[v5,1/6] math64: New DIV_U64_ROUND_CLOSEST helper

Commit Message

Pali Rohár Aug. 9, 2021, 2:53 p.m. UTC

Provide DIV_U64_ROUND_CLOSEST helper which uses div_u64 to perform
division rounded to the closest integer using unsigned 64bit
dividend and unsigned 32bit divisor.

Signed-off-by: Pali Rohár <[e-mail]>
---
 include/linux/math64.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Patch

diff --git a/include/linux/math64.h b/include/linux/math64.h
index 66deb1fdc2ef..1cc61d748e1f 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -281,6 +281,19 @@  u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div);
 #define DIV64_U64_ROUND_CLOSEST(dividend, divisor)	\
 	({ u64 _tmp = (divisor); div64_u64((dividend) + _tmp / 2, _tmp); })
 
+/*
+ * DIV_U64_ROUND_CLOSEST - unsigned 64bit divide with 32bit divisor rounded to nearest integer
+ * @dividend: unsigned 64bit dividend
+ * @divisor: unsigned 32bit divisor
+ *
+ * Divide unsigned 64bit dividend by unsigned 32bit divisor
+ * and round to closest integer.
+ *
+ * Return: dividend / divisor rounded to nearest integer
+ */
+#define DIV_U64_ROUND_CLOSEST(dividend, divisor)	\
+	({ u32 _tmp = (divisor); div_u64((u64)(dividend) + _tmp / 2, _tmp); })
+
 /*
  * DIV_S64_ROUND_CLOSEST - signed 64bit divide with 32bit divisor rounded to nearest integer
  * @dividend: signed 64bit dividend