X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;ds=sidebyside;f=lib%2Fdiv64.c;h=4382ad77777ebcb17bc4b25fe606f4371b563a5d;hb=78d4a42069b4815040a857a4e9bb0e4fb0aa1dc8;hp=3af5728d95fda3c2aa740deec3f6de69cc847e94;hpb=3ed1c478eff8db80e234d5446cb378b503135888;p=~andy%2Flinux

diff --git a/lib/div64.c b/lib/div64.c
index 3af5728d95f..4382ad77777 100644
--- a/lib/div64.c
+++ b/lib/div64.c
@@ -79,16 +79,15 @@ EXPORT_SYMBOL(div_s64_rem);
 #endif
 
 /**
- * div64_u64_rem - unsigned 64bit divide with 64bit divisor and 64bit remainder
+ * div64_u64_rem - unsigned 64bit divide with 64bit divisor and 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
- * can be found here and is available for use without restriction.
- *
- * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt'
+ * 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)
@@ -119,6 +118,40 @@ u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
 EXPORT_SYMBOL(div64_u64_rem);
 #endif
 
+/**
+ * div64_u64 - unsigned 64bit divide with 64bit divisor
+ * @dividend:	64bit dividend
+ * @divisor:	64bit divisor
+ *
+ * This implementation is a modified version of the algorithm proposed
+ * by the book 'Hacker's Delight'.  The original source and full proof
+ * can be found here and is available for use without restriction.
+ *
+ * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt'
+ */
+#ifndef div64_u64
+u64 div64_u64(u64 dividend, u64 divisor)
+{
+	u32 high = divisor >> 32;
+	u64 quot;
+
+	if (high == 0) {
+		quot = div_u64(dividend, divisor);
+	} else {
+		int n = 1 + fls(high);
+		quot = div_u64(dividend >> n, divisor >> n);
+
+		if (quot != 0)
+			quot--;
+		if ((dividend - quot * divisor) >= divisor)
+			quot++;
+	}
+
+	return quot;
+}
+EXPORT_SYMBOL(div64_u64);
+#endif
+
 /**
  * div64_s64 - signed 64bit divide with 64bit divisor
  * @dividend:	64bit dividend