Merge remote-tracking branch 'libata/for-next'

[karo-tx-linux.git] / lib / div64.c

diff --git a/lib/div64.c b/lib/div64.c
index a163b6caef73fdc26e19f8d18ef66604a03b1cf8..4382ad77777ebcb17bc4b25fe606f4371b563a5d 100644 (file)
--- a/lib/div64.c
+++ b/lib/div64.c
@@ -78,6 +78,46 @@ s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
 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