree712b47504d4e62906e966abef11c2e051a028889 /lib/div64.c
parent660cc00f8c6f7a2e16c25918590b470e86de19ec (diff)
downloadleg-kernel-f792685006274a850e6cc0ea9ade275ccdfc90bc.tar.gz
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/div64.c')
-rw-r--r--lib/div64.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/lib/div64.c b/lib/div64.c
index a163b6caef73..3af5728d95fd 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
/**