commit f792685006274a850e6cc0ea9ade275ccdfc90bc upstream.
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@xxxxxxxxx>
Cc: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
---
include/linux/math64.h | 19 ++++++++++++++++++-
lib/div64.c | 19 +++++++++++++------
2 files changed, 31 insertions(+), 7 deletions(-)
diff --git a/include/linux/math64.h b/include/linux/math64.h
index b8ba855..931a619 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -30,6 +30,15 @@ static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
}
/**
+ * div64_u64_rem - unsigned 64bit divide with 64bit divisor
+ */
+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)
@@ -61,8 +70,16 @@ 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);
+static inline u64 div64_u64(u64 dividend, u64 divisor)
+{
+ u64 remainder;
+ return div64_u64_rem(dividend, divisor, &remainder);
+}
#endif
#ifndef div64_s64
diff --git a/lib/div64.c b/lib/div64.c
index a163b6c..3af5728 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
/**
--
1.7.11.7
--
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